Assisted Migration (Assisted Colonization, Managed Relocation, Translocation) and Rewilding of Plants and Animals in an Era of Rapid Climate Change

EDITOR'S NOTE: This annotated and linked list of online-accessible papers, articles, and news reports on assisted migration (aka: assisted colonization / colonisation, translocation, managed relocation, facilitated migration, and "neo-natives") aims to further professional and popular understanding of both the substance and history of debate and actions regarding one of the most significant developments in conservation biology. This list is continually updated; entries are ordered only loosely by date, with more attention given to academic importance, insight into shifting conservation values, expansive treatment of the debate, and provision of background understanding.

  • ASSISTED MIGRATION in FORESTRY: Most academic papers that have been cautious or critical of assisted migration as a management tool for coping with climate change have been written within the paradigm and professions of conservation biology and restoration ecology. As you scroll down this list, most of the online entries are of that group. But forestry professionals have been ahead of other scientific disciplines in accepting assisted migration as a necessary tool to keep forests healthy in a rapidly changing climate — and they have been engaging in this practice for a rather long time (often calling it facilitated migration). Click to jump to the special section on "Assisted Migration for Forests of North America".

  • "Assisted migration" articles/papers (which primarily deal with helping extant species move as climate changes) are listed immediately below. Click to skip down to where "Pleistocene Rewilding and Taxon Substitution for Ecological Restoration" begins.

    IPCC 2014 Report

    Climate Change 2014

    Impacts, Adaptation, and Vulnerability"

       In the 44-page "SUMMARY FOR POLICYMAKERS" of this multi-volume report, Figure SPM.5, along with its caption and a summary paragraph, refer not only to the possible need for "assisted species migration", which ongoing climate change could necessitate to avert extinction and ecological disruptions, but also points to trees as being the most vulnerable of all life forms — and thus the most in need of human assistance to keep pace with climate zone changes. Trees are represented in the left-most vertical bar in image left, "Maximum speed at which species can move (km per decade)".

    (p. 15) "Many species will be unable to track suitable climates under mid- and high-range rates of climate change during the 21st century (medium confidence). Lower rates of change will pose fewer problems. Some species will adapt to new climates. Those that cannot adapt sufficiently fast will decrease in abundance or go extinct in part or all of their ranges. Management actions, such as maintenance of genetic diversity, assisted species migration and dispersal, manipulation of disturbance regimes (e.g., fires, floods), and reduction of other stressors, can reduce, but not eliminate, risks of impacts to terrestrial and freshwater ecosystems due to climate change, as well as increase the inherent capacity of ecosystems and their species to adapt to a changing climate (high confidence)."

    Note: Connie Barlow made the above IPCC diagram the central figure for her April 2014 presentation in Prescott AZ on climate change and assisted migration: "Forest Trees in Climate Peril" (Connie Barlow 2014). Her discussion of the diagram begins at 10:40.

    The "IUCN Guidelines for Reintroductions and Other Conservation Translocations" 2012 update makes a distinction between two forms of "translocations" that would be characterize conservation actions responsive to the ecological upsets of climate change:

  • ASSISTED COLONIZATION is the intentional movement and release of an organism outside its indigenous range to avoid extinction of populations of the focal species.

  • ECOLOGICAL REPLACEMENT is the intentional movement and release of an organism outside its indigenous range to perform a specific ecological function.

    See the 3-fold chart immediately below for distinctions between three forms of climate-responsive assisted colonization, as set forth by foresters.

  •     "Assisted Migration: What It Means to Nursery Managers and Tree Planters", intended for landscapers and their clients, urges that planting for climate change become integral to the profession. Three types of climate assistance are:

    (1) Assisted population migration
    (2) Assisted range expansion
    (3) Assisted species migration

    Note: Species examples for each: Western Larch, Ponderosa Pine, Florida Torreya

        The SUNY College of Environmental Science and Forestry launched in April 2014 Move It?, an online questionnaire that scores the suitability of user-defined species (candidate taxa) for assisted colonization. Questions are divided into three main categories, following Hoegh-Guldberg et al. (2008): (1) need for assisted colonization, (2) technical feasibility of assisted colonization, and (3) biological/ socioeconomical costs versus benefits of assisted colonization.

    Move It? is also a growing database of user-submitted scores, which can then be used to compare candidate taxa and guide decisions about the use of assisted colonization in practice. Although primarily developed in the context of climate change, Move It? can be used to evaluate any proposal to translocate organisms outside their current range. Take the Survey!

        A September 2014 4-page article, "Have Tree, Will Travel" is a superb way to grasp the paleoecological foundation that undergirds projects for which poleward "assisted migration" on the continent of origin is becoming standard practice in this century of rapid climate change. The author, park planner Kevan Williams, weaves the science and policy viewpoints into three sequential narratives:
        (1) a futile recent Nature Conservancy project of attempting to "rewild" a native camellia, Franklinia alatamaha, southward to its "native" (actually, peak-glacial) habitat in southern Georgia from its cultivated (rescue) domain near Philadelphia.
        (2) the ongoing (and thus far successful) attempt by citizen naturalists to work around the Endangered Species Act and thus on their own initiative move a critically endangered Florida conifer, Torreya taxifolia (photo left), from its peak glacial refuge in northern Florida into the southern Appalachians and points farther north.
        (3) the disaster looming large for even common forest trees, as climate shifts rapidly, along with the role that massive projects of assisted migration, on the one hand, and urban forest landscaping, on the other, could play in helping species move north.
    "Climate change to Philly trees: It's not 1910 anymore" (news article) by Carolyn Beeler, 23 January 2015. Surveys Philadelphia and Chicago urban trees and parks managers who have already begun planting more southerly tree species on municipal lands. Joan Blaustein, head of urban forestry and ecosystem management at the Philadelphia Parks Department, is quoted: "We need to anticipate what the conditions are going to be 100 years from now, rather than trying to restore to 100 years ago." Beeler writes, "In the fall, the city will plant non-native trees suited to warmer climates, including the Southern chestnut oak and bald cypress, and plant some species native to Pennsylvania that are currently at the northern end of their range, such as the Southern red oak and red mulberry. . . In five years, Blaustein hopes the early results of her experimental test plots will give her an idea of which new trees to plant city-wide."

        January 2014, Connie Barlow (founder of Torreya Guardians) launched on youtube an EDUCATIONAL VIDEO SERIES on Assisted Migration that extends the learnings and experience within Torreya Guardians to potentially apply to private landowners throughout the USA who want to begin experimenting on their own lands with helping even common tree species (especially large-seeded species dependent on rodents for range extension) to move northward in anticipation of climate change — climate change that may push habitable ranges northward faster than the trees can "move" on their own. This newly suggested activity for citizen naturalists: Leaf a Legacy.

    Access: "Climate, Trees, and Legacy VIDEOSERIES".
    Episodes: 01 - Introduction; 02 - Lessons of Torrey Pine; 03 - Lessons of Joshua Tree; 04 - Lessons of Arizona Cypress; 05 - Rocky Mountain Trees in Climate Peril; 06 - Becoming Passenger Pigeon

  • "Species Migration Shaping Ecosystems of the Future" by Ruby Russell, 14 October 2014, Deutsche Welle
    KEY POINT: Those of us in the northern hemisphere may need to assist the poleward migration of today's even common species, but the biggest problem resides in the Southern Hemisphere — where terrestrial species may ultimately run out of southern latitude lands, owing to the shape and locations of the continents.

    CONCLUDING EXCERPT: "Looking at all life-forms, it is trees that move the slowest. The majority of trees cannot keep pace with climate change," Torreya Guardians' founder Connie Barlow says, adding that the Florida torreya's seeds are too large to be carried by the wind or most animals. Assisted migration is controversial, but Barlow and others argue that on a continental landmass like Europe or North America, terrestrial species have shifted back and forth with climatic change over the millennia, so that what seem like 'new' species combinations have actually existed in the past.
         What is unprecedented is the rate at which climate change is now happening. Chris Thomas says this means defending current species combinations may not always be the best approach. "If all our biological communities are going to change anyway, why should we not think about including within those biological communities — even if it requires us to intervene — some of those species which are truly endangered?" asks Thomas. He says some may not think this is very natural. But, then neither is current climate change, he points out.

  • "University of Arizona Study: Evolution Too Slow to Keep Up with Climate Change" press release of "Rates of projected climate change dramatically exceed past rates of climatic niche evolution among vertebrate species" by Ignacio Quintero and John J. Wiens, Ecological Letters August 2013 (abstract)
    EXCERPT (from press release): "Many vertebrate species would have to evolve about 10,000 times faster than they have in the past to adapt to the rapid climate change expected in the next 100 years, a study led by a University of Arizona ecologist has found. . .  terrestrial vertebrate species appear to evolve too slowly to be able to adapt to the dramatically warmer climate expected by 2100. The researchers suggested that many species may face extinction if they are unable to move or acclimate. . . The sampling covered 17 families representing the major living groups of terrestrial vertebrates, including frogs, salamanders, lizards, snakes, crocodilians, birds and mammals.

  • Botanic Gardens to participate in Assisted Migration:
    1. Botanic Gardens Conservation International (BGCI) climate change and assisted migration programs. Webpages include: "The assisted migration debate: botanic gardens to the rescue?" and "Chaperoned Managed Relocation. Access a white paper on chaperoned assisted migration written by the Missouri Botanical Garden in October 2013. EXCERPT: "In contrast to managed relocation where species would be transferred from one natural area to another, we propose a program of 'chaperoned' managed relocation in which species would be transferred from natural areas to botanical gardens. As climate continues to change, populations would be transferred serially from garden to garden. Chaperoned managed relocation should only occur within each species' 'potential dispersal envelope,' meaning the area into which the species could be expected to naturally migrate, were climate change slower and habitats less fragmented by roads, fields, and cities."
        Highly recommended: Box 1 of the Missouri Botanical Garden paper directly addresses the need to "bridge the two cultures" of botanical gardens and conservation biology.

    2. "Plan Seeks 'Chaperones' for Threatened Species" news report on a talk by Adam Smith (ecologist at Missouri Botanical Garden) presented at the Ecological Society of America meeting, August 2013. Report by Virginia Gewin, published in Nature 09 August 2013
         EXCERPT: "Critics claim that such 'assisted migration' could transform struggling species into destructive invaders, or inadvertently transmit disease, or that hybridization between species could occur that would lower the planet's overall genetic diversity. But without some form of assistance, many plants will face certain extinction as the planet warms. With that in mind, researchers are proposing a heavily supervised form of assisted migration — using a network of more than 3,100 botanical gardens to 'chaperone' plant relocations. . . The researchers recommend that endangered species collected in the wild should be relocated to botanical gardens in stages, moving between gardens following a dispersal path that would be considered an evolutionarily realistic response to climate change. . .  With few other options for preserving rare and threatened species in the face of global warming, [Adam] Smith and his colleagues are forging ahead with their plans. They aim to release a more detailed proposal in October at the 5th Global Botanic Gardens Congress in Dunedin, New Zealand, that is likely to include a list of candidate species. They also hope to start a pilot project soon to test the feasibility and cost of chaperoning. See also the detailed blog on this topic by Kate Whittington, "Plant Pioneers: Assisting The Migration Of Climate-Endangered Species".

        Secrest Arboretum in Wooster Ohio participates in Florida Torreya assisted migration. Fred Bess of Cleveland Ohio (left in photo) is the Torreya Guardians liaison collaborating with Ohio State University's Secrest Arboretum (Paul Snyder is at right in photo) to encourage and foster the planting of a Torreya taxifolia grove on their grounds. A 10-minute video, recorded by Connie Barlow during a site visit in September 2014, shows the early stages in that effort.

    Note: The photo at left shows the potted seedlings (grown from seeds harvested autumn 2011 by Torreya Guardians) that will eventually be planted out on the arboretum grounds.

  • Assisted Migration Debate Takes a Sharp Turn in May 2013 - On May 8, CO2 in the atmosphere reached 400 ppm for the first time in human history. On May 9, Science journal published a stunning analysis of Siberian lake-sediment data that offers irrefutable evidence that a 400 ppm atmosphere (when it equilibrates air and ocean conditions) will produce an ice-free Arctic. Henceforth, responsible discourse about assisted migration will no longer question should it be undertaken, but rather when, how, and by whom. Below are the key links to the May 9 paper, beginning with the paper's title and abstract page.
  • "Pliocene Warmth, Polar Amplification, and Stepped Pleistocene Cooling Recorded in NE Arctic Russia" by Julie Brigham-Grette and 15 international coauthors, in Science May 9, 2013.

  • "The Arctic was once warmer, covered by trees": Pliocene epoch featured greenhouse gas levels similar to today's but with higher average temperatures", reported by Erin Wayman in Science News, 9 May 2013.

  • "Climate Sensitivity Stunner: Last Time CO2 Levels Hit 400 Parts Per Million The Arctic Was 14¡F Warmer!", blogpost by Joe Romm, 12 May 2013

  • IUCN updated in 2013 its "Guidelines for Reintroductions and Other Conservation Translocations" because, "while 'assisted colonisation' is controversial, it is expected to be increasingly used in future biodiversity conservation."
  • "Managed Relocation: Integrating the Scientific, Regulatory, and Ethical Challenges" by Mark W. Schwartz and 30 coauthors, BioScience August 2012 (12 pp in pdf)
    EXCERPT: "We report on the findings of the Managed Relocation Working Group (MRWG), an independent collection composed of over 30 scientists, scholars, and policymakers that met to discuss dimensions of managed relocation. Managed relocation raises a difficult suite of biological, legal, and ethical issues. Owing to the nature of this committee, most of the examples refer specifically to the United States, but the issues we treat are broadly applicable, including those related to policy. The MRWG represents an interdisciplinary group seeking a comprehensive consideration of managed relocation.
        "Conservation ecologists are beginning to call for adapting management strategies for climate change (e.g., increasing the connectivity, resistance, and resilience of natural protected areas; e.g., Heller and Zavaleta 2009). Others have suggested more radical approaches, such as embracing novel anthropogenic ecosystems as a management goal (Hobbs et al. 2006, Thomas 2011). The proponents of managed relocation contend that conventional conservation strategies will not provide sufficient protection from future environmental change (Vitt et al. 2010, Thomas 2011).
        "Our view is that the starting point for developing a decision framework for managed relocation should be an examination of the goals of conservation, values underlying those goals, and the possibility for conflict among both goals and underlying values. The next step is to examine the legal and institutional framework within which managed relocation decisions are made. Third, we must develop and agree on scientific standards of evidence to support managed relocation decisions. Finally, we must create tools for resolving goal or value conflicts. Toward this end, the MRWG identified a series of ethical, policy, ecological, and integrated questions that should be answered to support a socially and scientifically acceptable decision framework.
        "There are thorny ethical questions surrounding any shift to an adaptationist understanding of conservation ethics and policy that would sanction managed relocation. The conservation message for decades has stressed the importance of saving species within historical ranges. Managed relocation may create perverse opportunities for relaxing societal commitments to habitat protection (Camacho 2010). Perhaps an even more troubling question is whether the acceptance of adaptive and anticipatory strategies, such as managed relocation, will function as a moral hazard by undercutting society's resolve to pursue aggressive climate change mitigation policies. There is a danger that even a measured adoption of managed relocation will encourage ethically irresponsible behavior. Policies sanctioning managed relocation could therefore provide leverage to those who wish to dismantle legal and policy tools designed to protect species and their habitats. Policymakers will have to take great care in communicating the need for relocation proposals to a public with divided interests so that policy revisions do not confuse and weaken human ethical responsibilities toward conservation."
        Editor's note: This paper is an ideal place to learn about the full history of and key publications on this issue, as of mid 2012. The table below is reprinted from this paper.

  • COMMENTS (on the above 31-coauthor paper), along with RECOMMENDATIONS for further policy work, were posted by Connie Barlow, Torreya Guardian, December 2012.

  • A now-classic paper establishing "intervention ecology" in opposition to rigid adherence to historical baselines (applied within "restoration ecology") is important reading in this assisted migration debate. See "Intervention Ecology: Applying Ecological Science in the Twenty-first Century", 2011 BioScience, Richard J. Hobbs et al. (Paul Ehrlich is among the coauthors).

  • Lead author Mark W. Schwartz continues to advocate structured decision-making prior to "managed relocation" in a 2013 article, in which climate change as an impetus for such species relocations is added to the mix: "Translocation of Imperiled Species Under Changing Climates", Annals of the New York Academy of Sciences.

  • "An Assessment of Invasion Risk from Assisted Migration" by Jillian M. Mueller and Jessica J. Hellmann, Conservation Biology, 28 June 2007.
    Content: Distinguishes history of inter- v. intra-continental invasive species in assessing the risks. Concludes that fish and crustaceans may pose a high risk. "We conclude that the risk of AM to create novel invasive species is small, but assisted species that do become invasive could have large effects."

    Editor's note: In 2014, a team of authors proposed "A Unified Classification of Alien Species Based on the Magnitude of their Environmental Impacts", which is essential for distinguishing the vast gray zone of problems caused by non-natives (those worth fighting against v. those worth simply accepting as part of the new landscape).

  • "Translocation of Species, Climate Change, and the End of Trying to Recreate Past Ecological Communities" by Chris D. Thomas, Trends in Ecology and Evolution, May 2011.
    Abstract: Many of the species at greatest risk of extinction from anthropogenic climate change are narrow endemics that face insurmountable dispersal barriers. In this review, I argue that the only viable option to maintain populations of these species in the wild is to translocate them to other locations where the climate is suitable. Risks of extinction to native species in destination areas are small, provided that translocations take place within the same broad geographic region and that the destinations lack local endemics. Biological communities in these areas are in the process of receiving many hundreds of other immigrant species as a result of climate change; ensuring that some of the 'new' inhabitants are climate-endangered species could reduce the net rate of extinction.

    EDITOR'S NOTE: For suggested standards for translocations of aquatic species, see "Challenges and Opportunities in Implementing Managed Relocation for Conservation of Freshwater Species" by Julian D. Olden et al., Conservation Biology, February 2011. See also "Standards for Assisted Migration, which was posted on the Torreya Guardians website in 2004.

  • "The precautionary principle in managed relocation is misguided advice" by Mark W. Schwartz, Jessica J. Hellmann, and Jason S. McLachlan, Trends in Ecology and Evolution 2009
    EXCERPT: "The precautionary principle has been historically useful in guiding conservation management, but global environmental change presents a different sort of problem. There are real risks of harm to biodiversity through inaction as well as action. The only way forward to confront unprecedented problems such as global anthropogenic climate change is careful risk analysis, including an honest evaluation of uncertainty and potential harm, along with broad public debate beyond the technical expertise of scientists and managers. We must engage in careful study of ethical, legal and biological issues surrounding the idea of managed relocation even if the ultimate conclusion is that it is the wrong approach to managing a difficult problem."
    NOTE: The September 2009 issue of Trends in Ecology and Evolution contains a total of 6 short papers or opinion pieces on the issue of assisted migration.

  • "Commercial trade of federally listed threatened and endangered plants in the United States" (abstract) by Patrick D. Shirey et al., Conservation Letters Sept/Oct 2013, pp. 300-316.
    Note: This paper clearly establishes the legality of non-commercial translocations ("assisted migration", "assisted colonization") of endangered plant species in the USA. The voluntary efforts of citizen-naturalists in Torreya Guardians (assisting the northward movement of Torreya taxifolia) are used as a key example of such legal practices.

    EXCERPTS: "a listed plant could be purchased in one state and then transported to another state without violating the ESA, so long as the plant was taken from and planted on property not under Federal jurisdiction, such as private property. Furthermore, the ESA does not prohibit an individual from giving listed plants as a gift to someone in another state so long as a change in plant ownership is not in the pursuit of gain or profit." . . . In the United States, the structure of the Endangered Species Act, coupled with inadequate funding for endangered plant conservation, has encouraged citizens to undertake plant conservation, especially for charismatic plants threatened by climate change. For example, the Torreya Guardians have obtained plants and seeds of Florida torreya (Torreya taxifolia), and moved seedlings and saplings to the southern Appalachian Mountains, outside of the species' historic range (McLachlan et al. 2007; . . In contrast to accepted ex situ conservation practices (Haskins & Keel 2012), the Torreya Guardians established private experimental populations on the property of cooperative landowners to help preserve the species outside of its historic range because of its decline, lack of federal funding, and the availability of privately owned and commercially available plants and seeds. . . Finally, under U.S. federal law, citizens who move a listed plant are not constrained by the same assessment process as the federal government — their actions are legal under the ESA without a review of their plans. MORE EXCERPTS available in PDF. See also "Scientific American blog" on this topic (July 2013).

    Note: Because the Shirey et al. paper established the legality of Torreya Guardian actions "rewilding" an endangered conifer tree (Torreya taxifolia) far north of its climate-stressed "critical habitat," activist Connie Barlow recorded in November 2013 a 75-minute VIDEO BLOG (right), posted on Youtube, to summarize the group's learnings to date.

    Note: To go directly in the video to the importance of the Shirey et al. paper, click here, or click on the "Show more" link below the Youtube caption and see the full table of contents of the video, hotlinked by time codes.


  • "The Nature Conservancy: Adaptation Forestry in Minnesota's Northwoods" July 2013 status report by The Nature Conservancy.
    EXCERPTS: "In June 2013, over 33,000 seedlings from a combination of species and seed zones were planted at several project sites in northeastern Minnesota. Further planting will occur in 2014.

    "The Nature Conservancy is coordinating this project, in collaboration with the Northern Institute of Applied Climate Science (NIACS), University of Minnesota-Duluth, and other organizations. The project is being implemented on approximately 2,000 acres of forestland in northeastern Minnesota, on a mix of federal, state, and county land.

    "Much of current forest management in northeastern Minnesota focuses on maintaing and restoring native boreal species, such as aspen and white spruce. At the same time, forest composition in northeastern Minnesota is projected to change as the climate changes, and recent research suggests that these same species are at greater risk in a changed climate. These anticipated changes suggest that, in the long term, climate change may be working in direct opposition to some current restoration management actions.

    Modeling studies project changes in forest composition in northeastern Minnesota under future climate scenarios, including a shift towards more maple and a less diverse forest composition across the northern forested landscape. This suggests that many of the tree species that are currently a focus of restoration efforts, with the exception of white pine, may be unsuited to future conditions compared to more southerly distributed species, such as maples and oaks. More details are available in the TNC Background Study Summary."

    Note: See a superb, long popular article on this assisted migration action in a 2013 issue of the Minneapolis Star Tribune: "Saving the Great North Woods". Excerpt: "Driven by a warming climate, scientists predict, the [boreal forest in NE Minnesota] will soon follow the glaciers and retreat north by as much as 300 miles in the next century. Much of northern Minnesota, they say, will become open savannas like those in Nebraska and eastern Kansas — with grasses and brush, a few scattered trees, and domes of bare rock rising from the ground." Note: The article contains 2 excellent VIDEOS to watch. See also a 3 September 2014 news report on this project: "Moving a Forest: as climate changes, ecosystems will need to shift". Below is an excerpt from an October 2014 article in The Guardian, "If You Plant Different Trees in the Forest, Is It Still the Same Forest?".

    The Nature Conservancy will plant seeds for 100,000 red oak, bur oak and white pine trees on 2,000 acres of federal, state and local forests in Minnesota's Iron Range. Seeds from each species will come from two zones: one from within the test range, and another from distant parts of the species' historic range (mostly from southern Minnesota, and, in some cases, a portion of Michigan where the trees exist). Researchers from the University of Minnesota Duluth will then manage these test forests in different ways to find out whether varying how the trees are planted and managed affect how each species fares; how different climate conditions affect their viability; and whether seeds originating from other parts of the forest — where different conditions exist — impact how two seemingly identical trees withstand the same conditions. . . The term "assisted migration" was coined after proposals to transplant Torreya [trees] from Florida to North Carolina in 2007 sparked heated debate. But Julie Etterson, the University of Minnesota biologist conducting the study with the Nature Conservancy, says the definition of the practice isn't completely clear. Critics often seem to judge assisted migration projects using a double standard: traditional forestry practices are far more disruptive than the movement of small samples of distant genotypes that are part of the same species, she claims. While some ecologists believe that humans have meddled enough with the wilderness, others take a more pragmatic perspective. Meredith Cornett (of the Nature Conservancy) argues that there is an urgent need to do something to help Minnesota's forests survive. "We could argue that we should just let nature take its course, but nature has never really faced this situation before," she says. "We've just never seen things changing at this pace."

  • "Endangered Species: Will it be extinction or translocation as impacts of climate change increase?" by Niina Heikkinen, Climate Wire 15 August 2014
    SUMMARY: Short investigative article on shifting views in whether 'translocation' (assisted migration) of endangered species should be normalized as non-controversial, given the inexorable trends in climate change. Lee Barnes of Torreya Guardians was interviewed for this piece. Key statements by Chris Thomas, professor of biology at University of York (U.K.): "Many of the threatened species are just the kind of spices that can't move on their own." In Thomas's opinion, criticism of translocation is "driven by nostalgia, or a feeling that there was a romanticized period in the past when somehow humanity and nature were in balance." As to the potential danger that a translocated species might become invasive in the recipient ecosystem, Thomas counters that endangered species should be regarded as "innocent until proven guilty."

  • "Species Conservation, Rapid Environmental Change, and Ecological Ethics" by Ben A. Minteer, The Nature Education Knowledge Project 2012
    EXCERPT: "Rapid, large-scale environmental changes are forcing conservationists to consider innovative and often controversial tactics for protecting species in this century, tactics that raise significant ethical and value-laden questions. Given what we already know about changes in species' ranges and abundances in the face of global climate change, it is inevitable that conservation in the post-preservationist era will require more interventionist conservation policies, leading to debates regarding risks, benefits, and likely success of novel practices such as managed relocation."

    See also Minteer's "Restoring the Narrative of American Environmentalism", January 2013, Restoration Ecology.

    VIDEO ABOVE LEFT: Alejandro Camacho 2011: Redefining Nature through Assisted Migration (Natural Resources Law and Ethics Under Climate Change; 21 minutes)

    29:19 Begins • 31:21 Torreya example • 32:42 "Why do it, and why is this controversial? The existing literature focuses on whether assisted migration can be done — what I call, questions of scientific viability or legality. But I argue that the concerns with it, at their root, are deeply normative. They're really ethical. Assisted migration challenges deeply entrenched ideas about what the purposes are of natural resource law and natural resources management. But I argue that it is these principles and the legal framework that require rethinking." • 40:11 "We need to reinvent resource management to better reflect a dynamic world … "Natural resources management was not designed with climate change in mind." • 47:35 "I argue that climate change necessitates managing for the future." • 51:19 "I think assisted migration illustrates how resource management is not exclusively a scientific or legal inquiry."

    VIDEO ABOVE RIGHT: Alejandro Camacho 2012: Why Federal Climate Change Legislation Shouldn't Stop States from Innovating in Adaptation Efforts (29 minutes)

    00:01 Begins • 01:24 "My claim is that the law in the United States is not well suited to cultivate successful adaptation because it's not designed to foster learning." • 02:12 "U.S. law is not well suited to foster adaptation because it relies on (in fact, promotes) a very static view of nature and natural systems." • 04:45 "Climate change adaptation in particular is problematic because determining what are suitable adaptations is largely affected by the extent of mitigation … And we don't know that … So knowing what adaptation strategies to adopt, to restore certain mangroves, when we don't actually know if 50 to 100 years from now, whether all that work is wasted, is really problematic." • 06:21 "Scientists are really being challenged to reconsider long-held assumptions and long-held methodologies they've relied on. Regulators and managers are being asked to prepare for problems that they haven't ever faced before." • 06:54 "The most important strategies for effective adaptation, therefore, are those that help reduce uncertainty and that promote learning by managers and stakeholders in particular. [He cites 2 problems in the US] (1) Agencies are really slow to adapt to new information or changed circumstances. They aren't required to adjust their strategies over time … They don't gather information as to the effectiveness of their strategies; so the consequences are weak accountability. (2) Natural resources management in the U.S. is very fragmented, with at best weak coordination. It's not designed with climate change in mind. … It also hinders the capacity for learning between agencies." • 11:18 "Natural resources law in the United States is badly fitted for addressing the effects of climate change because of its goal, because of its objectives … grounded in a preservationist or restorationist baseline, a historical baseline . . . shielding nature from active human intervention … minimizing non-native and protecting native … Climate change reveals the limits of both of these versions of preservationism." • 15:23 "There is little ethical foundation for arresting the evolution of pre-existing ecosystems … Some of the reserves that have been set aside may actually become inhospitable to the very resources that they were created to protect." • 16:08 "Finally, climate change really pits these two different types of preservation — wildness preservation and historical preservation — against each other. Climate change makes it impossible to do both. You can't keep things the way they are and also leave them alone." • 22:02 "By not requiring agencies to monitor, to revisit, to adjust their decisions, to learn, this makes agencies less accountable to the public." • 25:15 "What climate change makes clear is that ecology and natural resource management should not be left solely to an expert: an economist, an ecologist. These are democratic decisions." • 29:00 Q&A starts

    See also print versions of these papers:

    2011: Alejandro Camacho's 2011, "A Learning Collaboratory: Improving Federal Climate Change Adaptation Planning"

    2010: "Why Federal Climate Change Legislation Shouldn't Stop States From Innovating in Adaptation Efforts"

    Note: Serious students of assisted migration or, more broadly, the need for profound professional and public reconsideration of ecological norms in a time of rapid climate change will find it important to read the 86-page (freely downloadable) paper by Camacho, quotations from which follow:

  • "Assisted Migration: Redefining Nature and Natural Resource Law Under Climate Change", by Alejandro E. Camacho, 2010, in Yale Journal on Regulation, vol 27, pp 171-255.
    [86-pages in PDF freely downloadable] Argues for the necessity of assisted migration, owing to ongoing and projected climate change, and suggests changes in the U.S. ESA and regulatory policies for making this possible. Boldly addresses ethical concerns and the need for public discussion in the context of how assisted migration is a leading-edge issue that reveals the scope to which ecological preservation, restoration, and management will need to be thoroughly in light of the new awareness of significant climate change. Key quotations:

    Page 189: "Paradoxically, as detailed in the following subsections, under existing law it may often be more difficult for federal agencies to engage in assisted migration than it is for private parties."

    Page 243: "Assisted migration illustrates how climate change compels a reassessment of three key features of modern American natural resource governance. First, assisted migration demonstrates how climate change inevitably compels a reassessment away from baseline goals that seek to preserve or restore historical or existing conditions to a focus on maximizing desirable future conditions, although the particular formulation of such a goal for natural resource management is very much unresolved. Second, while making clear that biotic interactions will change considerably with or without direct human involvement, climate change necessarily reshapes the primary unit to target for management away from individual species or even assemblages of species toward ecological processes. Yet again, concretely steering resource management toward such a focus remains elusive. Third, the swiftness of climate change demonstrates that distinctions previously made in natural resource policy between native and exotic, or between natural and introduced, are overly simplistic and anchored in the flawed notion that the world is inert. Public resource management must explore new management standards for determining what ecological conditions are desirable or acceptable. Each of these necessitates substantial further public discussions to ascertain the future of public natural resource policy — and thus the prospects for assisted migration."

    page 244: "The conflict over assisted migration shows that the goal of preserving or restoring resources to a historic baseline that currently dominates natural resource policy will be increasingly difficult if not impossible to sustain. More than ever, modern anthropogenic climate change emphasizes the necessity of actively managing for the future. Yet the particular shape of such an objective is far from clear. As such, climate change necessitates extensive public discussions and ultimately legislative guidance regarding what is valuable and important to the public about natural resources such as endangered species and existing biotic communities."

    page 245: "Similarly, natural resource management must be transformed away from a primary focus on preserving or restoring historical biotic assemblages. With significant alterations in climatic conditions anticipated for many ecosystems, preservation and restoration goals will be increasingly unsustainable. Accordingly, statutes like the National Park Service Organic Act and Wilderness Act that primarily seek to preserve historical conditions will need to be reconceived away from a strict fidelity to the past toward a greater focus on promoting desirable future conditions in light of climatic changes."

    Page 251: "Lastly, assisted migration demonstrates the flaw in relying on absolute dichotomies such as native/exotic and natural/artificial as core features of managing biological systems under global climate change. Though such complete dualism has the advantage of simplicity, it is neither accurate nor helpful in deliberations over how to manage and choose among resources as ecological systems change with climatic conditions. Dedicating substantial resources to preserving and restoring a particular biological unit because it existed at one point in time in an ecosystem makes little sense if climatic conditions make the landscape inhospitable to that unit. Similarly, what is the ethical or scientific justification for prohibiting or removing any organism simply because it never existed in a particular location, especially if that organism is now well‐matched with the location due to changes in climatic conditions?"

    Page 253: "Though this Article provides a preliminary framework for assessing both when to allow and how to manage experimentation with assisted migration, it more importantly explains how climate change reveals a host of value questions that remain unexplored in natural resource law and policy. The resolution of these questions will shape not only determinations regarding the acceptability of assisted migration, but more broadly the future of natural resource management."

    Page 255: "In summary, a regulatory framework that fosters open and transparent access, debate, and deliberation can promote agency accountability to democratic representatives and the general public, and more informed public deliberation and action with regard to the management tradeoffs that must be made in devising goals and sandards for natural resource management. Though developing such institutions and processes will be far from easy, such a pursuit unquestionably should be the focus of natural resource law in a world of rapid climate change. The prior account of a pristine and untouched nature may be nearing its end. However, the opportunity to help foster biotic and human communities that truly integrate humanity's collective self-interest in resource conservation and duties of stewardship has really just begun."

    SEE ALSO: "Assisted Migration: A Viable Conservation Srategry to Preserve the Biodiversity of Threatened Island Nations?", by Jessica Wentz, 2011, Columbia Law School Working Paper.

  • "Using assisted colonisation to conserve biodiversity and restore ecosystem function under climate change" by Ian D. Lunt et al, Biological Conservation, Vol 157, 2013
    EXCERPT: "To date, the assisted colonisation literature has focused primarily on a single rationale: to enhance the survival prospects of the taxon being moved, or small numbers of interdependent taxa, such as butterflies and host plants (Hellmann, 2002). However, here we suggest that assisted colonisation could also be undertaken to achieve a very different conservation goal — to maintain declining ecosystem processes. Adopting the terminology of Seddon (2010), this type of assisted colonisation would be classified as ecological replacement — the release of "a species outside its historic range in order to fill an ecological niche left vacant by the extirpation of a native species", and is akin to the "anticipatory restoration" activities proposed by Manning et al. (2009). This goal may become prominent in future climate change adaptation programs as the impacts of climate change become more severe, but the juxtaposition of goals has not been considered in the assisted colonisation literature and demands benefit-risk evaluation.
        "For simplicity, we characterize these two contrasting rationales for assisted colonisation as 'push' and 'pull' strategies. Push strategies that focus on conserving individual taxa or small groups of inter-dependent taxa are already widely discussed in the assisted colonisation literature. In these cases, issues such as rarity and threat guide the selection of target taxa, and populations are 'pushed' into one or more localities where it is expected that they will maintain viable populations for an extended period under climate change (e.g. Willis et al., 2009). Risk assessments are required to ensure that informed decisions are made to relocate taxa such that there is minimal impact on other species where they are introduced (Burbidge et al., 2011). In contrast, assisted colonisation that is also motivated by a desire to restore ecosystem function should expect to have an appreciable impact at the recipient site. In such 'pull' scenarios, desired ecosystem functions and potential recipient sites would first be identified, and appropriate candidate species would then be 'pulled' into recipient sites to maintain or restore the specified function. Relocation of taxa may be undertaken to deliver ecological functions that are directly affected by climate change, or where climate change exacerbates other causes of decline."

  • "Projected Climate-Driven Faunal Movement Routes" by J. J. Lawler et al., Ecology Letters 2013
    ABSTRACT: Historically, many species moved great distances as climates changed. However, modern movements will be limited by the patterns of human-dominated landscapes. Here, we use a combination of projected climate-driven shifts in the distributions of 2903 vertebrate species, estimated current human impacts on the landscape, and movement models, to determine through which areas in the western hemisphere species will likely need to move to track suitable climates. Our results reveal areas with projected high densities of climate-driven movements — including, the Amazon Basin, the southeastern United States and southeastern Brazil. Some of these regions, such as southern Bolivia and northern Paraguay, contain relatively intact landscapes, whereas others such as the southeastern United States and Brazil are heavily impacted by human activities. Thus, these results highlight both critical areas for protecting lands that will foster movement, and barriers where human land-use activities will likely impede climate-driven shifts in species distributions.
         EDITOR'S NOTE: The 2,903 vertebrate species modeled do not include any species for which bioclimatic projections indicate that discontinuities in livable landscapes will block easy species movements to respond to climate change. Hence, those vertebrate species that may require human-assisted migration were excluded from the study results.
         EXCERPTS: "The southern Appalachian Mountains in the southeastern United States and the Atlantic Forest in Brazil were two prominent areas highlighted by our models as likely to have high concentrations of species movements. Both of these areas are suspected to have served as climate refugia in the past." . . . "Our models do not account for dispersal distances and thus some of the movements included in our results may be unrealistic as they may be in areas that a given species will not be able to reach in a 100-year period. Many moles, shrews and primates, for example, may not be able to disperse fast enough to keep pace with climate change in the Western Hemisphere (Schloss et al. 2012)."

  • "Restoration Ecology" blogpost by Julissa Roncal, 7 July 2012
    EXCERPT: As a plant ecologist at Fairchild Tropical Botanic Garden I was part of a team led by Dr. Joyce Maschinski working on the conservation and restoration of endangered species in South Florida. We addressed questions like: Can endangered species be translocated outside their historic distribution range? Have the fundamental and realized niches changed due to anthropogenic influence? Does the new suitable habitat support favorable biotic interactions? What should be the genetic source to establish new populations? Do seeds, seedlings, cuttings, or adults are better transplant material? We conducted experimental introductions of several endangered species to answer these questions, and to reduce extinction risk, learn more about the biology of rare species, and advance restoration ecology theory. Our experimental results indicated that the species Amorpha herbacea (Fabaceae) can be translocated outside its known historic range, however, highest growth was attained on a different microhabitat than was historically known, reflecting the influence of anthropogenic disturbance on native plants' future optimal habitat.

  • "Review of science-based assessments of species vulnerability: Contributions to decision-making for assisted migration" by Tannis Beardmore and Richard Winder, 2011, The Forestry Chronicle - The following tools (for assessing potential for assisted migration) are discussed in relation to their use in Canada: (1) the NatureServe Climate Change Vulnerability Index; (2) the System for Assessing Vulnerability of Species to Climate Change (SAVS); (3) the Forest Tree Genetic Risk Assessment; (4) the Index for Predicting Tree Species Vulnerability; (5) ecological standards developed for the assisted migration of Torreya taxifolia; and (6) the Seeds of Success Program.
    EXCERPT: "This example [Torreya Guardians] of assisted migration has raised the issue of authorization and oversight as the official federal recovery plan does not identify assisted migration as a conservation strategy for Florida Torreya. The momentum that this group has created resulted in the U.S. Fish and Wildlife Service considering whether assisted migration is an appropriate strategy for this species (U.S. Fish and Wildlife Service 2010). It is yet to be seen if official plans will include a more thorough assess- ment of the ecological impacts of assisted migration, or more extensive monitoring programs. Nonetheless, this is a very interesting example of how a grassroots organization can pro- pel assisted migration into the forefront, causing a govern- mental agency to consider the use of this strategy."

  • "Why We Disagree about Assisted Migration: Ethical Implications of a Key Debate Regarding the Future of Canada's Forests" by I. Aubin et al., 2011, The Forestry Chronicle - "Although human-mediated movements are not a recent phenomenon, assisted migration has lately been the source of debate, in particular within conservation biology circles. In this paper, we outline the major perspectives that help define differing views on assisted migration and shed some light on the ethical roots of the debate in the context of Canadian forests."

  • "Testing alternative models of climate-mediated extirpations?"(American Pika) by Erik A. Beever et. al, Ecological Applications January 2010
    EXCERPT: "Research on American pikas (Ochotona princeps) in montane areas of the Great Basin during 1994-1999 suggested that 20th-century population extirpations were predicted by a combination of biogeographic, anthropogenic, and especially climatic factors. Surveys during 2005-2007 documented additional extirpations and within-site shifts of pika distributions at remaining sites."
        Editor's Note: See also the 2012, "Not-so-splendid isolation: modeling climate-mediated range collapse of a montane mammal Ochotona princeps [American pica] across numerous ecoregions", which includes "Nineteen of the 31 traditional US pika subspecies were predicted to lose > 98% of their suitable habitat under a 7 degree C increase in the mean temperature of the warmest quarter of the year, and lineages were predicted to lose 88 95% of suitable habitat. Under a 4 degree C increase, traditional subspecies averaged a predicted 73% (range = 44-99%) reduction." SEE ALSO 2012 book chapter by Chris Ray et. al, "Retreat of the Amerian Pika: Up the Mountain or into the Void?", which includes: "The majority of evidence for effects of climate on O. princeps derives from studies within the Great Basin . . . In this region, the species has been losing ground for at least 10,000 years: the minimum elevation of the pika's distribution has retracted upslope by nearly 800 meters once the last glacial maximum, eliminating some populations and isolating others."

  • "Can Vulnerable Species Outrun Climate Change?" by Emma Marris, Environment 360 3 November 2011
    EXCERPT: "Reagan Early says that before she completed her research [on the California Newt], she believed that physically moving species to help them reach suitable habitat — a strategy called 'managed relocation' or 'assisted migration' — was a bad idea. But the maps she made [of regional speeds of climate change during the past glacial], with those yawning gaps between the amphibians and the places where they could live happily in the future, changed her mind."

  • "Assisted Migration may save some species from climate change doom" by Thomas B. Smith, Los Angeles Times (op-ed) 21 September 2014

  • "How Fast Can Trees Migrate?" by Jacquelyn Gill, (blogpost) 8 May 2013
    Excellent overview with online links to the recent history, challenges, opportunities, and current issues on this question — especially drawing from the paleoecological literature focusing on pollen data.

  • "Forests Not Keeping Pace with Climate Change" by Zhu, Woodall, and Clark, Global Change Biology, November 2011
    EXCERPT of press release: The study found no consistent evidence that population spread is greatest in areas where climate has changed the most; nor do the species' response patterns appear to be related to seed size or dispersal characteristics. "Warm zones have shifted northward by up to 100 kilometers in some parts of the eastern United States, but our results do not inspire confidence that tree populations are tracking those changes," says Clark, who also holds appointments at Duke as a professor of biology and statistics. "This increases the risk of serious lags in tree migrations."

  • "Assisted migration could help plants find a new home" by Laura Nielsen (for Frontier Scientists blog in) Anchorage Daily News, 28 August 2013
    Excellent short overview of the current discussion on assisted migration, with some examples from northern plant biomes.

  • "Past and ongoing shifts in Joshua tree distribution support future modeled range contraction" by Kenneth L. Cole et al., Ecological Applications, 2011.
    EXCERPT: The future distribution of the Joshua tree (Yucca brevifolia) is projected by combining a geostatistical analysis of 20th-century climates over its current range, future modeled climates, and paleoecological data showing its response to a past similar climate change. As climate rapidly warmed 11,700 years ago, the range of Joshua tree contracted, leaving only the populations near what had been its northernmost limit. Its ability to spread northward into new suitable habitats after this time may have been inhibited by the somewhat earlier extinction of megafaunal dispersers, especially the Shasta ground sloth. All of the models project the future elimination of Joshua tree throughout most of the southern portions of its current range. Although estimates of future monthly precipitation differ between the models, these changes are outweighed by large increases in temperature common to all the models. Only a few populations within the current range are predicted to be sustainable. Several models project significant potential future expansion into new areas beyond the current range, but the species' historical and current rates of dispersal would seem to prevent natural expansion into these new areas. Several areas are predicted to be potential sites for relocation/ assisted migration.
         The Joshua tree example used here does have an added complication in that its migrational capacity to respond to changing climates seems to be extremely limited. There are no historical records of Joshua tree invasions into new habitat and even few documented instances of recent seedling establishment. Although the rapidly warming climate of the early Holocene (Steffensen et al. 2008, Cole 2010) would seem to have opened up vast new areas of potential range to the north, the fossil record does not record any significant northward expansion over the last 11,700 years. These facts coalesce with morphological observations of the plant's indehiscent fruits and the abundance of fruits and seeds in fossil ground sloth dung to support the concept that the species' current mobility is constrained by the earlier extinction of the Shasta ground sloth and other possible seed vector(s) (Janzen and Martin 1982, Lenz 2001).
         Although it is likely that some of these un-sampled areas with high levels of future climate potential, such as Nellis Air Force Base, are already occupied by Joshua tree, they could serve an important conservation function in the future. But other areas further from the current range in central Nevada, northwestern Arizona, and southwestern Utah could hold high potential for future relocation efforts, should such activities prove desirable and possible. Managed relocation, also known as assisted migration or assisted colonization, has become a controversial topic for conservation (Hoegh-Guldberg et al. 2008). Fortunately for Joshua tree, a majority of the areas predicted to be sustainable, within migrational range, or potential assisted migration sites, are already on federal lands or other protected areas.

    See also USGS press release: "Uncertain Future for Joshua Trees Projected with Climate Change".

    A superb 2013 photo-essay including staff interviews at Joshua Tree National Park is "Preventing a Joshua Treeless National Park".

  • "Reframing the Debate Over Assisted Colonization" by Joshua J. Lawler and Julian D. Olen, Frontiers in Ecology 24 March 2011
    EXCERPT: "In light of the difficulty in weighing the consequences of action versus inaction [re assisted colonization], we conclude that focusing the debate on this issue is counterproductive. In fact, we would argue that, given the magnitude of change that is likely to occur in many receiving ecosystems, there is little use in worrying about the effects of introducing one particular species. This is not to say that we should aban- don efforts to assess potential impacts to the receiving ecosystems. However, it does suggest that we consider the amount of change forecast for that ecosystem before conducting detailed experiments on a system that may not exist in the future."

  • "Hope in the Age of Man" by Emma Marris, Peter Kareiva, Joseph Mascaro, and Erle C. Ellis, New York Times 7 December 2011
    EXCERPT: "We can accept the reality of humanity's reshaping of the environment without giving up in despair. We can, and we should, consider actively moving species at risk of extinction from climate change. We can design ecosystems to maintain wildlife, filter water and sequester carbon. We can restore once magnificent ecosystems like Yellowstone and the Gulf of Mexico to new glories — but glories that still contain a heavy hand of man. We can fight sprawl and mindless development even as we cherish the exuberant nature that can increasingly be found in our own cities, from native gardens to green roofs. And we can do this even as we continue to fight for international agreements on limiting the greenhouses gases that are warming the planet. The Anthropocene does not represent the failure of environmentalism. It is the stage on which a new, more positive and forward-looking environmentalism can be built. This is the Earth we have created, and we have a duty, as a species, to protect it and manage it with love and intelligence. It is not ruined. It is beautiful still, and can be even more beautiful, if we work together and care for it."<

    EDITOR'S NOTE: For an opposing viewpoint, see "Conservation in the Anthropocene" by Tim Caro et al., Conservation Biology 2011.

  • VIDEO: Native Peoples Consider Assisted Migration of Plants (2012)

    Beginning at 10:18 into this United Nations video (featuring indigenous awareness of climate change around the world), mention is made of how native peoples in the USA are already looking a hundred or more miles south in order "to see what plants are similar to the plants that are thriving today, because those plants may no longer thrive on their reservation tomorrow. They are looking to see what relatives they may be able to move, to assist, from other places."

  • "The Debate about Assisted Migration" by Extension: America's Research-based Learning Network, 2012
    EXCERPT: This so-called assisted migration of species remains controversial among forest managers, with most favoring one of three distinct policy options: (1) Support aggressive assisted migration; (2) Oppose assisted migration; (3) Support exploring assisted migration.

  • "8 Wild Proposals to Relocate Endangered Species" by Brandon Keim, Wired Science 1 February 2012
    The 8 proposals are for "assisted migration" and/or "rewilding" of: (1) Komodo Dragons and elephants to Australia (the former to predate on alien herbivores; the latter to graze down the fire-prone overgrowth of alien grasses). (2) Rewilding America's Great Plains with proxy herbivores and carnivores from Africa that are close kin of America's own beasts that went extinct at the end of the Pleistocene. A specific example would be (3) Bring Back the Cheetah to America's plains, where a larger cheetah (that went extinct 13,000 years ago) had co-evolved with America's unique pronghorn — the fastest hoofed mammal on Earth. (4) Saving Torreya taxifolia conifer trees, which are too sickly to reproduce in their historic range in northern Florida, by planting seedlings in the mountains of North Carolina (an action already undertaken and apparently succeeding). (5) Antarctic Polar Bears? is the least serious of any proposal, as it would have dire consequences for land-breeding penguins. (6) Whitebark Pine in the western USA, dying in part owing to rapid climate change. (7) Madagascan lemurs to a Caribbean island, to be financed by billiionaire Richard Branson. (8) Aldabran Tortoises to islands in the Indian Ocean a project advocated in 1874 by Charles Darwin and continuing with fresh impetus today — especially to islands in which closely related giant tortoises were hunted to extinction by humans.

  • "Britain Should Welcome Climate Refugee Species" by Chris Thomas, New Scientist 2 November 2011
    Popular adaptation of "Translocation of species, climate change, and the end of trying to recreate past ecological communities", an opinion piece in Trends in Ecology and Evolution, 15 March 2011. EXCERPT: "Britain is already home to around 2000 introduced species which have increased biodiversity while causing few, if any, major problems. True, there have been ecological changes, and we spend a lot of money trying to get rid of aliens, but Britain appears virtually immune to extinctions from introduced species. It therefore represents an ideal destination for endangered species from elsewhere in Europe. One is the Iberian lynx, the most endangered cat in the world. Establishing it in Britain would represent a great contribution to global conservation. Another is the Spanish imperial eagle; a third possibility is the Pyrenean desman, a semi-aquatic mammal restricted to streams in north-west Iberia. Various butterflies and water beetles might also find a suitable home in Britain. In fact, the vast majority of species endangered by climate change are likely to be plants and insects that would be relatively easy to accommodate. . . Conservation is now about managing change. Retaining or restoring the past is no longer feasible. We should avoid the unproductive question 'how can we keep things as they are?' and instead ask 'how can we maximise our contributions to global conservation?' One way will be to open our doors to endangered aliens."
        NOTE: See also, "Experts strive to re-introduce Norfolk's lost species" (reintroduction from Sweden of the pool frog that went extinct in the UK in 1993).

  • "Tending to Our Rambunctious Garden" Q&A with journalist Emma Marris, OnEarth 28 September 2011
    Emma Marris's 2011 book, Rambunctious Garden, has "Assisted Migration" as the topic and title for chapter 5. The Q&A linked above is an excellent short introduction to the reach of this book in highlighting the shifting norms and values in conservation biology and land management today. Assisted migration advocate Connie Barlow posted a positive review of the book on Amazon: "Rewilding, Assisted Migration, Ecological Restoration, and More". There's also an excellent dot-Earth video interview of Marris on youtube.

  • "The Age of Man Is Not a Disaster" - Op-ed by Emma Marris, Peter Kareiva, Erle C Ellis, New York Times 7 December 2011
    EXCERPT: "We can accept the reality of humanity's reshaping of the environment without giving up in despair. We can, and we should, consider actively moving species at risk of extinction from climate change."

  • "Regulate Trade in Rare Plants" by Patrick D. Shirey and Gary A. Lamberti, Nature 27 January 2011
    A groundbreaking "Comment" paper in one of the top science journals combines data analysis of 753 threatened or endangered PLANTS in the USA with policy and legal analysis of the as-yet largely unregulated trade in seeds and seedlings cultivated in private gardens and nurseries outside of the official native habitat. A very readable and thought-provoking exposition of pros and cons of business as usual, now that climate change is motivating conservationists (individually and in groups outside of government) to consider whether the imperiled plant species that they love might benefit from, or even require, their assistance ("assisted migration") — given that governmentally agencies are still hesitant to (and in some cases, prohibited from) expanding locations for conservation programs beyond so-called native range. The work of Torreya Guardians is highlighted, including a 2010 revision in the official ESA management plan for Torreya taxifolia, directing plan managers to attempt to coordinate activities with Torreya Guardians, where possible. The authors conclude: "Although the redistribution of plant species around the world is nothing new, the ease with which people can now obtain and transfer specimens is unprecedented. This, combined with a growing interest in assisted colonization, makes it more important than ever for federal and local governments to wrest control of illegal Internet trade, develop a policy for hybrids and ensure that genetic diversity is considered when propagating plants. 3 pages in PDF for purchase online.

    News articles on this paper: in Science Daily; Los Angeles Times.

    Note: In 2013 the Shirey et al. published a much more complete report on the same topic: "Commercial trade of federally listed threatened and endangered plants in the United States" (published in the Sept/Oct issue of Conservation Letters.

    Note: The authors, Shirey and Lamberti, published another primary resource on the issue of assisted migration in 2010. Scroll below to the title "Assisted Colonization Under the U.S. Endangered Species Act."

  • "Move it or lose it? The ecological ethics of relocating species under climate change" by Ben Minteer and James Collins, Ecological Applications October 2010
    Lead author Ben Minteer is an environmental ethicist, and this paper is a strong and compelling piece of well-supported advocacy in favor of "managed relocation" (aka "assisted migration). The final paragraph reads: "If we value wild species and wish to bequeath a significant fraction of global biodiversity to future generations, radical strategies like managed relocation may well be our last best chance. Although risky, such bold efforts to preemptively move threatened species to new environments may offer the only hope to keep them from moving into museums and zoos—and haunting our ecological conscience." 4 pages in PDF.

  • "Future Human Intervention in Ecosystems and the Critical Role for Evolutionary Biology" by Jessica J. Hellmann and M.E. Pfrender, Conservation Biology December 2011
    EXCERPT: "We expect that considerable philosophical and conceptual change will occur within conservation biology over the next 25 years. If we acknowledge that the human population is growing and that the rapid pace of global change, including climate change, will continue, then we need to begin managing systems that are constantly changing — we can no longer look to the past for guidance on how an ecosystem is supposed to be."

  • "Guardian Angels" article by Janet Marinelli, Audubon Magazine, May/June 2010.
    In-depth exploration of "the biggest controversy in contemporary conservation science." Engagingly written for both a popular and professional audience, journalist Marinelli draws from her interviews with leading scientists, horticulturalists, and activists to present the core arguments for and against assisted migration. A site visit to an endangered plant breeding facility (the Atlanta Botanical Garden) is paired in the article with Marinelli's eye-witness description of "eco-vigilante" action, when the loose-knit citizens group Torreya Guardians intentionally planted into forested landscapes of mountainous North Carolina 31 seedlings of the highly endangered Florida Torreya — an assisted migration of some 400 miles northward of historically known native habitat.

  • "Paleoecology and the Assisted Migration Debate: Why a Deep-Time Perspective Is Vital" online essay by Torreya Guardian Connie Barlow, February 2011.
    Connie Barlow (with assistance from Russell Regnery) has posted a short, 11-point summary essay that aggregates the data and develops strong scientific reasoning in favor of assisted migration for Torreya taxifolia. The essay also advocates a shift in the foundational paradigm from assuming 1491 is the proper time-standard for assessing native range to a "deep-time" perspective grounded in a paleoecological understanding that native ranges for all plants in temperate latitudes of the Northern Hemisphere have undergone substantial altitudinal and/or latitudinal migrations that have tracked changes in climate during the past several million years of Pleistocene glacial and interglacial cycles.

  • "Climate Change and Forests of the Future: Managing in the Face of Uncertainty,", by Constance I. Millar et al., Ecological Adaptations, 2007.
    EXCERPT: Establish 'neo-native' forests. Information from historical species ranges and responses to climate change can provide unique insight about species responses, ecological tolerances, and potential new habitats. Areas that supported species in the past under similar conditions to those projected for the future might be considered sites for 'neo-native' stands of the species. These may even be outside the current species range, in locations where the species would otherwise be considered exotic. For instance, Monterey pine (Pinus radiata), endangered throughout its small native range, has naturalized along the north coast of California distant from its present native distribution. Much of this area was paleohistorical range for the pine, extant during climate conditions that have been interpreted to be similar to expected futures in California. Using these locations for 'neo-native' conservation stands, rather than removing trees as undesired invasives, is an example of how management could accommodate climate change. (p. 2148)

  • "Taking Wildness in Hand: Rescuing Species" article by Michelle Nijhuis, Orion Magazine, May/June 2008.
    A lengthy and elegant feature article that explores the human side of the controversy over assisted migration, with Torreya taxifolia providing the focal point, pro and con, and with actions by the citizen group Torreya Guardians stirring the brew. Comments page accessible through the foregoing link to Orion magazine.

  • "Multidimensional Evaluation of Managed Relocation" 22-author paper by David M. Richardson et al, Proceedings National Academy of Sciences, May 2009.
    ABSTRACT: Managed relocation (MR) has rapidly emerged as a potential intervention strategy in the toolbox of biodiversity management under climate change. Previous authors have suggested that MR (also referred to as assisted colonization, assisted migration, or assisted translocation) could be a last-alternative option after interrogating a linear decision tree. We argue that numerous interacting and value-laden considerations demand a more inclusive strategy for evaluating MR. The pace of modern climate change demands decision making with imperfect information, and tools that elucidate this uncertainty and integrate scientific information and social values are urgently needed. We present a heuristic tool that incorporates both ecological and social criteria in a multidimensional decision-making framework. For visualization purposes, we collapse these criteria into 4 classes that can be depicted in graphical 2-D space. This framework offers a pragmatic approach for summarizing key dimensions of MR: capturing uncertainty in the evaluation criteria, creating transparency in the evaluation process, and recognizing the inherent tradeoffs that different stakeholders bring to evaluation of MR and its alternatives. [Ed. note: This paper is the product of the Managed Relocation Working Group project. Details of three species-specific case studies, including pro and con managed relocation of Florida Torreya, are described in a supplementary pdf. Click the url at the bottom right of page 1 of the pdf of the main paper.]

    Read the National Science Foundation press release of the above article, where you can also access short VIDEOS of Jessica Hellmann talking about the importance of managed relocation.


    Best Review Articles:

    ♦ SOCIETY OF AMERICAN FORESTERS REVIEW ARTICLE (2013): "Preparing for Climate Change: Forestry and Assisted Migration", by Mary I Williams and R. Kasten Dumroese, in Journal of Forestry, July 2013.

    SUMMARY QUOTE: "Climate is changing at a faster pace than natural plant migration, which poses a major challenge to forest management and conservation. We can draw from a century of forest research and management to curtail losses in forest growth, productivity, and conservation by implementing strategies, such as assisted migration. Even though we have seed transfer guidelines and seed zones for many commercial tree species, we lack clear, standard operating procedures to determine how, when, and where to implement movement. Movements outside current guidelines and zones may run afoul of legal restrictions and state and federal directives, but facilitating climatic adaptation through assisted migration has the potential to preserve forest health and productivity, subsequently maintaining ecosystem services, such as carbon sequestration, soil and water conservation, timber, and wildlife habitat. Our review and presentation of current information for researchers, foresters, landowners, and nurseries provides components to consider in their climate change adaptation plans." EXAMPLE: "Alberta is considering ponderosa pine (Pinus ponderosa) and Douglas-fir, now absent in the province, as replacements for lodgepole pine (Pinus contorta) because it is predicted to decline in productivity or suffer from extinction under climate change."

    Editor's Note: The above article is ideal for learning the historical and policy reasons why commercial and public foresters are generally accepting of and at ease with "assisted migration" strategies for coping with anticipated climate change, as applied to populous (and also commercial) tree species. In contrast, resource managers responsible for endangered species and restoration of botanically targeted conservation lands are far more cautious about adopting (even considering) assisted migration as a management tool.

    See also Williams and Dumroese 2013, "Climatic Change and Assisted Migration: Strategic Options for Forest and Conservation Nurseries". A very readable version by the same authors, but intended for land managers and the nurseries that supply seedlings was published in 2014: "Planning the Future's Forests with Assisted Migration".

    Also, "Placing Forestry in the Assisted Migration Debate", by John H. Pedlar et al, 2012, Bioscience. Also: "An Overview of Some Concepts, Potentials, Issues, and Realities of Assisted Migration for Climate Change Adaptation in Forests", by Louis R. Iverson et al., 2013. This latter document distinguishes between two forms of assisted migration: Species Rescue AM v. Ecosystem Services AM; it concludes that the latter is less problematic and has "been underway for centuries" by foresters. (Example of black oak AM into northern Wisconsin under consideration to cope with expected climate change.) For a review of how well U.S. Forest Service policy statements prepare that institution to engage in "assisted migration" rapidly and extensively enough to track expected climate change, see "Policy and Strategy Considerations for Assisted Migration on USDA Forest Service Lands", 2013, Randy Johnson et al. One conclusion is that existing policy "statements imply that the only instance one should engage in assisted migration on an operational basis is when past scientific research supports success. In addition, untested assisted migration can take place if it is part of a research or administrative study. In all cases, monitoring is required. Presently, this limits operational assisted migration to only the handful of species that have provenance trial data available from longer-term field trials and those species where seed sources have been moved previously."

    "Can Boreal and Temperate Forest Management be Adapted to the Uncertainties of 21st Century Climate Change?" by Andrew Park et al., 2014, Critical Reviews in Plant Science. This 35-page pdf by professional foresters from Canada, the UK, and USA is a stunning review of how the profession must evolve given rapid ongoing climate change. It is highly technical and covers concerns and practices far broader than assisted migration — including epigenetic effects of the climates where seed embryos develop and a survey of the pros and cons of various bioclimatic envelope modeling for predicting future preferred habitats on a species-by-species basis. But here are some of the assisted migration excerpts:
    "'Options Forestry' implies that we should simultaneously explore acclimation to higher temperatures among trees already in place, and the possibility that assisted migration (AM) of species to areas where they are not endemic will be needed to adapt to extreme warming. The AMAT experiment is aimed at establishing whether such transfers are possible across a wide temperature range and latitudinal gradient. The southernmost provenances in this experiment will be shifted by as much as 9.1 degrees C and over 2500 mm of precipitation relative to their native climates, and seed will be shifted up to 10 degrees of latitude from their origin (O'Neill et al., 2011). Both climatic and phenological limits will therefore be probed in this experiment.
         Assisted migration is controversial in North America (McLachlan et al., 2007; Minteer and Collins, 2010; Aubin et al., 2011), but in fact has been widely practiced in forestry for at least two centuries. In the UK, exotics such as Sitka spruce and Corsican pine (Pinus contorta var. maritima) comprise 66% of planted forests. These species are now essentially naturalized and are an important component of UK conservation strategies (Humphrey et al., 2003). In GERMANY, trials dating from 1880 show that red oak, Douglas fir, western red cedar, grand fir, and black locust [all North American trees] perform well under local climates. Currently, other non-endemic species are being assessed for their suitability for use in experimental silviculture (Bolte et al., 2006). In CANADA, European and non-endemic native conifers, including lodgepole pine, red, Scots, and ponderosa pines, Siberian larch, and blue spruce have been planted in upland forest "islands" in Canadian prairies since the 1920s. Some of these have grown to considerable size; for example, a 75-year-old red pine plantation was measured at 40 cm average dbh and 26 m in height (Bendzsak, 2006).
         Trees shifted latitudinally by 5 degrees C or more may be vulnerable to both weather extremes and normal weather variations in their new environment, especially during the seedling stage. These extremes can be buffered by establishing new species in shade of existing canopies, which can also mitigate competition from non-target species (Cameron and Watson, 1999). Underplanted species generally require more light as they grow (Messier et al., 1999), but tolerate a broader range of climate extremes as they mature (Jackson et al., 2009). Eventually partial or complete removal of the original overstory could be required to allow underplanted species to mature successfully. The timing, volume, and spatial pattern of overstory release will vary according to the desired balance between buffering weather extremes, maintaining soil water supplies, understory light levels and other site characteristics.
         No-analogue climates may demand development of no-analogue, designer, or "neonative" plantations in which trees are selected for their potential to combine compatible functional effect and response traits (SchererLorenzen et al., 2007). For example, because down-regulation of photosynthesis in elevated CO2 could be induced by nitrogen limitations (Franklin, 2007), intimate mixtures that include nitrogen-fixing trees and shrubs provide a potential means to leverage carbon fertilization effects. Nitrogen-fixing (e.g., alder species) and non-nitrogen fixing trees could and are already combined in mixed stands (e.g., Parrotta, 1999; Binkley et al., 2003; Maas-Hebner et al., 2005). For example, common (European) walnut (Juglans regia L.) has 22% to 80% better height growth when planted in intimate mixtures with nurse trees (e.g. western red cedar) and a nitrogen-fixing shrub (autumn olive), relative to walnut planted alone or with only a nurse tree (Clark et al., 2008).

    ♦ 2012 ARTICLE ON EVEN COMMON TREES IN AMERICA'S FORESTS ARE LAGGING BEHIND THE PACE OF CLIMATE CHANGE: "Tracking suitable habitat for tree populations under climate change in western North America" - by Laura K. Gray and Andreas Hamann, 2012, Climatic Change. EXCERPTS:

       We find that, on average, populations already lag behind their optimal climate niche by approximately 130 km in latitude, or 60 m in elevation. For the 2020s we expect an average lag of approximately 310 km in latitude or 140 m in elevation, with the most pronounced geographic lags in the Rocky Mountains and the boreal forest. We show that our results could in principle be applied to guide assisted migration of planting stock in reforestation programs using a general formula where 100 km north shift is equivalent to approximately 44 m upward shift in elevation. However, additional non-climatic factors should be considered when matching reforestation stock to suitable planting environments.
        . . . In widespread tree species, genetically differentiated populations are uniquely and often narrowly adapted to their local environments. Hence, climate change impacts will not be limited to the trailing edge of a species range, but instead may apply to populations throughout the species range. . . For species and population level analysis we selected 15 major forest tree species of commercial importance in western North America.


       In 2008, the Climate Change Resource Center of the U.S. Forest Service assembled a dozen research foresters at the leading edge of translating climate change science into "adaptation" responses for forest managers. These scientists delivered excellent short talks captured on video. The result is a superb, free online learning tool: ADAPTING TO CLIMATE CHANGE: A Short Course for Land Managers". "Assisted Migration" as an important adaptation strategy for foresters is specifically mentioned by Constance Millar. Similarly, Jill Baron encourages experimentation (in which lack of success in small-scale adaptation projects would be regarded as helpful learning experiences, not failures).


    Note: The "current" ranges of each species used in the following USDA climate model maps are drawn from the classic USDA species range maps prepared by Elbert Little from 1971-77. You can access those original maps here: ""Atlas of United States Trees" by Elbert L. Little, Jr".

  • WESTERN USA:"Plant Species and Climate Profile Predictions". Highly detailed online maps to compare current, 2030, 2060, and 2090 range predictions for 76 species of western USA trees. (Always click on the .png versions to see the maps.) For example, Alligator Juniper, now absent from Colorado, is expected to have ideal range open up west of Denver in 2030, while southerly populations become stressed. (How are they going to get there, as the closest current population is near Santa Fe NM?) Note: A superb paper that details the data-source and modeling used to generate these range maps is "North American Vegetation Model for Land-Use Planning in a Changing Climate", 2012, G.E. Rehfeldt et al.

  • EASTERN USA: Easy-to-use USFS webpage of maps imaging current and climate-shifted ranges of 134 tree species in eastern North America: Climate Change Tree Atlas interactive site (also, a combined Tree and Bird Atlas eastern USA). See also a multi-agency generated Forecasts Maps Projects for the Eastern USA. A 2008 paper by USDA forest researchers (Iverson et al.), published in Forest Ecology and Management, introduces the 134-species online range-map projection tool (professionals must read): "Estimating potential habitat for 134 eastern US tree species under six climate scenarios".
    EXCERPT: "Of the 134 species, approximately 66 species would gain and 54 species would lose at least 10% of their suitable habitat under climate change. A lower emission pathway would result in lower numbers of both losers and gainers. When the mean centers, i.e. center of gravity, of current and potential future habitat are evaluated, most of the species habitat moves generally northeast, up to 800 km in the hottest scenario and highest emissions trajectory. The models suggest a retreat of the spruce-fir zone and an advance of the southern oaks and pines. In any case, our results show that species will have a lot less pressure to move their suitable habitats if we follow the path of lower emissions of greenhouse gases. . . . . . Our predictions of increase in range (potential future suitable habitat) are very likely to be overestimates of the actual ranges that would be achieved by the end of this century, as migration of most species will not keep up with relatively abrupt changes in climate, unless humans get seriously involved in moving species."
    For depth treatment of the modeling strengths and weaknesses, see Iverson et al., 2010, "Potential changes in habitat suitability under climate change: Lessons learned from 15 years of species modelling".

  • WHOLE USA: This forest tree website builds on the previous (above) two, while adding a new feature of color-coded images that show relative difficulties in moving/adapting of different geographic populations of each species. Access here: The ForeCASTS Project, subtitle: Forecasts of Climate-Associated Shifts in Tree Species.

  • Modeling species-specific shifts in geographic ranges in parallel with various climate models has a number of complications one should be aware of. Here is an excellent review paper of these issues: "Adaptation, migration or extirpation: climate change outcomes for tree populations", by Sally N. Aitken et al., 2008, Evolutionary Applications.

  • A highly detailed analysis of the pros and cons of the several approaches to modeling and mapping how "bioclimatic envelopes" for trees will shift under various climate scenarios is "Can Boreal and Temperate Forest Management be Adapted to the Uncertainties of 21st Century Climate Change?" by Andrew Park et al. (the six authors are Canadian, USA, and UK). This 35-page review and analysis was published in 2014 in Critical Reviews in Plant Sciences.

  • A much shorter and less detailed overview of the pros and cons of several types of species-specific climatic range shift models is "Tree-species range shifts in a changing climate: detecting, modeling, assisting", 2013, by Iverson and McKenzie in Landscape Ecology. (Nonprofessionals will want to read this article first before tackling the Park et al. treatise.) Final paragraph:
    We encourage continued research to move the science forward on detecting, modeling, and the potential assisting of actual and potential tree range shifts in a changing climate. Many additional advances will be possible by making continued improvements in the integration among the avenues reviewed here. For example,the merger of process models, demography models, and species distribution models allows for some of the best attributes of each, in working with suitable habitats into which multiple species must migrate, colonize, compete, and successfully reproduce, all at fine temporal and spatial scales. It is an exciting time for research as the computer-based tools, available data, and methods are simultaneously advancing at a remarkable rate. Meanwhile, we must be diligent to continue to provide the natural history and demography studies (=field work!) to provide the fuel for the modeling and interpretation of model outputs. Many species are poorly known as to their reproductive, competitive, ecological, and adaptability capacities, and how these vary under changing climates, including climates novel to their evolutionary history. There will always be plenty of uncertainty, but we cannot let that stifle our endeavors to bring the best science possible to decision-makers and managers to mitigate and adapt to the coming impacts from climate change.


        A September 2014 4-page article, "Have Tree, Will Travel" is a superb way to grasp the paleoecological foundation that undergirds projects for which poleward "assisted migration" on the continent of origin is becoming standard practice in this century of rapid climate change. The author, park planner Kevan Williams, weaves the science and policy viewpoints into three sequential narratives:
        (1) a futile recent Nature Conservancy project of attempting to "rewild" a native camellia, Franklinia alatamaha, southward to its "native" (actually, peak-glacial) habitat in southern Georgia from its cultivated (rescue) domain near Philadelphia.
        (2) the ongoing (and thus far successful) attempt by citizen naturalists to work around the Endangered Species Act and thus on their own initiative move a critically endangered Florida conifer, Torreya taxifolia (photo left), from its peak glacial refuge in northern Florida into the southern Appalachians and points farther north.
        (3) the disaster looming large for even common forest trees, as climate shifts rapidly, along with the role that massive projects of assisted migration, on the one hand, and urban forest landscaping, on the other, could play in helping species move north.

        "Assisted Migration: What It Means to Nursery Managers and Tree Planters" is an excellent short introduction intended for landscapers and their clients, urging that planting for climate change become integral to the profession.

    LEFT: The authors (Williams and Dumroese) distinguish 3 types of assisted migration: (1) Assisted population migration, (2) Assisted range expansion, and (3) Assisted species migration. (Florida Torreya is the illustrated example of type 3.)

  • "Wilderness Conservation in an Era of Global Warming and Invasive Species: a Case Study from Minnesota's Boundary Waters Canoe Area Wilderness" by Lee Frelich and Peter Reich, 2009, in Natural Areas Journal. The concepts in this 9-page pdf are wide-ranging and perhaps alarming to those new to the literature on climate change consequences for American forests. The quality of prose and flow of ideas enable this densely packed paper to be understood even by nonprofessionals. HIGHLY RECOMMENDED! Readily understood terminology is also introduced, as in the distinction between "Local assisted migration" (moving genotypes of tree species to north-facing slopes or other cooler or moister microclimates within its existing range to serve as micro-refugia as climate warms) and "long-distance assisted migration" (the latter broadly encompasses what Williams and Dumroese label in the above figure as "assisted range expansion" and "species assisted migration").
        Wilderness advocates and proponents will want to pay special attention to the subsection, "Wilderness Law and Management Issues. All readers will benefit from contemplating forestry-climate management issues within the rich details of a single case study.

  • "Climate change to Philly trees: It's not 1910 anymore" (news article) by Carolyn Beeler, 23 January 2015. Surveys Philadelphia and Chicago urban trees and parks managers who have already begun planting more southerly tree species on municipal lands. Joan Blaustein, head of urban forestry and ecosystem management at the Philadelphia Parks Department, is quoted: "We need to anticipate what the conditions are going to be 100 years from now, rather than trying to restore to 100 years ago." Beeler writes, "In the fall, the city will plant non-native trees suited to warmer climates, including the Southern chestnut oak and bald cypress, and plant some species native to Pennsylvania that are currently at the northern end of their range, such as the Southern red oak and red mulberry. . . In five years, Blaustein hopes the early results of her experimental test plots will give her an idea of which new trees to plant city-wide."


  • "Forest Responses to Changing Climate: Lessons from the Past and Uncertainty for the Future", 2000, Donald H. DeHayes et al., book chapter in Responses of northern U.S. forests to environmental change.
    EXCERPT: Continent-wide changes in distribution and abundance of plant taxa are species-specific, consistent with Gleason's (1926) individualistic concept of plant-species responses (Davis, 1983; Jacobson et al., 1987). Contrary to popular belief, modern communities are not highly organized, finely tuned units representing long periods of co-evolution among species. Rather, present communities are merely transitory combinations of taxa that have been responding individualistically to continual and sometimes major climate changes (Hunter et al., 1988). [includes "Eastern White Pine Case Study"] Paleoecological evidence shows that eastern white pine made its first post-glacial appearance in Virginia (Craig, 1969), perhaps moving in from a full glacial location on the exposed continental shelf. It reached northern New England by 10,000 years ago (Davis and Jacobson, 1985), the central Great Lakes region by 9,000 years ago (Brubaker, 1975), and Minnesota and western Ontario by 7,000 years ago (Jacobson, 1979; Bjorck, 1985). Eastern white pine reached its northernmost extent about 4,000 years ago, with areas of high abundance shrinking substantially and shifting southward thereafter. This coincides with climate cooling that has allowed boreal taxa to move southward. Another factor in the late-Holocene decline in eastern white pine is the decrease in frequency of fire. Further details of these late-Holocene changes may be found in Jacobson and Dieffenbacher-Krall (1995). The western range limit of eastern white pine occurs today where precipitation equals evapotranspiration (Transeau, 1905). Unless its habitat is manipulated by human activity, white pine does not thrive when conditions become too cool or moist, for example, at the southern margins of the boreal forest in northern New England and adjacent Canada where disturbance by fire may be too infrequent for widespread establishment of seedlings. The current abundance of eastern white pine in the Northeast results largely from abandonment of farmland during the last 150 years.
         Paleoecological studies of the later Holocene show that the boreal forest of eastern Canada developed only in the past 6,000 years (Webb, 1987) and that hemlock has been abundant in the forests of the eastern Great Lakes-New England region for that same period of time (Fig. 14.4). Other data show that southern populations of spruce (Picea spp.) shifted from Canada into the northern tier of states from Maine to Minnesota in the past 1,000 to 1,500 years, accompanied by a general decrease in abundance of eastern white pine that has continued to the present (see Fig. 14.2). Small populations of balsam fir (Abies balsarnea [L.] Mill.) were scattered throughout the northeast during most of the Holocene, but they, too, expanded recently to form the spruce-fir forests of today. The spatial array of changes has been influenced by variations in importance of fire (Foster, 1983) and other disturbances.
        Northern populations of most temperate and boreal zone species have no difficulty tolerating climates more than 5¡C warmer on an annual basis. The only exception may be with trees having substantial winter chilling requirements. For example, red maples from Massachusetts exhibit sporadic and delayed spring budbreak and have poor survival when grown in Florida (Perry and Wang, 1960). This possibility should be examined carefully because some climate models project that much of the future warming will be experienced in the winter (Woodward, 1992). Observations of horticultural plantings also suggest that species can be grown in climates far warmer than any place in their natural range. Coupled with the relatively rapid rate of predicted climate warming, these data and experiences highlight the possibility that many species distributions may not simply shift northward or upward, but may actually remain competitive in their current locations and actually expand their distributions.
         A greater concern is that a warmer and drier environment may reduce germination and seedling survival. The most sensitive stage of a tree's life is the beginning. Losses in this period are very high, owing mostly to conditions that are inhospitable at this vulnerable stage. On sites that are prone to drought or lethal temperatures, such as south-facing slopes, higher temperatures would exacerbate losses. The area affected by these lethal agents would increase to some degree. Furthermore, germination could be reduced or unfavorably delayed in species with unmet cold stratification requirements. These unknown factors related to seed germination and success of the seedling stage in forest trees all contribute to uncertainty in predicting future forest composition.
         Many species found a "glacial refugium" in the southern Appalachian region. If the Appala- chian Mountains were aligned east-west instead of north-south, perhaps many of these species would have been unable to migrate far enough southward to endure the climatic cooling experienced during glaciation.
         Uncertainty exists about the nature and extent of future climatic change and its effect on migration of forest tree species. Although it is tempting to speculate that climate change may be too rapid for forest tree species to successfully migrate or that large gaps may be created that can restrict species dispersal, historical evidence indicates that climate changes in the past have been more rapid than changes projected for the next few centuries without any great restriction to species movement.

  • PALEO DATA USED TO PREDICT SEVERE 21st CENTURY PROBLEMS FOR TREES SHIFTING RANGES: "Pushing the Pace of Tree Species Migration", by Eli Lazarus and Brian McGill, 27 August 2014, PLOS One. Editor's note: This paper deals exclusively with tree species whose seeds are wind-dispersed. The outlook for trees with animal-dispersed seeds is even gloomier. EXCERPT:
    Field measurements of typical seed dispersal distances would suggest that tree fronts migrate across a landscape by a process of local diffusion, at rates significantly slower than the velocities reflected in pollen data. But seeds are occasionally carried long distances from their source by wind or by animals. If those seeds mature into trees that in turn dispense seeds, the plant species may migrate at rates that far exceed diffusive propagation. Existing models of tree migration by long-distance dispersal produce migration rates between approximately 100 to 200 m yr-1. A global analysis of temperature-change rates across geographic gradients and biomes finds that temperate broad-leaf and mixed forests, which includes the North American taxa that spread by wind-blown dispersal, will need to shift at a mean velocity of 350 m yr-1. These required migration rates appear to exceed the fastest modeled rates, but may fall within the ranges empirically observed in the last deglaciation. Migration rates barely sufficient to track with climate, combined with the well-documented effect that landscape fragmentation further impedes migration, points to the apparently unequivocal conclusion that climatic change will outpace the migration of wind-dispersed tree species through human-dominated landscapes. One of the few known cases in which climate-driven species migration was impeded comes from Europe, where east-west mountain ranges and the Mediterranean Sea prevented trees and plants from advancing far enough south during Pleistocene glaciation, resulting in a high proportion of extinction. By extension, understanding how human fragmented landscapes interfere with migration rates might mean the difference between minimal extinction rates and massive extinction rates in next few hundred years.

  • PALEOECOLOGICAL DISTRIBUTION OF E. NORTH AMERICA TREES: "Molecular Indicators of Tree Migration Capacity Under Rapid Climate Change", by McLachlan et al., in Ecology, 2005. CONTENT: Excellent review of paleocological investigations using paleo-pollen, macrofossils, and genetic data to ascertain (a) locations of glacial refuges of N.A. temperate trees during the last glacial maximum, and (b) the northward path and speed of movement as the peak glacial episode began to wane some 18,000 years ago. EXCERPT: "Molecular evidence suggests that American beech (Fagus grandifolia) and red maple (Acer rubrum) persisted during the late glaciation as low-density populations, perhaps within 500 km of the Laurentide Ice Sheet. Because populations were closer to modern range limits than previously thought, postglacial migration rates may have been slower than those inferred from fossil pollen. Our estimated rates of <100 m/yr are consistent with model predictions based on life history and dispersal data, and suggest that past migration rates were substantially slower than the rates that will be needed to track 21st-century warming."

  • CLASSIC PALEOECOLOGY PAPER ON PAST FOREST RESPONSES TO CLIMATE CHANGE: "Range Shifts and Adaptive Responses to Quaternary Climate Change", by Margaret B. Davis and Ruth G. Shaw, 2001, Science. Excerpt: "Although all the tree species that remain in our flora shifted or contracted ranges, adapting to climate changes in the past, there are reasons to question whether these processes will occur as readily during the present period of climate change."

  • CLASSIC FORESTRY PAPER ON THE DIRE PROBLEM OF THIS CENTURY'S SPEED OF CLIMATE CHANGE: "Adaptation, Migration or Extirpation: Climate Change Outcomes for Tree Populations", by Sally N. Aitken et al., in Evolutionary Applications, 2008. EXCERPT: "Findings of relatively slow tree migration rates in response to historical changes in climate (potentially < 100 meters per year) are unfortunate in light of model predictions of how fast tree species will need to migrate to track current climates under climate change scenarios. Tests of 14 combinations of GCMs and global SDMs show up to 100% of the models predicting migration rates of 1000 meters per year or higher to be necessary to track habitat under 2x CO2 climate forcing."

  • HOW NORTH AMERICAN TREES SPECIES AND BIOMES SHIFTED FROM PEAK GLACIAL TO WARM TIMES: "Late-Quaternary Vegetation Dynamics in North America: Scaling from Taxa to Biomes" - John W. Williams et al., Ecological Monographs, 2004. Excerpts: "This paper integrates recent efforts to map the distribution of biomes for the late Quaternary with the detailed evidence that plant species have responded individualistically to climate change at millennial timescales. We show how the individualistic shifts in range and abundance for plant taxa scale upward to cause (1) compositional shifts within plant communities, (2) appearances and disappearances of novel plant associations, and (3) changes in the position, area, composition, and structure of biomes. Modern associations such as Fagus-Tsuga and Picea-Alnus-Betula date to the early Holocene, whereas other associations common to the late-glacial period (e.g., Picea-Cyperaceae-Fraxinus-Ostrya/Carpinus) no longer exist."

  • "RELICT" SPECIES RESTRICTED TO DISJUNCT AND SMALL RANGES BY PLEISTOCENE GLACIALS: In 2012 an exemplary paper was published by forest researchers that demonstrated how a paleoecological perspective is vital to understand the importance of "assisted colonization" as a management tool in this century's time of rapid climate shift: "Projections of suitable habitat under climate change scenarios: Implications for trans-boundary assisted colonization", by Ledig, Rehfeldt, and Jaquish, 2012, American Journal of Botany.
        Importantly, this paper also diminishes fears that such relicts might become invasive: "In part, objections to assisted colonization rest on the fear that exotic translocated species will become invasive and compete with native species or that they will carry new pests or on the esthetic argument that such movements result in a homogenization of the flora (Seddon et al., 2009; Ricciardi and Simberloff 2009a, , 2009b; McLachlan et al., 2007). With regard to the issue of native vs. exotic, spruces have moved north and south across North America over geological time (e.g., discussion in Ledig et al., 2004)."     The focal species of this paper is Brewer Spruce, Picea breweriana, which is limited today to the Klamath region of coastal Oregon/California. The paper finds that projected climate change will necessitate the assisted movement of this unique spruce to coastal British Columbia in 2030 to 2060 and finally to the Yakutat coastal region of Alaska by 2090. Here is how the paper begins (citations eliminated):
    "The western United States was warm, subtropical forest in the Eocene (40 million years ago [Ma]). Above 50 degrees N, about the latitude of Vancouver, British Columbia, Canada, was the Arcto-Tertiary Forest. A species like dawn redwood (Metasequoia) was a common element of the Arcto-Tertiary Forest. Genera like bald cypress (Taxodium) and blackgum (Nyssa), now found only in the southeastern United States, grew along the interface of the Arcto-Tertiary Forest and the subtropical forest. Along the streams in the Arcto-Tertiary Forest were species similar to Port-Orford-cedar [Chamaecyparis lawsoniana (A. Murr.) Parl.] and coast redwood [Sequoia sempervirens (D. Don) Endl.], and species of the genus zelkova (Zelkova). Spruce (Picea), fir (Abies), and maples (Acer) grew on the uplands. Cooling occurred at the end of the Eocene, and by the Oligocene (28 Ma), the Arcto-Tertiary Forest had moved south to occupy the western United States. Mountains, including the Coast Ranges of Oregon and California, the Cascades, Sierra Nevada, Olympic Mountains, and Klamath Mountains, began to form in the Miocene (23 Ma). These ranges created a rain shadow to their east, and the Arcto-Tertiary Forest began to shrink and fragment. New communities formed as old ones segregated along new habitat lines. By the Pliocene, 5 Ma, the rich mesophytic forest was gone and was replaced by woodland, grassland, and desert. Many species went extinct and the closest analogue to the Arcto-Tertiary Forest now exists only in the southeastern United States or eastern Asia. However, California and, to a lesser extent, Oregon became a refuge for some elements of this forest. . . Brewer spruce is a relict of past climate change. According to the fossil record, Brewer spruce had a wide distribution in the Miocene and Pliocene, at least as far east as Idaho and Nevada, north to central Oregon, and south to central California. The fossil species, Sonoma spruce (Picea sonomensis Axelrod), which is synonymous with Brewer spruce, occurred in the Creede Flora in the San Juan Mountains of southwestern Colorado in the Oligocene. As cool, moist forests shrank toward the coast and higher elevations, Brewer spruce became endemic to the Klamath Geomorphological Province, which in the West retains forests most nearly equivalent to the western North American Arcto-Tertiary forests.
        To facilitate the conservation of Brewer spruce and possibly prevent extinction, we have planned a program of assisted colonization through the establishment of carefully managed trial plantations on sites with suitable projected climates in northwestern British Columbia. Because such trans-boundary movements and intergovernmental collaboration may, indeed, be necessary to protect a multitude of species threatened and endangered by climate change, we examined the applicable restrictions and found few or no barriers to assisted colonization."

  • "Paleoecology and the Assisted Migration Debate: Why a Deep-Time Perspective Is Vital" online essay by Torreya Guardian Connie Barlow, February 2011,
    an 11-point summary essay that aggregates the paleoecological data and develops strong scientific reasoning in favor of assisted migration for Torreya taxifolia. The essay also advocates a shift in the foundational paradigm from assuming 1491 is the proper time-standard for assessing native range to a "deep-time" perspective grounded in a paleoecological understanding that native ranges for all plants in temperate latitudes of the Northern Hemisphere have undergone substantial altitudinal and/or latitudinal migrations that have tracked changes in climate during the past several million years of Pleistocene glacial and interglacial cycles.
  • "How Fast Can Trees Migrate?" a PALEOECOLOGICAL PERSPECTIVE by Jacquelyn Gill, (blogpost) 8 May 2013
    EXCERPT: "The simple story of the last 2.5 million years of vegetation response to climate change could be summed up like this: temperature goes up and down, plants go back and forth. We've had over a dozen ice ages and interglacials since the beginning of the Quaternary Period. In response, flora and fauna are repeatedly displaced by the expanding ice sheets and changing climates. As carbon dioxide concentrations approach 400 ppm (any day now) for the first time since the mid-Pliocene, ecologists and conservation biologists turn to the paleorecord to get a sense of how well plants can track their optimal climates."

  • "Niche syndromes, species extinction risks, and management under climate change" by Dov Sax, Regan Early, and Jesse Bellemare in Trends in Ecology and Evolution 2013.
    Although this paper is not substantially paleoecological, it is grounded in the distinction between "fundamental niche" and "realized niche", and applies those concepts to ecological constraints (including seed dispersal limitations) that have resulted in the "realized niche" (known current range) of some species lagging substantially southward of where the climate envelopes of post-glacial "fundamental niches" have likely shifted to. The authors introduce a new concept of "tolerance niche", which could be well applied to "assisted migration" experiments and actions in behalf of tree species. A species living in its "tolerance niche" is not self-sustaining (e.g., it may be able to grow and thrive, but not reproduce). Conservationists acting in advance of climate change could thus aim to establish a species northward into a "tolerance niche" habitat, while expecting ongoing climate change to advance to the point that long-lived tree species eventually are able to reproduce (thus transforming the tolerance niche into both a fundamental and a realized niche for that particular species). Note: See also Bellemare and Moeller "Climate Change and Forest Herbs of Temperate Deciduous Forests (TDF)" for a superb paleoecological review, with implications for conservation when the climate is rapidly changing.


  • "The assisted migration of western larch in British Columbia: A signal of institutional change in forestry in Canada? by Nicole L. Klenk and Brendon M.H. Larson, Global Environmental Change 2014.
    EXCERPTS: Based on 46 interviews with policy actors across Canada, our results suggest that the deployment of the first assisted migration policy in Canada successfully avoided the controversy surrounding the idea in the scientific community by changing the scientific discourse associated with best forest management practices. The shift from an ecological discourse to a genetics discourse over forest policy in British Columbia signals what we might expect in future forest adaptation policy development in Canada.
        Clearly, a genetics characterization of forests looks back to the distant past for guidance in future 'climate change fitness of species'. This represents a major conceptual shift, which significantly affects the temporal and spatial scales on which forest management planning occurs. This shift can be characterized, furthermore, by the deployment of new normative goals for forest management: rather than trying to recreate current forest composition and functions, the values and norms guiding forest management from a genetics perspective seek to accelerate forest transition to the future, to a 'climate resilient' state. This normative shift has real material consequences, such as enabling the movement of western larch 1000 km north of its current distribution, sidestepping the issue of its ecological appropriateness in the recipient ecological community, because from a 'climate fitness' perspective, western larch may eventually migrate to northern BC.
        Thus given the genetical frame structuring the AM policy coordinative discourse, we argue that there is a major shift in the cognitive and normative content of ideas at the program level. However, when we analyzed the communicative discourse on western larch AM policy, we found that concerted efforts were taken by policy developers to downplay the significance of this program change in their communication to the public. To begin, educational and training outreach activities stressed the low risk associated with population range expansion, as the following interviewee explains: "We are very open and inclusive in talking about AM. I talk about the risk of action and inaction and more importantly the difference between the various forms of AM. We are very clear that we are not testing or interested in exotic translocations."
        To sum up, our analysis suggests that policy analysts, forest geneticists and policy implementers in the BC Tree Improvement Branch characterized forests so as to highlight and diffuse an evolutionary theory of forest ecosystems that is tied to a new set of norms and values associated with a humanistic philosophy that are highly controversial in the conservation community—yet which, in turn, are signals of major institutional change in forest policy in BC. . .  Our results suggest that the deployment of the first AM policy in Canada has successfully avoided the philosophical debates on AM in the conservation scientific community by changing the scientific discourse associated with best forest management practices (i.e., from an ecological point of view to a genetics point of view) and this discursive shift may signal what we might expect in future forest adaptation policy development in Canada.

    FORESTS OF CANADA: The government of Canada (Natural Resources Canada) and the Canadian Forest Service each are moving forward with strategies for adapting forests and forest resources to anticipated climate change. Natural Resources Canada maintains a webpage on "Assisted Migration", which as of mid 2013 includes these excerpts: "Forests are climate sensitive, and a range of climate change impacts are already evident across Canada. Trees appear to be responding to warming temperatures by dispersing into more climatically suitable habitats. However, some populations will be unable to keep up with the rapid rate of environmental change. Numerous adaptation options are being considered as ways to maintain the biodiversity, health and productivity of Canada's forests under continued climate change. One option that is of increasing interest is 'assisted migration,' the human-assisted movement of plants or animals to more climatically suitable habitats. . . British Columbia has extended seed transfer zones 200 metres higher in elevation for most species, and introduced new policy to allow the planting of western larch outside of its previous range. Alberta has extended seed transfer zones 200 metres higher in elevation and 2 degrees of latitude northward for most species. And Quebec has incorporated the risk of climate change maladaptation into seed transfer functions, planting seed mixtures composed of local and more southern seed sources in some regions.


  • Assisted population migration: The human-assisted movement of populations within a species' established range. (lower risk)
  • Assisted range expansion: The human-assisted movement of species to areas just outside their established range, facilitating or mimicking natural range expansion (intermediate risk)
  • Assisted long-distance migration: The human-assisted movement of species to areas far outside their established range, beyond areas accessible through natural dispersal. (higher risk)
  • Canadian Forest Service Publications:
  • Placing forestry in the assisted migration debate 2012
  • Why we disagree about assisted migration: ethical implications and the future of Canada's forest 2011
  • Assisted migration: Introduction to a multifaceted concept 2011
  • Assisted Migration to Address Climate Change in British Columbia: Recommendations for Interim Seed Transfer Standards" 2008
  • The implementation of assisted migration in Canadian forests 2011
  • Review of science-based assessments of species vulnerability: contributions to decision-making for assisted migration 2011.
    EXCERPT: "Recently, many tools have been developed for assessing species-specific vulnerability to climate change. These tools are question-based assessments that consider multiple criteria for individual species; the criteria are related to exposure and sensitivity to climate change. The following tools are discussed in relation to their use in Canada: (1) the NatureServe Climate Change Vulnerability Index; (2) the System for Assessing Vulnerability of Species to Climate Change (SAVS); (3) the Forest Tree Genetic Risk Assessment; (4) the Index for Predicting Tree Species Vulnerability; (5) ecological standards developed for the assisted migration for Torreya taxifolia; and (6) the Seeds of Success Program. These tools can all be applied to different forest species and they vary in such areas as their species-specific evaluation criteria, means for addressing uncertainty, and the integration of climate change models."

  • Potential Impacts of Climate Change on the Distribution of North American Trees - Daniel W. McKenney et al., BioScience, December 2007. Excerpt: "The mean centers of future climate envelopes are predicted to shift northward by 6.4 and 3.0 degrees latitude (i.e., roughly 700 km and 330 km) on average under the full-dispersal and no-dispersal scenarios, respectively (figure 2). The smaller northward shift shown by the no-dispersal scenario is not surprising given that, for this scenario, northward shifts are constrained by the northern edge of the current CE. However, the shifts predicted under the full-dispersal scenario are indeed drastic. The 25 tree species showing the greatest latitudinal shifts are listed in table 2. With the exception of white alder (Alnus rhombifolia), a western species, all of these species exhibit an extensive distribution in the southeastern quadrant of the continent, generally ranging north to the Great Lakes region. By the end of this century, the CE for most of these species is predicted to shift into northern Ontario and Quebec — in many cases to Hudson Bay. Results for the entire 130 tree species (and others) can be viewed at"

    BRITISH COLUMBIA : Re: "Assisted Migration Adaptation Trial (AMAT)" in British Columbia Content: "Can a tree native to coastal British Columbia, given climate change, flourish in Fort Nelson? Can a tree native to the Interior live prosperously on Vancouver Island? Those are questions Greg O'Neill hopes to find answers for. O'Neill is a geneticist with Vernon's Kalamalka Forestry Centre, and is overseeing forestry's biggest climate change research trial in North America." Note: O'Neill and other foresters in British Columbia may be the furthest along of anyone in terms of already doing assisted migration of plants and on a massive scale, though it is mostly at the level of reseeding logged lands with seedstock drawn from populations of the same species lower in altitude or latitude.
       What O'Neill and colleagues are doing in British Columbia can be learned in the most detail in this article published in the scientific journal Nature on 18 June 2009. You can access the PDF here: "Forestry: Planting the Forest of the Future". See also a transcript of a Canadian television documentary on O'Neil's work with assisted migration for British Columbia forest tree species. Also, O'Neill is a coauthor of the 2011 paper by Leech et al.: "Assisted Migration: Adapting Forest Management to a Changing Climate". See also the 2013 AMAT bulletin.
       Meanwhile, in the USA, a US Forest Service report, 2009 Science Accomplishments of the Pacific Northwest Research Station includes this: "To test the viability of assisted migration, researchers planted seedlings from locations throughout western Oregon and Washington and northern California at nine sites in western Oregon and Washington. Responses of the different seed sources will be evaluated relative to test site environments and the environments of the seed sources." Page 49 of Part 2 PDF
       Also see a cautionary comment published in BC Forest Professonal, which includes "Growing taller and being more resistant to two diseases in three years does not mean that one population is better adapted to an environment than another. What will happen during the rest of the cottonwood clones' lifetimes? There could be an unseasonal frost or a pathogen that is adapted to attacking mature black cottonwood, killing a large proportion of the assisted southern population, while these trees focus their energy budget on growth at the cost of decreased defenses." Also see 2009 "Climate change and Canada's forests: from impacts to adaptation".
       Also see, "Climate Change to Drive Lodgepole Pine Trees from British Columbia", 1 March 2011 Vancouver Sun; "Whitebark Pine (Pinus albicaulis) Assisted Migration Trial"; "Whitebark Pine Assisted Migration Trial at Blackcomb site in B.C."; "Assisted Migration for Larch" (see also a 2011 Discovery Magazine article on the larch project: "The Transplanted Forest: A Bold Experiment in Preemptive Climate Adaptation"; "Moving Trees Helps Prepare for Climate Change", Scientific American 24 August 2011; "Assisted Migration Vital, Researcher Says" (Sally Aitkin), 7 November 2012; "Assisted migration to address climate change: recommendations for aspen reforestation in western Canada" (L.K. Gray et al, in Ecological Applications, 2011).

    NOTE: A key, lengthy "discussion paper" was published in 2011 in the BC Journal of Ecosystems and Management: "Assisted Migration: Adapting forest management to a changing climate" by Leech, Almuedo, and O'Neill.

    ONTARIO: in May 2011, the Canadian province of Ontario published a detailed scholarly bibliography of papers pertaining to climatic needs and adaptability of FOREST TREES IN ONTARIO, CANADA. Downloadable in PDF, the title is: "Assessing assisted migration as a climate change adaptation strategy for Ontario's forests: Project overview and bibliography"; same reported updated in 2014. Note: In 2015 the owner of Haliburton Forest (a vast private forest in Ontario) announced of the native, more southerly species, black walnut "We think that might be one of the trees of the future," said Schleifenbaum. "The scientific term for what we are doing is called assisted migration."



        WESTERN USA: "Plant Species and Climate Profile Predictions". Highly detailed online maps to compare current, 2030, 2060, and 2090 range predictions for 76 species of western USA trees. (Always click on the .png versions to see the maps.) For example, Alligator Juniper, now absent from Colorado, is expected to have ideal range open up west of Denver in 2030, while southerly populations become stressed. (How are they going to get there, as the closest current population is near Santa Fe NM?) Note: A superb paper that details the data-source and modeling used to generate these range maps is "North American Vegetation Model for Land-Use Planning in a Changing Climate", 2012, G.E. Rehfeldt et al.

        EASTERN USA: Easy-to-use USFS webpage of maps imaging current and climate-shifted ranges of 134 tree species in eastern North America: Climate Change Tree Atlas interactive site. See also a multi-agency generated Forecasts Maps Projects for the Eastern USA. Note a terrific review chapter ("Climate Change and Forest Herbs of Temperate Deciduous Forests (TDF)" (USA) by Jesse Bellemare and David Moeller offers a cautionary perspective that the baseline presence/absence data used to construct climate envelopes and apply those to future climate predictions geographically may be flawed in that species with seed dispersal constraints may already be lagging in post-glacial habitat recovery, and thus "because hotspots of endemism and diversity tend to be localized to southern states where TDF species survived climatic cooling in the past, their range may now be poorly positioned to withstand future climatic warming. . . Large-scale dispersal limitation may be a relatively common phenomenon among small-ranged TDF plants and, as a result, assisted colonization could be both a necessary and effective conservation strategy for some species."

        WHOLE USA: This forest tree website builds on the previous (above) two, while adding a new feature of color-coded images that show relative difficulties in moving/adapting of different geographic populations of each species. Access here: The ForeCASTS Project, subtitle: Forecasts of Climate-Associated Shifts in Tree Species.

       Climate Change Response Framework

    The Framework is a collaborative, cross-boundary approach among scientists, managers, and landowners to incorporate climate change considerations into natural resource management. It provides an integrated set of tools, partnerships, and actions to support climate-informed conservation and forest management.

    Six Framework projects (see map left) encompass 19 states in the eastern USA, including 14 National Forests and millions of acres of forestland. Each regional project interweaves four components: science and management partnerships, vulnerability assessments, adaptation resources, and demonstration projects. Learn more about how the components interact to build a flexible, scalable, and effective strategy.

  • U.S. FOREST SERVICE: A 2009 article, "Genetic Options for Adapting Forests to Climate Change", by Brad St. Clare and Glenn Howe (USFS), published in the Jan/Feb 2009 issue of Western Forester. Michelle Nijhuis posted a review article in Nature (Sept 19, 2012) about southwestern USA massive forest fires leading toward replacement of conifer trees by more drought-adapted shrubs and scrub oak — and how some forest managers already are replanting with lower-elevation and warm-adapted species as a "bridge to the future.": "Forest Fires: Burn Out". NOTE: 21 February 2013 the "Western Forestry and Conservation Association" held a conference entirely on "Assisted Migration: A Primer for Reforestation and Restoration Decision Makers". Also see 2012 "Determining suitable locations for seed transfer under climate change: a global quantitative method" - (excerpt) "Changing climate conditions will complicate efforts to match seed sources with the environments to which they are best adapted. Tree species distributions may have to shift to match new environmental conditions, potentially requiring the establishment of some species entirely outside of their current distributions to thrive. Even within the portions of tree species ranges that remain generally suitable for the species, local populations may not be well-adapted to altered local conditions." USFS OVERVIEW DOCUMENT 2013: "POLICY AND STRATEGY CONSIDERATIONS FOR ASSISTED MIGRATION ON USDA FOREST SERVICE LANDS".

  • ROCKY MOUNTAINS USA: 2014 has a trilogy of papers published in Forest Ecology and Management, Rehfeldt et al., "Comparative genetic responses to climate in the varieties of Pinus ponderosa and Pseudotsuga menziesii" (Ponderosa Pine and Douglas Fir). Part III, Reforestation of Ponderosa Pine and Douglas Fir in the Rocky Mountain States (owing to the anticipated climate-induced vast die-off) is a detailed assessment of how anticipated climate change will necessitate not only the expansion of the ranges of both species northward but, owing to existing physiological distinctions within populations of these wide-ranging species, forest managers will need to assist northward movement of seeds in all parts of the range in order to ensure adequate genetics of physiology to meet the shifted climate zones. Note: Ponderosa Pine and Douglas Fir are dominant trees in Rocky Mountain forests; their anticipated weakening or outright extirpation owing to climate change by 2060 will be catastrophic both for ecosystem services and timber resources. In the authors' own words,
    "The potential impacts of Table 1 range from pronounced to dire. . . The conclusion seems inescapable that strategic adjustments of forest management and conservation practices are both urgent and inevitable. We advocate a robust artificial regeneration program as the single most important management tool for mitigating ecological impacts from climate change. This makes us ripe for criticism from those who object to 'assisted migration' largely because of the demonstrated abilities of humans to create ecological havoc, centered primarily on the concept of invasiveness (see Mueller and Hellman 2008). Yet careful analyses repeatedly have led to the conclusion that projected rates of climate change are faster than rates of response in natural systems. As a result, adaptation and migration lags are to be expected, leading, in turn, to the impoverished flora and loss of biodiversity evidenced in the climate change impacts recorded in packrat middens. . . For humans, the choice between action and inaction becomes an exercise in risk assessment. In our view, management objectives solely dependent on natural processes will be hopelessly ineffectual for supplying the amenities that humans expect from natural ecosystems within acceptable time frames. As indicated clearly by this series, perceived risks of inaction greatly outweigh the risks of action." (page 9)
       "Rocky Mountain Forests at Risk"

    September 2014

    by the Union of Concerned Scientists and the Rocky Mountain Climate Organization

    Although "assisted migration" is never mentioned in this 54-page report (freely available online in pdf), this is the ideal background document for the interested public (as well as forestry professionals) to read in order to grasp the extent and degree of dire climatic dieback of dominant species of Rocky Mountain trees — already underway.

  • MINNESOTA: Begin with these three online resources:
    2015: "A forest dilemma: What will grow in a changing climate?" - a brief news article that shows the agency controversies within Minnesota between those now experimenting on a large-scale with long-distant assisted migration and those who disapprove of planting more southerly species in Minnesota's northern forests.

    2010: "Trees Fit for the Future" by Gustave Axelson, in Minnesota Conservation Volunteer. Excerpt: "In Minnesota Frelich says forest managers should consider assisted migration of eastern hemlock trees from an isolated remnant stand near Duluth to areas along the North Shore. He says hemlocks could replace boreal conifers lost in a warmer climate."

    2009: "Wilderness Conservation in an Era of Global Warming and Invasive Species: a Case Study from Minnesota's Boundary Waters Canoe Area Wilderness" by Lee Frelich and Peter Reich, in Natural Areas Journal. This paper superbly explains a wide range of factors in the controversy over assisted migration (a.k.a. "facilitated migration" or "facilitation forestry"), including a distinction between "local assisted migration" (moving genotypes of local trees to north slopes and moister habitats to serve as micro-refugia) and "long-distance assisted migration", such as the eastern hemlock approach suggested in the Axelson article above.

    Then consult: THE NATURE CONSERVANCY "Climate Change Adaptation Case Study: Updating Northeast Minnesota's Forest Management Strategies" (2011) Excerpt: "Recent research findings from The Nature Conservancy in Minnesota and University of Wisconsin- Madison (Ravenscroft et al. 2010) show that forest composition in Northeast Minnesota is projected to change in the next 200 years. Loss in overall forest complexity and an increase in maple species are dominant characteristics of this projected change. Findings also show that over the long term, climate change may be working in direct opposition to current ('climate-uninformed') restoration management actions. Forest management in Minnesota has been focused on restoring boreal species. Recent research suggests that these same species are also unlikely to survive in a changed climate. A new, 'climate smart' strategy will manage for a larger diversity of tree species, allowing opportunity for the best-suited species to thrive under changed climate conditions and thus sustain an adapted future forest. . . . As noted by Miller and Woolfenden (1999) over a decade ago, the work in Ravenscroft et al. (2010) demonstrates that rapid climate change poses serious questions to the practice of using historical data to develop management plans when we know that future climates will significantly differ from past climates. These results suggest that new approaches to forest management, that facilitate adaptation to new climates, may be needed to maintain functional forest ecosystems."
         Note: See a superb, long popular article on this assisted migration action in a 2013 issue of the Minneapolis Star Tribune: "Saving the Great North Woods". Excerpt: "Driven by a warming climate, scientists predict, the [boreal forest in NE Minnesota] will soon follow the glaciers and retreat north by as much as 300 miles in the next century. Much of northern Minnesota, they say, will become open savannas like those in Nebraska and eastern Kansas — with grasses and brush, a few scattered trees, and domes of bare rock rising from the ground.
         The Nature Conservancy is a participant in The Great North Woods climate adaptation work: "Adaptation Forestry in Minnesota's North Woods". Excerpt: "In the Great Lakes region, conventional forestry practices currently emphasize the regeneration of aspen-birch forests. Today's forestry techniques, such as clear-cutting and planting white spruce or red pine, are likely to become commercially and ecologically unviable as many northern tree species decline under anticipated warmer, drier conditions. . . Our suite of climate-adapted tree species includes bur oak, red oak, white pine, and basswood. We chose these species because ecological modeling suggests they are likely to thrive under warmer, drier conditions. All four species are native to the region, but uncommon due to a legacy of past harvesting practices, a climate that historically favored boreal species and dispersal limitations." See also a 3 September 2014 news report on this project: "Moving a Forest: as climate changes, ecosystems will need to shift".

       "Minnesota Forest Ecosystem Vulnerability Assessment and Synthesis: A Report from the Northwoods Climate Change Response Framework Project"

    May 2014 by U.S. Forest Service

    Although "assisted migration" is rarely mentioned in this report, the need for it is evident, particularly in the description of how the species mix is expected to shift:

  • Boreal species such as quaking aspen, paper birch, tamarack, and black spruce are projected to decrease in suitable habitat and biomass across the assessment area.

  • Species with ranges that extend to the south such as American basswood, black cherry, northern red oak, and eastern white pine may increase in suitable habitat and biomass across the assessment area.
  • N WISCONSIN: A multi-author paper published 2014 in the Journal of Forestry is "A Practical Approach for Translating Climate Change Adaptation Principles into Management Actions". One of the case studies is a Nature Conservancy project in northern Wisconsin. Assisted migration is mentioned in this way:
    ". . . Swamp white oak (Quercus bicolor) and bur oak (Quercus macrocarpa) were identified as two potential species that could be planted in lowland hardwood forests to maintain forest cover if intervention was deemed necessary. These species are not currently present on the property but can be found in localized areas in northern Wisconsin, which would represent a small degree of assisted migration."
    Table 3 in that paper lists tree species expected to experience a large decrease, those expected to increase, and those not currently in northern Wisconsin but expect to be newly capable of thriving there. A partial list is:
    LARGE DECREASE expected: Balsam fir, Black and White Spruces, Eastern hemlock, Northern White Cedar, several species of birch, Quaking aspen. LARGE INCREASE expected: American Beech, Black Oak, Black Walnut, Black Willow, Bur Oak, Eastern Cottonwood, Eastern Red Cedar, Hackberry, Osage Orange, 4 species of Hickory, Silver Maple, Swamp White Oak, White Oak. NEW ENTRY opens up (the implication being that assisted migration will be necessary to bring the trees north): Chestnut and Chinkapin and Shingle oaks, Persimmon, Redbud, Dogwood, Honey locust, Ohio Buckeye, Pecan, Pin and Post and Scarlet oak, Red mulberry, Sassafras, River birch, Sycamore, Wild plum, Tuliptree.
    The paper concludes, in part:
    "Although adaptation inherently spans the boundary between the research and management communities, the current conversation within the forestry community is still largely centered on understanding the potential impacts of climate change on forests. In our opinion, this limited view is inadequate, as the complexity and increasing urgency of the issue as well as the need for place-based decisions require active engagement from forest managers and other natural resource professionals."

  • N WISCONSIN & MICHIGAN: A 249-page 2014 USDA report (freely available in pdf) is a must-read for all those interested in adapting Great Lakes area northern forests (zone marked above blue line, below left) in this century of rapid climate change:
       "Forest Ecosystem Vulnerability Assessment and Synthesis for Northern Wisconsin and Western Upper Michigan: A Report from the Northwoods Climate Change Response Framework Project". Although "assisted migration" is only slighted mentioned in this report, it will be apparent to all knowledgeable readers that such assistance will be vital in this region. Notably, the boreal tree species with their southern-most current ranges in this region will greatly diminish or entirely wink out, so more southerly species will need to be introduced to ensure multi-layer forest health. EXCERPT:
        "Many of the species projected to decline are boreal or northern species that are currently near the southern limit of their range in the assessment area, including black spruce, balsam fir, quaking aspen, paper birch, and white spruce. These species are currently very common across the landscape and play a dominant role in many forests, and the reduction of suitable habitat for these species may affect a large portion of northern Wisconsin and the western Upper Peninsula." (p.92)

    EXCERPT (of above report): "Suitable habitat will be available in the future under at least one of the climate scenarios for 26 species that are not currently present in the assessment area. This projection does not necessarily mean that a given species will be able to migrate to newly available habitat and colonize successfully, but rather that conditions may be suitable for a species to occupy the site if it is established. Many species that are not currently present in the assessment area would require long-distance migration, whether intentional or unintentional, in order to establish and occupy suitable habitat in the assessment area. Habitat fragmentation and the limited dispersal ability of seeds could also hinder the northward movement of the more southerly species, despite the increase in habitat suitability (Ibanez et al. 200). Further, species are generally expected to migrate more slowly than their habitats will shift (Iverson et al. 2004a, 2004b). Of course, human-assisted migration is a possibility for some species and may be tested and used over the coming decades (Pedlar et al. 2012)." (p. 93)

    A similar report to the above, also published by the USDA (USFS) in 2014, focuses exclusively on the "Mixed Laurentian Forest of MICHIGAN" (pictured in green in the image left). The 230-page report is freely available in pdf: "Michigan Forest Ecosystem Vulnerability Assessment and Synthesis: A Report from the Northwoods Climate Change Response Framework Project"

    Report excerpt at right:

       "Black spruce and white spruce are projected to have the most dramatic reductions in suitable habitat. Balsam fir, black ash, paper birch, and tamarack also have low modifying factor scores, suggesting that there are life-history traits or biological stressors that may cause these species to lose even more suitable habitat than the model results indicate." (p. 89)

    "17 species not already present will gain new suitable habitat within the assessment area by the end of the 1st century. A given species will not necessarily be able to migrate to newly available habitat and colonize successfully, however. Species not currently present in the assessment area would require long-distance migration, whether intentional or unintentional, to occupy suitable habitat in the assessment area. Because the Great Lakes and the Straits of Mackinac present substantial barriers to migration, southern species may be even less able to occupy suitable habitat in the eastern Upper Peninsula. Habitat fragmentation and the limited dispersal ability of seeds could also hinder the northward movement of the more southerly species, despite the increase in habitat suitability. Most species can be expected to migrate more slowly than their habitats will shift. Of course, human-assisted migration is a possibility for some species and is expected to become tested and used during the next decades."(p. 90)

  • PENNSYLVANIA: "Climate change to Philly trees: It's not 1910 anymore" (news article) by Carolyn Beeler, 23 January 2015. Surveys Philadelphia and Chicago urban trees and parks managers who have already begun planting more southerly tree species on municipal lands. Joan Blaustein, head of urban forestry and ecosystem management at the Philadelphia Parks Department, is quoted: "We need to anticipate what the conditions are going to be 100 years from now, rather than trying to restore to 100 years ago." Beeler writes, "In the fall, the city will plant non-native trees suited to warmer climates, including the Southern chestnut oak and bald cypress, and plant some species native to Pennsylvania that are currently at the northern end of their range, such as the Southern red oak and red mulberry. . . In five years, Blaustein hopes the early results of her experimental test plots will give her an idea of which new trees to plant city-wide."

  • MAPLE TREES: March 2012 news article: "Climate change could wreak havoc on maple syrup industry". Excerpt: "According to The Maple Daily, a news site dedicated to maple syrup, sugar maple trees now release their sap about 8.2 days earlier in the year and stop producing it 11.4 days earlier, resulting in a total of about 10 per cent loss in the duration of the maple production season . . . There is currently a debate as to whether forestry experts should be stepping in and taking action in the form of something like an assisted migration, moving trees to a more northern climate to protect them in a careful and controlled way, but like many other aspects of the industry, there is a lot of uncertainty."

  • SUGAR MAPLE in Great Lakes states: 2014 USDA report: "Forest Ecosystem Vulnerability Assessment and Synthesis for Northern Wisconsin and Western Upper Michigan: A Report from the Northwoods Climate Change Response Framework Project". EXCERPT:
    Box 11 (p. 115): Hardwood Decline in the Upper Great Lakes Region: Northern hardwood stands with sugar maple crown dieback have recently been reported in the upper Great Lakes region. Permanent plots have been established on industrial, Federal, and State land in the Upper Peninsula of Michigan, northern Wisconsin, and eastern Minnesota in order to investigate the cause of this dieback. Mean sugar maple crown dieback percentage of live trees at all plots varied from 15 percent in 2009 to approximately 7 percent in 2012. Healthy sugar maple stands typically have less than 10-percent dieback. Analysis has indicated that sugar maple dieback is related to many factors, including exotic earthworms, climate, and soil nutrient variability.
        Out of all plot variables measured, the forest floor condition was the significant factor related to mean sugar maple crown dieback (2009-12). The removal of the duff layer by high densities of European earthworms exposes roots, disturbs biogeochemical cycling, reduces soil moisture, increases soil temperature, affects mycorrhizal communities, and generally exacerbates further stresses on trees. Evaluation of basal area growth indicates a significant positive relationship with total winter snowfall, number of days with snowcover on the ground, and number of days below freezing temperatures across the region, all of which have been decreasing in recent decades. Tree roots of sugar maple and other northern hardwoods are generally frost intolerant, and lack of adequate snowcover exposes these shallow roots to freezing conditions. Moderate drought conditions in recent years, especially in the Upper Peninsula of Michigan, have likely further contributed to maple dieback (Bal 2013). The presence of earthworms and poor soil fertility are also likely contributing to poor crown conditions and decline in many areas.

       USDA regional report 2014:

  • "Central Hardwoods Ecosystem Vulnerability Assessment and Synthesis: A Report from the Central Hardwoods Climate Change Response Framework Project"

    This assessment evaluates the vulnerability of terrestrial ecosystems in the Central Hardwoods Region of Illinois, Indiana, and Missouri to a range of future climates.

    Species predicted to DECREASE: Sugar maple, American beech, White Ash, Shortleaf Pine, Post Oak, Blackjack Oak.

    INCREASE: "Habitat will become more suitable for southern species. . . A major transition in forest composition is not expected to occur in the coming decades." Editor's note: >Global warming is expected to occur with strong latitudinal differences: more southerly latitudes will experience the least warming; more northerly, the greatest.

  • WESTERN LARCH: A 2010 article by Rehfeldt and Jaquish titled "Ecological Impacts and Management Strategies for Western Larch in the Face of Climate-Change". EXCERPTS: "much of the future distribution of climates suitable for western larch would be on lands currently not inhabited by the species today. . . Because western larch rotations usually are longer than 50 years, these maps suggest that the speed of climate-change may force managers to compromise growth and adaptedness in the short term in order to secure survival over the long term. . . Climate change will disrupt the adaptedness of populations and ultimately force the realignment of species distributions. . . . Bioclimate models for western larch can be used in conjunction with modeled geographic patterns of genetic variation to develop and map for the contemporary climate the seed zones and seed transfer guidelines needed for reforestation. . . Our figures demonstrate unequivocally that climatic ecotypes transcend political boundaries. Consequently, programs involving seed procurement and deployment, tree breeding and maintenance of breeding populations, and accrual of genetic gains in commercially important traits will be most efficient through transboundary cooperation. Threatened populations in particular may require conservation plantings in ex situ reserves outside political jurisdictions where future climates are amenable to the species."

  • ENGELMANN SPRUCE: "Interspecific and Intraspecific Variation in Picea engelmannii and its Congeneric Cohorts: Biosystematics, Genecology, and Climate Change" by G. E. Rehfeldt, 2004, USDA Report RMRS-GTR-134. EXCERPT from the "Global Warming" section on p. 16: "Immigration opportunities for taxa of the P. engelmannii complex are limited largely because taxa of the complex currently inhabit the high elevations. In the north, moreover, the distribution of the complex abuts and intermixes with that of P. glauca. While the P. engelmannii complex is montane, P. glauca is a component of the boreal forests distributed across the continental climates of the northern latitudes. These continental climates are warmer in the summer than the montane climates inhabited by taxa of the P. engelmannii complex. Climate data, for instance, show that habitats occupied by P. glauca range up to 2,100 degree-days greater than 5 degrees C and 21 degrees C for mean temperature in the warmest month, while maximums for the same variables in the P. engelmannii complex are 1,700 degree-days and 18 degrees C, respectively. A warming climate in the north, therefore, should further increase the inhospitality of the contemporary boreal forests to taxa of the P. engelmannii complex."
        "Extirpation and immigration notwithstanding, a portion of the region currently inhabited by taxa of the P. engelmannii complex should remain suitable for taxa of the complex throughout the century. Table 6 shows clearly, however, that those genotypes expected to be the best suited for the novel climates may today exist at large distances from the site of their future climatic optima. This means that accommodation of a warming climate by taxa of the P. engelmannii complex will not only involve extirpation and immigration, but also should result in a complete redistribution of genotypes across the landscape."
        Editor's note: In 2014 I created a 4-minute video of the devastation of Engelmann Spruce on Wolf Creek Pass (Colorado), set to music; watch it and weep. Go to the last four minutes of this hour-long video: "Climate, Trees, and Legacy 05 - Rocky Mountain Trees in Climate Peril".

  • YELLOW CEDARS IN COASTAL ALASKA: USFS Assisted migration underway! February 2012 news article: "Death of Yellow Cedars Linked to Climate Change". Excerpt: "For more than a century, yellow cedars in Alaska and British Columbia have been dying, yet it was recently confirmed by U.S. Forest Service researchers that the cause was due to climate change. With climate change, there has been less snow on the ground to insulate the shallow roots from extreme temperatures. And with less snow on the ground, frozen roots have led to the decline of 60 to 70 percent of trees covering 600,000 acres in Alaska and British Columbia. Researchers also believe that yellow cedars may thrive in areas outside of where it has already migrated, leading to the hope that assisted migration may restore the dwindling population of these trees. However, there is also concern that assisted migration may cause yellow cedars to become an invasive species. Nevertheless, a trial planting of yellow cedars in Yakutat has been successful with a first-year survival rate of more than 90 percent." The US Forest Service reports a, 2009 "facilitated migration" of Yellow Cedar to Yakutat (where it does not exist in the wild) from native range in Hoonah.
        2012 USFS report identifies paleo-refugia of Alaska Yellow Cedar, in "Shifting Climate, Altered Niche, and a Dynamic Conservation Strategy for Yellow-Cedar in the North Pacific Coastal Rainforest", by Paul E. Hennon et al.
    EXCERPT: What change in the environment triggered tree death in previously healthy forests? A chronology of the natural his- tory of yellow-cedar helps put forest decline into temporal context. The location of Pleistocene refugia (Carrara et al. 2007) aligns with the current distribution of yellow-cedar in Alaska in a manner that indicates that existing yellow-cedar populations may have origins in these refugia. An ongoing population-genetics study will address this hypothesis for yellow-cedar. Climate reconstruction through pollen analysis suggests that only in the late Holocene has coastal Alaska experienced the cool, wet climate that led to the extensive peatland vegetation (Heusser 1960) favorable for yellow-cedar expansion — the same soil conditions that subsequently became a long-term predisposing factor in forest decline (figure 3). At one location near Petersburg, Alaska, cedar pollen became abundant about 2200 years ago (Ager et al. 2010). The Little Ice Age (c. 1200-1900 CE) was a period when the majority of the glaciers in coastal Alaska reached their maximum extensions since the end of the Pleistocene (Calkin et al. 2000), but it is not known whether these glacier advances were driven by colder temperatures or by more snowfall. The ages of mature yellow-cedar trees, whether they are dead or still living, indicate that most of them regenerated and grew to their canopy status in existing forests during the Little Ice Age (Hennon and Shaw 1994, Beier et al. 2008). We hypothesize that this favorable climate allowed yellow-cedar to regenerate prolifically — in part, because snow keeps populations of Sitka black-tailed deer (Odocoileus hemionus sitkensis) in check (White et al. 2009) and because deer are major herbivores of cedar seedlings. It was during the Little Ice Age that yellow-cedar became more abundant at lower elevations, where it would later be most vulnerable to decline. The onset of yellow-cedar decline coincided with the end of the Little Ice Age (Hennon et al. 1990c), which would be consistent with reduced snow's being the environmental change that triggered widespread yellow-cedar tree death. A large pulse of yellow-cedar mortality occurred in the 1970s and 1980s (Hennon and Shaw 1994) during a notably warm period of the Pacific Decadal Oscillation (Mantua 2011).
        A conservation strategy for a climate-sensitive species needs to consider the manner in which past, current, and future climates affect the various ecological traits and life stages of that species. Because climate changes through time, the adaptive range of species becomes a moving target, and a conservation strategy must be dynamic. Climate is expected to impact each tree species in a unique manner; therefore, there is a need to model each species individually (Iverson et al. 2008).
        Our conceptual approach is to integrate snow cover and drainage in order to identify unsuitable, suitable, and potential new habitats for yellow-cedar. Specifically, we nested soil drainage within favorable climate envelopes, with an emphasis on adequate snow-cover levels, to define habitat suitability as the foundation for a conservation and management strategy for yellow-cedar (figure 7).
        One species that might substitute for yellow-cedar in the maladapted zone is western red-cedar (Thuja plicata [Donn ex D. Don]), which grows in some of the declining yellow-cedar forests at lower elevations in Alaska and British Columbia, south of latitude 57 degrees N. Western redcedar is a calcium-accumulating, decay-resistant, long-lived tree of commercial value that is prized by the local indigenous people. Its bark and wood properties, including wood chemistry, differ from yellow-cedar's, but the two trees have some ecological redundancy and offer similar ecosystem services. The northern range extent and elevational limit of western redcedar suggest that future warmer climate conditions will favor this tree in Alaska, which also appears to be the case in coastal British Columbia (Hamann and Wang 2006). More knowledge is needed on redcedar's adaptation to the same freezing injury that afflicts yellow-cedar before intensive efforts of promoting redcedar in declining forests would be justified (Schaberg et al. 2011).
        When favorable climate develops beyond its existing range, yellow-cedar may be particularly slow to migrate because of its low reproductive capacity (Harris 1990). The previously mentioned genetic study is designed to test the Holocene migration of yellow-cedar, which we suspect is slow and still proceeding toward the northeast. Yellow-cedar is absent from much of the widespread forested wetland in these areas, even though the conditions appear to be favorable for yellow-cedar and may have been so for thousands of years. Yellow-cedar may benefit from some assistance in migration to speed the colonization of new habitats as the climate warms.
        Assisted (or facilitated) migration is the deliberate movement by humans of genotypes and species into areas in which the projected climate is believed to be associated with high probabilities of persistence. These activities can be controversial, because widespread movements of species can be interpreted as fostering the introduction of invasive species that could bring unanticipated consequences. Assisted migration may be required for species with narrow resource requirements or poor dispersal ability (Warren et al. 2001), such as yellow-cedar. As a cautious step, we conducted a trial planting of yellow-cedar near Yakutat, Alaska, (an area of discontinuous occurrence for yellow-cedar but still within its range limits; Hennon and Trummer 2001) to test the survival and growth of yellow-cedar where it did not previously grow. The first-year survival rate was over 90%, which suggests that the targeted expansion of yellow-cedar is possible.

  • NON-NATIVE LODGEPOLE PINE PLANTED ON KENAI PENINSULA (ALASKA) TO REPLACE NATIVE SPRUCE DEVASTATION BY CLIMATE-CAUSED SPRUCE BEETLE ERUPTION: Although not called "assisted migration", this intentional use of a more warm-adapted tree species (native to the dry northern Rocky Mountains, occurring naturally at lower elevations to the spruce zones on mountain slopes) is a clear example of foresters drawing upon a more southerly species native to the continent to replace forest dominants that are no longer viable, given the climate shifts already impacting Alaska. See: "Alaska: Across the Wildest State, Climate Change Threatens Many Species and Habitats", USF&WS June 2011.

  • REDWOOD TREES NORTH TO OREGON - David Milarch has been collecting branchlets from some of the "champion" trees of various species, especially in the USA. Because redwoods resprout from the base for many decades after the trunk is cut, he has collected clones of some of the biggest (long cut) specimens of historic times — and he is planning now to plant some of those clones "in areas that might be safer for the trees if the globe heats up, a process known as assisted migration." This was reported in The Oregonian ,"Ancient redwoods, giant sequoias to be 'archived' on Oregon coast", 27 Nov 2012.

  • ARIZONA CYPRESS Cupressus arizonica glabra, currently south of the Grand Canyon, needs to leap the Grand Canyon by 2030 - Warwell, Rehfeldt, and Crookston 2012 conclude: "In response to global warming under the IS92a scenario, the realized climatic niche space of Arizona smooth cypress should shift about 200 to 350 km northwest of its contemporary location (Figures 3B, 3C, 3D). The area occupied should increase by about 1.5 and 2 times its contemporary size in decades 2030 and 2060, respectively (Table 4). In decade 2090, the area decreases to 1.2 times the contemporary size as the distribution shifts to northern Nevada and southwestern Colorado. In all three future decades, the contemporary realized climatic niche space is expected to be prominent in valleys where the Arizona, Nevada, and Utah borders meet. This includes the Virgin Mountains in Nevada, an area where naturalized populations of the subspecies have been observed (Charlet 1996)."
        Meanwhile the subspecies currently east of Bakersfield CA will no longer survive in its current habitat by 2060: "By decade 2030, the Paiute cypress realized climatic niche space will lie outside its contemporary distribution. By 2060, the realized climatic niche space of this subspecies occurs exclusively in Oregon."
        Note: The importance of maintaining the genetic diversity within the Arizona Cypress complex during climate change is grounded in this 1997 background document: "Quantitative Analyses of the Genetic Structure of Closely Related Conifers with Disparate Distributions and Demographics: The Cupressus Arizonica Complex", by Gerald E. Rehfeldt. He concludes that: "perpetuation undoubtedly will require human intervention, particularly in the face of rapid climate shifts (see Wigley and Raper, 1992). The two primary human roles most likely will be to assist migration by maintaining the appropriate habitat and providing the genotypes appropriate to those habitats."

  • WHITE PINE IN EASTERN NORTH AMERICA - "Climatic niche, ecological genetics, and impact of climate change on eastern white pine (Pinus strobus): Guidelines for land managers", by Dennis G. Joyce and Gerald E. Rehfeldt, 2013, Forest Ecology and Management.
    EXCERPT: "The Intergovernmental Panel on Climate Change has presented unequivocal evidence that the climate is changing (IPCC, 2007). Over the last 30 years, the mean global temperature has increased by 0.6 degrees C. During this same time period, isotherms marking the average annual temperature have moved pole-ward about 160 km, and the inertia of the global climate system ensures an additional warming of 0.4 degrees C over the next two decades (IPCC, 2007). If greenhouse gas emissions continue at the current business-as-usual rates, the speed of isotherm movement will at least double in the latter half of the current century (Hansen, 2009)
        Over the 21st century, the magnitude of climate shifts is expected to exceed the ecological amplitude of many tree species, eventually leading to extirpation over substantial portions of contemporary ranges (Barns, 2009; Iverson et al., 2008; Kirschbaum and Fischlin, 1996).
        Especially at middle to northern latitudes, persistence of tree species is projected to be contingent, in large part, on colonizing emergent suitable habitat beyond the northern limits of contemporary distributions (Williamson et al., 2009). But, post-glacial migration rates of North American tree species (McLachlan and Clark, 2004; McLachlan et al., 2007) are a small fraction (less than 2%) of the rate climate gradients are shifting (Hansen, 2009). A seed-dispersal simulation model applied to five species of trees native to the eastern United States indicated that there is only a small probability of colonization at distances beyond 20 km (Iverson et al., 2008).
        The conclusion drawn by many authors is that many North American tree species will experience range contraction at the trailing southern edges with little prospect of effective stochastic range expansion to the north (Barns, 2009; Iverson and Prasad, 1998; Iverson et al., 2008; Keenan et al., 2011; Ledig et al., 2010; Rehfeldt, 2004; Rehfeldt and Jaquish, 2010; Thomas, 2004; Thuiller, 2003). In the face of these conclusions, forest managers are challenged to choose the most appropriate management options for maintaining and enhancing productive forests. Preparing to mitigate adaptational and dispersal lags through assisted redistribution of native tree species is fundamental component of this challenge (Ledig et al., 2010). While the challenge is clear, the task is daunting.
        Eastern white pine is one of the most commercially valuable trees in eastern North America. It is most abundant in a broad latitudinal band extending from northwest Ontario, Minnesota and Wisconsin eastward to the New England states and the Maritime Provinces (Iverson et al., 2008). The natural range also extends southward primarily along the Appalachian Mountains reaching its southern limits in Georgia. It occurs on nearly all soils within its range, but is most competitive on well drained sandy soils of low to medium site quality (Wendel and Smith, 1990).
        The entire southern half of the contemporary spatial and genetic distribution of P. strobus is projected to be extirpated by mid-century as habitat deteriorates. Where habitat remains suitable, the cumulative stresses of increasing maladaptation of endemic climatypes elevates both acute and chronic population susceptibility to insect and disease attack, and will likely lead to ineffective seed production. Under these projections, multiple-generation persistence of populations in the contemporary distribution will be the exception. And, projecting the emergence of suitable habitat in the future does not imply occupancy. Indeed, projected geographic shifts for P. strobus are at least two orders of magnitude greater than estimates of post-glacial dispersal rates in trees (McLachlan and Clark, 2004; McLachlan et al., 2007). The effectiveness of stochastic colonization is dubious, but extensive population decline and extirpation in the contemporary distribution is inevitable.
        Silviculture programs of the twenty first century are faced with the daunting tasks of conserving the existing resource in the short term by mitigating the elevated stress associated with climate warming and focusing reforestation on a redistribution of species and genotypes to the appropriate array of climates. (Rehfeldt et al., 2006). . . As the climate changes, populations such as the Virginia provenance may be suitable for transfer into Ontario to address adaptation concerns.
        The consistency of the projected redistribution for both the climate and ecological genetic profiles places Pinus strobus on a growing list of temperate and boreal tree species that appear to be poorly equipped to persist in their contemporary distribution as the climate warms. The magnitude and speed of climate change is projected to lead to widespread range recession; preclude requisite adaptation of populations in situ; and exceed the capacity of marginal populations to colonize increasingly disjunct emergent suitable habitat. It seems clear that maintaining optimal growth and productivity of P. strobus as the climate warms will require substantial artificial reforestation efforts focussed on matching climatypes to suitable habitat.

  • PINE TREES IN NEW JERSEY THREATENED BY NATIVE PINE BEETLE DUE TO WARMER WINTERS - "In New Jersey Pines, Trouble Arrives on Six Legs", 1 December 2013 report in New York Times. Excerpt: In an infestation that scientists say is almost certainly a consequence of global warming, the southern pine beetle is spreading through New Jersey's famous Pinelands. It tried to do so many times in the past, but bitterly cold winters would always kill it off. Now, scientists say, the winters are no longer cold enough. The tiny insect, firmly entrenched, has already killed tens of thousands of acres of pines, and it is marching northward. Scientists say it is a striking example of the way seemingly small climatic changes are disturbing the balance of nature. They see these changes as a warning of the costly impact that is likely to come with continued high emissions of greenhouse gases. The disturbances are also raising profound questions about how to respond. Old battles about whether to leave nature alone or to manage it are being rejoined as landscapes come under stress.

      LEFT: One of several images from "Recent declines of Populus tremuloides in North America linked to climate", 2013, James. J. Worrall et al., Forest Ecology and Management.

    Excerpts: "Because early, warm springs can advance phenology, climate change is expected to increase the exposure of trees to damage by spring frost. Indeed, aspen phenology in Alberta has advanced 2 weeks over the last 70 years, and exposure to spring frost has consequently increased. Thus, the large and damaging events in Arizona in 1999 and Utah in 2007 may become more common. Cycles of thawing and freezing during winter dormancy can injure plants in a variety of ways, generally referred to as winter injury. Warm periods deharden buds, twigs, cambium, sapwood, or roots, leaving them vulnerable to freezing temperatures that follow. Thaw-freeze cycles also cause winter cavitation of xylem vessels, to which aspen is relatively susceptible. Like spring frost, incidence of thaw-freeze events will likely increase with climate warming."

  • "ASPEN, Climate, and Sudden Decline in Western USA", G.E. Rehfeldt et al., 2009, Forest Ecology and Management.

  • "Potential colonization of newly available tree-species habitat under climate change: an analysis for five eastern US species", 2004, Iverson et al. Note: the 5 species are: persimmon, sourwood, sweet gum, loblolly pine, and southern red oak. EXCERPT: "By evaluating the probability of colonization within the potential 'new' suitable habitat, we can estimate the proportion of new habitat that might be colonized within a century. This proportion is low (<15%) for all five species, suggesting that there is a serious lag between the potential movement of suitable habitat and the potential for the species to migrate into the new habitat. However, humans could hasten the migration of certain species by physically moving the propagulesbeech, that have lost many of their animal dispersers."

  • "The Tree Coroners": To Save the West's Forests, Scientists Must First Learn How Trees Die" - in-depth article focusing on USA southwestern forest species stressed by heat and drought, by Cally Carswell, 9 December 2013, High Country News.

  • "Darcy's Law Predicts Widespread Forest Mortality Under Climate Warming" - by Nathan McDowell and Craig Allen, May 2015, Nature Climate Change. Excerpts: "Tall trees of old-growth forests are at the greatest risk of loss. . . Planting of southerly and low-elevation genotypes into more northerly or higher-elevation landscapes is another forward-looking adaptation approach to increase the resiliency of future forests to warming and extreme droughts."

  • "Assessing the potential for urban trees to facilitate forest tree migration in the eastern United States" by C.W. Woodall et al., 2010, Forestry Ecology and Management - helpful charts showing large urban areas of northeastern USA that have tree species in plentiful plantings north of their native range (e.g., Sweet Gum (Liquidambar) planted in New York City is 2 degrees latitude farther north; Southern Live Oak and Water Oak planted in Boston are 8 degrees and 5 degrees, respectively, farther north). Caveat: Ability of those individuals to actively move seed into surrounding wild forests is low; thus suburban plantings and outward plantings by landscapers will be more important to facilitate assisted migration in pace with climate change.

    OYAMEL FIR FOR MONARCH BUTTERFLIES IN MEXICO: - "Abies religiosa habitat prediction in climatic change scenarios and implications for monarch butterfly conservation in Mexico", 2012, Saenz-Romero et al., in Forest Ecology and Management CONCLUSION: "The predicted suitable climate niche for A. religiosa will diminish rapidly over the course of the century: a decrease of 69.2% by the decade surrounding 2030, 87.6% for that surrounding 2060, and 96.5% for 2090. To realign genotypes to the new locations of those climates for which they are adapted, the distribution of A. religiosa would need to shift upwards 300 m by 2030. The only feasible way for migration of this magnitude to be accomplished in such a short time is by the adoption of assisted management strategies. By the end of the century, suitable habitat for the monarch butterfly may no longer occur inside the Monarch Butterfly Biosphere Reserve. Research is needed on appropriate techniques for successfully transferring contemporary populations of A. religiosa to higher altitudes and poorer site conditions than those at which they cur- rently exist. Research is also needed on whether monarch butterfly migrating populations would overwinter on A. religiosa transferred to new sites or on other species transferred to sites currently inhabited by A. religiosa."
          For more on Mexican conifers, see "Altitudinal assisted migration of Mexican pines as an adaptation to climate change", by D. Castellanos-Acuna et al., 2015, Ecosphere.

    A GLOBAL PERSPECTIVE ON FORESTS: "The role of forest genetic resources in responding to biotic and abiotic factors in the context of anthropogenic climate change", R. Alfaro et al. (international co-authors), 2014, Forest Ecology and Management

    EXCERPTS: "Given the pivotal role of trees in ecosystem function, abrupt climate change impacts on them may thus have profound consequences for forests as a whole (Whitham et al., 2006). Irreversible loss of ecosystem integrity and function may follow, with replacement by new non-endemic ecosystems (Gunderson and Holling, 2002; Mooney et al., 2009).
        Assisted migration involves human movement of tree seed and seedlings from current locations to sites modelled to experience analogous environmental conditions in the future (Guariguata et al., 2008; McLachlan et al., 2007). Such movements may be latitudinal, longitudinal or altitudinal, and are designed to reduce extinction risks for those species not able to naturally migrate quickly enough, and to maintain forest productivity (Heller and Zavaleta, 2009; Marris, 2009; Millar et al., 2007). Assisted migration may be undertaken over long distances, or just beyond the current range limit of particular genotypes and populations, or within the existing range (Winder et al., 2011). A gradual form of assisted migration could consist of reforestation of harvested sites with seed from adjacent locations likely to be better adapted to the planting site under future climate (e.g., in the Northern hemisphere, using seed from sources to the south; in mountainous regions using seed from lower elevations).
        Another challenge to assisted migration that is specific to long-living perennials is that, where climate is changing quickly, large differences in conditions may be observed over an individual trees lifespan. To find species or genotypes well adapted to conditions at establishment and at productive maturity (e.g., for some species, perhaps a century later) may therefore be difficult. In order to achieve a proper balance, the interval to production/maturity needs to be considered, and multiple stepped translocations over time may be required (Soto-Correa et al., 2012). In addition, changes to pest outbreak risk could simultaneously occur as a result of climate change, and this should be factored into assisted migration decisions (Murdock et al., 2013).
         Another useful approach is to conduct assisted migration on assemblages of species with positive interactions that reduce climate risks. For example, a 'first-stage' species may be planted as a nurse crop to provide protection from temperature extremes for a second tree. Such an approach has been applied to Abies religiosa (Kunth) Schltdl. et Cham., using the leguminous shrub Lupinus elegans Kunth as a nurse plant for seedlings (Blanco-Garcia et al., 2011). Within species, assisted gene flow, where genes are exchanged between populations by moving individuals or gametes, has also the potential to control and reduce mal-adaptation (Aitken and Whitlock, 2013).
         Assisted migration responses to climate change that are based on greater dependency on the trans-national exchange of forest genetic resources require an appropriate policy and legislative environment to support transfer, including by the harmonisation of phytosanitary requirements, as noted by Koskela et al. (2009). At a national level, policies defining seed zones will need to be modified to allow the assisted migration of genetic material within nations. Countries developing national forestry action plans should also be encouraged to specifically include genetic level responses to climate change in their plans, which has sometimes, but not always, been the case to date (Hubert and Cottrell, 2007).
         As in previous climate change episodes, forest genetic resources will recombine to produce new variants, which through natural or assisted selection will produce the genotypes required to continue providing the ecosystem services that societies need from forests. But, as climate change progresses it will be important to monitor the adaptation of trees, stands and ecosystems, and to intervene with efforts to support adaptation where needed.


  • VIDEO: Climate Change Prompts Tree Deaths: Australia and the World (2012)

    11-minute video of 2012 produced by Australian television. Superb introduction to how increases in heat and drought contribute to tree deaths of an unprecedented scale. This video focuses on Australia, but also looks at the western USA, the Amazon forest, and elsewhere. The implications: Trees with slow natural rates of dispersal (anything other than wind-blown seeds) will require human-assisted migration of more heat-adapted populations of the same species or altogether different species.

  • VIDEO: Whitebark Pine Assisted Migration Trial in Canada & Alaska (2012)

    by Sally Aitken. Key topics include:

    26:52 - assisted migration section begins

    51:08 - the polarized debate on assisted migration

    56:03 - moving whitebark pine beyond its current range

    01:01:21 - risks of action v. inaction

    See also McLane and Aitken 2011, "Whitebark Pine Assisted Migration Trial", which says, "Whitebark pine will be extirpated from most of its current range over the next 70 years."

  • VIDEO: Greater Yellowstone Research: Whitebark Pine and Clark's Nutcracker Mutualism (2012)

    12-minute video of fieldwork by Taza Schaming, with excellent visuals of dead and dying Whitebark Pines and the key role played by Clark's Nutcracker in prying open the cones and then burying the seeds.

  • VIDEO: Whitebark Pine Ecology: Management of an Ecosystem in Decline (2012)

    38-minute video of 2012 illustrated talk by Dan Reinhart, ecologist of Yellowstone National Park. By clicking left, you will begin at 08:48 timecode, where the talk begins.

  • VIDEO: "Forest Trees in Climate Peril" - 45-min presentation by Connie Barlow to conservation audience in Prescott AZ, 2014.

  • VIDEO: "Climate, Trees, and Legacy" - a multi-lesson video series in 2014 exploring possibilities of assisted migration of North American trees on a species-by-species basis (Torrey Pine, Joshua Tree, Arizona Cypress, Alligator Juniper, Ponderosa Pine, etc.)

    ASSISTED MIGRATION: Misc. papers and articles

  • "Assisted Colonization: Moving Species for Conservation Purposes" undated website announcement of Conservation Breeding Specialist Group (CBSG), affiliated with the IUCN
    "IUCN has requested a review and update of its policies on this topic, with the aim of having a comprehensive IUCN position for submission at the 2012 World Conservation Congress. Accordingly the SSC has established the RSG-ISSG Task Force on Moving Species for Conservation Purposes. The lead person in this task force is Mark Stanley Price. Mark will convene a working group to discuss that scale, scope and terminology around this initiative and to gather answers to the questions: (1) How, where and for what do the benefits and risks of assisted colonization or conservation introduction compare favorably to doing nothing to assist species vulnerable to extinction? (2) What taxa of plants and animals do participants feel are the best bet for assisted colonization? and (3) What should be done to test some hypotheses?

  • "Relocating Animals to Safer Climes" journalist report by Reena Amos Syes, Emirates Business, 6 June 2010.
    Focal species is the reintroduction of extirpated Oryx to its homeland in Oman and how that will be affected soon by the scheduled release in 2012 of international guidelines for translocation of species in response to climate change by the "Species Survival Commission." Quotes fr Dr Mark Stanley Price, incl: ""That is why chosen scientists from all over the world have been asked by the International Union for the Conservation of Nature and Natural Resources (IUCN), to set up a group to look at assisted colonisation globally. It wants us to set up guidelines for assisted animal colonisation and release new guidelines at the World Conservation Congress in 2012 in South Korea."

  • Rare S. Appalachian plant being tested for assisted migration Smith College News, 26 July 2010.
    Excerpts: Last fall, Kaila Matatt '10 joined Jesse Bellemare, assistant professor of biological sciences, on a five-year investigation into the success of relocating one plant, the Umbrella Leaf, to cooler climes. The native of southern Appalachia met the typical criteria of plants that are most in danger of extinction — those with small geographic ranges and limited ability to disperse, she said. When Bellemare began the investigation in 2008, he sought and received approval to temporarily transplant the Umbrella Leaf to areas within state forests in Virginia, Maryland, Pennsylvania, New York and Massachusetts. He also identified three control sites within the native range to provide a comparison. Until the end of the project in 2013, the plants will continue to be monitored for germination and growth, as well as monitored for flowers and seeds, she said. After that, all of the transplants will be removed.

  • "Deciding when to move plants and animals to save them from global warming" journalist report by Cassandra Brooks, Stanford Report, 5 June 2009.
    Report of 25 May 2009 multi-author paper in Proceedings of the National Academy of Sciences, which proposes a new management tool for choosing which species are most viable for relocation based on a series of social and ecological criteria—for example, how much is known about the biology, geographical distribution and the ecological uniqueness of the species, as well as how easy they are to catch and move. Social factors, such as cultural importance, financial impact and even the laws and regulations regarding the species, also are considered. Partially funded by the National Science Foundation (NSF), the working group is co-led by Jessica Hellmann and Jason McLachlan of the University of Notre Dame, Dov Sax of Brown University, and Mark Schwartz of the University of California at Davis. David Richardson of Stellenbosch University in South Africa led the writing of the paper. See also this Press Release on the paper.

  • "Between the Devil and the Deep Blue Sea" science journalist article by Jim Robbins, Conservation, Apr-Jun 2009.
    Arresting article on the extent and speed of the paradigm shift in conservation away from traditional "preservation" modes of intervention in behalf of biodiversity to "adaptationist" modes, including the growing acceptance of "assisted migration" as a management tool to cope with globally and regionally shifting climates. Superb coverage of the wrenching change of heart (and financial focus) for conservation programs rooted in "restoration" to practically address the irreversible shifts in climate now inarguably underway. "Managed retreat" (term used by conservation biologist Reed Noss, who argues for an overhaul of Everglades restoration policy) now joins "assisted migration" in the growing panoply of conservation terms and tools.
    Note: Serious students of this topic may wish to start with the paper by Shirey and Lambert (below), as it is an excellent summary of the ecological science, the actions-to-date, the law, and the regulatory options, and it was clearly written from an objective position, neither pro nor con.

  • "Assisted Colonization Under the U.S. Endangered Species Act" by biologists Patrick D. Shirey and Gary A. Lamberti, in Conservation Letters, February 2010 3(1): 45-52 [full text in PDF online free access]
    "The paper represents a call to arms or a call to caution, depending on your perspective," says Gary Lamberti, the chair of the Department of Biological Sciences who is Shirey's advisor and co-author of the article. "When we're thinking about moving organisms around because of climate change or other environmental factors, we need to think about the legal framework that will enable or not enable us to do that. What Patrick did with his analysis was encourage policy makers and legal scholars to examine the statutes before we reach a crisis point." (quotation drawn from the author's online announcement of the paper). Here are several important legal conclusions made in the paper:
        "Current agency regulations impede alternative strategies such as assisted colonization for endangered animals, but do not impede assisted colonization of endangered plants." (p. 3) "On its surface, the statutory language of the ESA appears to provide the legal framework for allowing assisted colonization of endangered populations to new habitats primarily under Section 10(j), the experimental population provision" (p. 3) "In 1982 additions to the ESA, Congress sought to restrict the use of the experimental population provision as a means of removing protection from species and thus imposed procedural limits. Those limits, however, did not restrict the power of the agency to release species into suitable areas without considering historical distribution. The USFWS can authorize release outside the current range if 'release will further the conservation of such species' (citation). However, in promulgating regulations to implement the experimental population provisions, the USFWS added a geographic restriction in 1984 that prohibits an experimental population from being introduced outside the historic range, 'absent a finding. . . in the extreme case that the primary habitat of the species has been unsuitably and irreversibly altered or destroyed' (citation) (p. 5) "Perhaps the most successful case of assisted colonization of a plant listed under the ESA is the Virginia roundleaf birch (Betula uber). The first translocation of roundleaf birch occurred after the species was rediscovered in 1975 as a population of 41 trees (59 FR 59173). After the round-leaf birch was listed in 1978, the USFWS encouraged its distribution to conservation organizations and individuals (59 FR 59173). Despite protection of its habitat by agencies and landowners, the natural population of round-leaf birch declined to eight trees in 2003 ( However, because assisted colonization established 20 populations on U.S. Forest Service land, the USFWS reclassified roundleaf birch from endangered to threatened in 1994 (59 FR 59173)." (p. 6) "Regulatory restrictions placed on assisted colonization might be lesser obstacles to overcome than political and scientific resistance. Political opposition can include concern over costs of managing populations, resistance of landowners and local governments to introducing endangered species, and concern over species invasiveness. The threat of invasive species, in particular, raises legitimate scientific concern about assisted colonization." (p. 6) "Assisted colonization could be a viable management option to offset the human-caused and inseparable problems of habitat fragmentation and rapid climate change." (p. 7)

    To see what is going on in Europe on this topic, see pp 42-43 of Convention on the Conservation of European Wildlife and Natural Habitats: Standing Committee Report of November 2009.

  • "Anachronistic Fruits and the Ghosts Who Haunt Them", by Connie Barlow, 2001, in Arnoldia Magazine.
    Note: This article may be the first published advocacy of translocation (assisted migration) of Torreya taxifolia. The last section of the article is titled, "Is the Endangered Torreya Tree Anachronistic?". Barlow concludes, "Transplantation across great distances is an uncommon and controversial technique for biodiversity conservation today. But as the greenhouse effect ratchets up temperatures and reroutes rainfall, and as botanical preserves become even more isolated islands in a sea of human development, long-distance transplantation will become the norm. If gardening a few local patches of endangered plants is tough today, it's going to get a lot tougher when, like it or not, we become gardeners of the planet. Helping plants track climate change from one patch of habitat to another will be a routine tactic for conserving biodiversity decades hence. Is it too early to begin now with florida torreya?"

    VIDEO: First assisted migration action: Torreya

       Connie Barlow presents the rationale for advocating "assisted migration" northward to help an endangered conifer tree, Florida Torreya (Torreya taxifolia), recover from otherwise certain extinction. Barlow's talk was filmed in 2004 — the same year that she and Paul S. Martin co-authored an advocacy piece, "Bring Torreya Taxifolia North Now," published in Wild Earth magazine. 2004 was also the year that Connie coordinated the formation of and created a website for Torreya Guardians,

    Four years after this talk was filmed, Barlow and other Torreya Guardians" legally planted 31 nursery-grown seedlings of Torreya taxifolia in two forested plots of private land in the mountains of North Carolina. This action is recognized as the first intentional "assisted migration" for a plant species in the USA in direct response to climate change.

  • "Bring Torreya Taxifolia North — Now", by Connie Barlow and Paul S. Martin, 2004, in Wild Earth Magazine.
    Note: This paper is the first full advocacy of assisted migration for Torreya taxifolia. The authors conclude, "'Left behind in near time' may thus be a syndrome that applies to a number of extinct, imperiled, and soon-to-be imperiled plants, and perhaps to small, isolated populations of species that are not themselves in danger of extinction. How might this awareness alter our conservation options as climate shifts? By assisting the migration of Torreya taxifolia now, we can help to shape a better next chapter for this beleaguered tree and, perhaps, many other plants."

  • "NASA: Climate Change May Bring Big Ecosystem Changes", press release, December 2011, Jet Propulsion Laboratory.
    Excerpts: By 2100, global climate change will modify plant communities covering almost half of Earth's land surface and will drive the conversion of nearly 40 percent of land-based ecosystems from one major ecological community type . . . Most of Earth's land that is not covered by ice or desert is projected to undergo at least a 30 percent change in plant cover - changes that will require humans and animals to adapt and often relocate. . . While Earth's plants and animals have evolved to migrate in response to seasonal environmental changes and to even larger transitions, such as the end of the last ice age, they often are not equipped to keep up with the rapidity of modern climate changes that are currently taking place. Human activities, such as agriculture and urbanization, are increasingly destroying Earth's natural habitats, and frequently block plants and animals from successfully migrating.

  • "The Hidden Battle Behind Formal Gardens", report by Paddy Woodworth, 10 July 2010, in Irish Tmes
    Excerpt: Perhaps the most radical update on the table now is the concept of 'assisted migration', a benign phrase that just might be the key to keeping many trees, shrubs and flowers in the landscape — and out of the chilled filing cabinets. But it is a concept that also raises as many problems as it proposes to lay to rest. As with animals, plants migrate to find the best living conditions, but plants do it slowly, over generations. Trees, with their very long life spans, are especially slow. Earthworms are sprinters by comparison. Ten thousand years ago, as the ice sheets retreated from the North American Midwest, trees migrated up the continent at the rate of about 100km per century, until the global climate settled into relative stability — the condition we thought of as normal until very recently. Global change models suggest that climate 'envelopes' will soon be moving north at speeds of 1,000km per century. So, if the models are right, this is a race that trees are certain to lose. . . Donnelly knows that the best outcome of assisted migration will involve the disintegration of cherished and valuable communities of plants and animals. Whatever novel communities will emerge may be poorer, or even richer, in biodiversity than what we know today, but they will certainly be different. However, he argues soberly that assisted migration must be among our options for "managing long-lived trees for an uncertain future". Restoration used to be about attempting to return ecosystems to a past (and more biodiverse) state, but the wild card of climate-change is pushing restoration science towards the creation of new systems, with the proviso that maintaining biodiversity is still the target. EDITOR'S NOTE: A 2011 survey of the actual movement poleward or altitudinally by 1,376 species found that the average rate was 10 miles per decade poleward and 40 feet per decade upslope, but the individual variation was quite wide. See "Climate Change: Species Climbing Higher and Migrating North, Study Says".

  • "A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests", by Craig D. Allen and 19 other coauthors, 5 February 2010, in Forest Ecology and Management 259(4): 660-84.
    Excerpt from abstract: "Here we present the first global assessment of recent tree mortality attributed to drought and heat stress. Although episodic mortality occurs in the absence of climate change, studies compiled here suggest that at least some of the world's forested ecosystems already may be responding to climate change and raise concern that forests may become increasingly vulnerable to higher background tree mortality rates and die-off in response to future warming and drought, even in environments that are not normally considered water-limited. This further suggests risks to ecosystem services, including the loss of sequestered forest carbon and associated atmospheric feedbacks."

    For superb popular coverage of this article and the underlying forest-dieoff phenomenon, read the online report by Jim Robbins dated 15 March 2010: "What's Killing the Great Forests of the American West?".

  • "Naturalness and Beyond: Protected Area Stewardship in an Era of Global Environmental Change", by David N. Cole and 15 other coauthors, 2008, in The George Wright Society Forum 25:36-56.
    Highly useful integrative paper geared for managers of natural lands that examines the need for new philosophical and practical perspectives on management of parks and wilderness areas today, especially given rapid climate change. "Assisted migration" is discussed in this report, but in the much wider context, thus making this paper a key reading for background perspective as well as precise philosophical and management options that supplement the criterion of "natural" with more precise understandings of "historical fidelity," biodiversity conservation," "resilience," and "ecological integrity."

  • "Deep-Time Lags: Lessons from Pleistocene Ecology" by Connie Barlow, in Gaia in Turmoil: Climate Change Biodepletion, and Earth Ethics in an Age of Crisis, edited by Eileen Crist and H. Bruce Rinker, 2009, MIT Press.
    Torreya Guardians founder Connie Barlow contributed a chapter on the importance of a "deep time" perspective for conservation biologists and biodiversity activists coming to grips with the extinction crisis in an age of rapid climate change. The plight of Torreya taxifolia and the work of Torreya Guardians are used as the key example of "Assisted Migration in a Time of Global Warming".

  • "Paleoecology and 'inter-situ' restoration on Kauai, Hawaii" by David A. Burney and Lida Pigott Burney, in Front Ecol Environ 2007; 5(9): 483-490, doi 10.1890/070051.
    Review paper of ongoing work on Kauai that actively uses a pre-historic baseline (prior to first human arrival one- or two-thousand years ago) for developing standards for plant restoration ecology on the island. A great example that there is a continuum between "historic" and "Pleistocene" standards for "restoration" and "rewilding." A must-read for those who cling to "historic native range" standards for opposing on principle "assisted migration."

  • "Snakes Struggle to Keep Pace with Climate" news story in Futurity, (13 December 2011)
    Summary of PLoSOne paper, "Pleistocene Climate, Phylogeny, and Climate Envelope Models: An Integrative Approach to Better Understand Species' Response to Climate Change", by A. Michelle Lawing and P. David Polly, 12/2/11. Quotes from the news summary: "We find that, over the next 90 years, at best these species' ranges will change more than 100 times faster than they have during the past 320,000 years," says lead author Michelle Lawing, a doctoral candidate in geological sciences and biology at Indiana University. "This rate of change is unlike anything these species have experienced, probably since their formation." . . . Snakes won't be able to move fast enough to keep up with the change in suitable habitat, the study suggests. Creation of habitat corridors and managed relocation may be needed to preserve some species.

  • "A Home from Home: Saving Species from Climate Change" news story by Suzanne Goldenberg in, (12 February 2010)
    Conservation biologist Camille Parmeson is profiled in her advocacy for translocation of species threatened by climate change. She is quoted, "It doesn't make any sense to say it's OK for the shipping industry and the transport industry to accidentally move stuff around, for the aquarium trade to move stuff around, for the garden trade to move stuff all over the place, but that it's not OK for a conservation biologist who is desperately trying to save a species from extinction to move it 100 miles. Come on, we have mucked around with Earth to such a degree that I think it's a ridiculous argument.''

  • "Analysis of climate paths reveals potential limitations on species range shifts" by Regan Early and Dov Sax, Ecology Letters (29 September 2011)
    From press release: In a new study based on simulations examining species and their projected range, researchers at Brown University argue that whether an animal can make it to a final, climate-friendly destination isn't a simple matter of being able to travel a long way. It's the extent to which the creatures can withstand rapid fluctuations in climate along the way that will determine whether they complete the journey. Regan Early and Dov Sax examined the projected "climate paths" of 15 amphibians in the western United States to the year 2100. Using well-known climate forecasting models to extrapolate decades-long changes for specific locations, the researchers determined that more than half of the species would become extinct or endangered. The reason, they find, is that the climate undergoes swings in temperature that can trap species at different points in their travels.
        Confronted with these realities, Early and Sax say wildlife managers may need to entertain the idea of relocating species, an approach that is being hotly debated in conservation circles. "This study suggests that there are a lot of species that won't be able to take care of themselves," Sax said. "Ultimately, this work suggests that habitat corridors will be ineffective for many species and that we may instead need to consider using managed relocation more frequently than has been previously considered." news report on; illustrated report on.

  • "Taking Stock of the Assisted Migration Debate" by Nina Hewitt et al, Biological Conservation (volume 144, pages 2560-72), 2011.
    Lead author Dr. Nina Hewitt (a biogeographer and IRIS Senior Fellow) and her coauthors conducted a bibliometric study of the existing academic literature on assisted migration, classifying it in terms of study methods, geographic and taxonomic (species) focus, and degree of knowledge transfer from the natural sciences to other academic disciplines and non-academic sectors. They show that the volume of scholarly writing on assisted migration has exploded in the past three years, addressing a wide range of regions and species. The article's main contribution is to analyze the scholarly debate about the desirability and feasibility of assisted migration as a response to climate change. At a general level, a majority of the papers reviewed were generally supportive of using or at least considering assisted migration, but a closer examination shows that the debate is intensifying. NOTE: A news article on this report quotes Hewitt as saying, "With this paper, we were hoping to highlight the different sides of the debate so that scientists and policymakers can evaluate the risks and benefits and together make some progress so we don't get stuck in that paralysis. . . What I found was that the debate seemed to be stuck around what we call 'other issues' — neither direct risks nor benefits to implementing a particular assisted migration, but rather, counter arguments to the opposite side of the debate. These counter arguments need to be distinguished from direct risks and benefits because they can't provide justification for scrapping or adopting the policy."

  • "The assisted migration of western larch in British Columbia: A signal of institutional change in forestry in Canada? by Nicole L. Klenk and Brendon M.H. Larson, Global Environmental Change 2014.
    EXCERPTS: Based on 46 interviews with policy actors across Canada, our results suggest that the deployment of the first assisted migration policy in Canada successfully avoided the controversy surrounding the idea in the scientific community by changing the scientific discourse associated with best forest management practices. The shift from an ecological discourse to a genetics discourse over forest policy in British Columbia signals what we might expect in future forest adaptation policy development in Canada.
        Clearly, a genetics characterization of forests looks back to the distant past for guidance in future 'climate change fitness of species'. This represents a major conceptual shift, which significantly affects the temporal and spatial scales on which forest management planning occurs. This shift can be characterized, furthermore, by the deployment of new normative goals for forest management: rather than trying to recreate current forest composition and functions, the values and norms guiding forest management from a genetics perspective seek to accelerate forest transition to the future, to a 'climate resilient' state. This normative shift has real material consequences, such as enabling the movement of western larch 1000 km north of its current distribution, sidestepping the issue of its ecological appropriateness in the recipient ecological community, because from a 'climate fitness' perspective, western larch may eventually migrate to northern BC.
        Thus given the genetical frame structuring the AM policy coordinative discourse, we argue that there is a major shift in the cognitive and normative content of ideas at the program level. However, when we analyzed the communicative discourse on western larch AM policy, we found that concerted efforts were taken by policy developers to downplay the significance of this program change in their communication to the public. To begin, educational and training outreach activities stressed the low risk associated with population range expansion, as the following interviewee explains: "We are very open and inclusive in talking about AM. I talk about the risk of action and inaction and more importantly the difference between the various forms of AM. We are very clear that we are not testing or interested in exotic translocations."
        To sum up, our analysis suggests that policy analysts, forest geneticists and policy implementers in the BC Tree Improvement Branch characterized forests so as to highlight and diffuse an evolutionary theory of forest ecosystems that is tied to a new set of norms and values associated with a humanistic philosophy that are highly controversial in the conservation community—yet which, in turn, are signals of major institutional change in forest policy in BC. . .  Our results suggest that the deployment of the first AM policy in Canada has successfully avoided the philosophical debates on AM in the conservation scientific community by changing the scientific discourse associated with best forest management practices (i.e., from an ecological point of view to a genetics point of view) and this discursive shift may signal what we might expect in future forest adaptation policy development in Canada.

  • "Location, Location, Location: Assisted Migration May Be Coming Closer to a Reality as a Response to Climate Change" by Yee Huang in CPR Blog, (01 February 2011)
    "In the UK, the Environment Agency is "exploring" moving thousands of vendace and schelly, both freshwater white fish, from the northern Lake District in England to cooler waters in Scotland. While still in the planning stages, this strategy represents a remarkably specific and dramatic response to climate change." Includes link to the UK study mentioned.

  • "Assessing the potential for urban trees to facilitate forest tree migration in the eastern United States," C.W. Woodall et al in Forest Ecology and Management 259 (2010) 1447-1454
    "The goal of this study was to compare tree species compositions in northern urban areas to tree compositions in forestland areas in the eastern U.S. as an indicator of the potential for urban trees to facilitate future forest tree species migration. Results indicated that a number of tree species native to eastern U.S. forests of southern latitudes are currently present in northern urban forests."

  • "Conservation Biology: The End of the Wild" by Emma Marris, Nature 12 January 2011, 469:150-52
    "Climate change means that national parks of the future won't look like the parks of the past. So what should they look like? . . . [National Park Service director Jonathan] Jarvis has suggested the possibility of moving species outside their native ranges to give them a better chance of surviving — just not right away. "The big point here is that we are willing to face these questions," he says. "We are not afraid to talk about them."

    SEE ALSO an Dec 2010 online interview with NPS Director Jonathan Jarvis on climate change and park management, including "assisted migration".

  • "Climate Change Risks and Conservation Implications for a Threatened Small-Range Mammal Species" by Morueta-Holme et al., PLOS One29 April 2010
    "Here, we provide a detailed assessment of the climate sensitivity and potential distributional impacts of 21st century climate change for an illustrative endemic species limited to a restricted part of the Mediterranean region. This region is rich in endemic species and is expected to experience particularly severe global-change-driven biodiversity losses over the 21st century. The study species is the Iberian desman Galemys pyrenaicus (E. Geoffroy Saint Hilaire, 1811), a small semi-aquatic mammal endemic to the Iberian Peninsula.

  • "Big Moving Day for Biodiversity: A macroecological assessment of the scope for assisted colonization as a conservation strategy under global warming" by Jens-Christian Svenning, IOP Conf. Series: Earth and Environmental Science 8 (2009) 012017
    12-page report in PDF

  • "Wildlife Service Plans for a Warmer World" news report by Janet Fang, NatureNews Published online 17 March 2010 | Nature 464, 332-333 (2010) | doi:10.1038/464332a
    The report, a collaboration between the USFWS, the US Geological Survey, academics and a collection of environmental and wildlife groups, quantified the vulnerability of each species on the basis of its breeding behaviour, habitat, migratory pattern and ecological niche. George Wallace, vice-president for oceans and islands at the American Bird Conservancy in The Plains, Virginia, says the report shows that "we need to consider climate change as we continue conservation work into the future".

  • "Temperature-Dependent Sex Determination and Contemporary Climate Change" by N.J. Mitchella, F.J. Janzen. Journal: Sexual Development, published online, only abstract freely available (9 February 2010)
    Whether species that have persisted throughout historic climatic upheavals will survive contemporary climate change will depend on their ecological and physiological traits, their evolutionary potential, and potentially upon the resources that humans commit to prevent their extinction. For those species where temperatures influence sex determination, rapid global warming poses a unique risk of skewed sex ratios and demographic collapse. Here we review the specific mechanisms by which reptiles with temperature-dependent sex determination (TSD) may be imperilled at current rates of warming, and discuss the evidence for and against adaptation via behavioural or physiological means. We propose a scheme for ranking reptiles with TSD according to their vulnerability to rapid global warming, but note that critical data on the lability of the sex determining mechanism and on the heritability of behavioural and threshold traits are unavailable for most species. Nevertheless, we recommend a precautionary approach to management of reptiles identified as being at relatively high risk. In such cases, management should aim to neutralise directional sex ratio biases (e.g. by manipulating incubation temperatures or assisted migration) and promote adaptive processes, possibly by genetic supplementation of populations.

  • "Ecological History and Latent Conservation Potential: Large and Giant Tortoises as a Model for Taxon Substitutions" by Dennis M. Hansen et al. Ecography: 33: 272-84 (2010)
    This paper is listed here, as well as among the "rewilding" links at bottom, because while advocating carefully assessed and monitored "taxon substitutions" of tortoises (that is, re-introducing herbivorously similar large and giant tortoises into landscapes, especially islands, where the endemic species were exterminated by humans or shifting sea levels within historic or prehistoric time), the authors also suggest that it would be helpful for the IUCN to include in its current work to develop express international guidelines for managing the need to engage in climate-induced "assisted migration/translocation" guidelines as well for "taxon substitutions": "Despite global potential for resurrecting lost species interactions and restore degraded ecosystem functions, taxon substitutions remain controversial. We suggest that a healthy debate on the applicability of taxon substitutions could be facilitated by including guidelines for them within an expanded IUCN species translocation framework. This would have the added benefit of promoting species interactions and functional integrity of ecosystems as integral parts of all translocation projects. Furthermore, conducting taxon substitutions and reintroductions within a proper experimental framework will facilitate the interpretation of ecosystem responses

  • "The Velocity of Climate Change" by Scott R. Loarie et al. Nature, 462, 1052-1055 (24 December 2009)
    Important scholarly/scientific work that results in an estimate of 1/3 mile per year on average of latitudinal shift in climate and only 8% of protected lands being large enough to include today's climate within its bounds in a century. The abstract only is available for free online, at the url above, but you can read a news report of it at Discovery News.

  • "From Reintroduction to Assisted Colonization: Moving along the Conservation Translocation Spectrum" by Philip J. Seddon, opinion article in Restoration Ecology 2010
    "Historic distribution records will always provide a good starting point for identifying translocation release sites, but global climate change and the dynamic nature of ecosystems mean that historical species ranges have only limited use. Other, even pre-historic reference points, and species-specific habitat suitability assessments should be considered.
        "Single-species conservation actions in the core of historic range will remain the backbone of many conservation efforts, but increasingly we need to adopt an ecosystem focus and consider the translocation of suites of species to restore key ecological functions. Ecological functions once performed by now-extinct taxa can be restored through the introduction of ecological replacements, which may themselves be threatened in their native range."

  • "Big Moving Day for Biodiversity? A macroecological assessment of the scope for assisted colonization as a conservation strategy under global warming" by Jens-Christian Svenning et al. IOP Conf. Series: Earth and Environmental Science, 8 (2009) 012017
    clip from ABSTRACT: "Our results suggest that there is substantial room for additional plant species across most areas of Europe, indicating that there is considerable scope for implementing assisted colonization as a proactive conservation strategy under global warming without necessarily implicating negative effects on the native flora in the areas targeted for establishment of translocated populations. Notably, our results suggest that 50% of the cells in Northern Europe, the likely target area for many translocations, could harbor at least 1/3 as many additional species as they have native species."

  • "Return of the Ericads: Students Dig and Reestablish a Prehistoric Species", by Michael Heim, Journal American Rhododendron Society, Winter 2010
    Michael Heim is a science teacher at Lac Courte Oreilles Ojibwe High School, Hawyard WI, whose students planted in May 2009 cloned cuttings from a very rare eastern native: the evergreen Box Huckleberry, Gaylussacia brachycera. The 2 page, photo-rich PDF of this article is a fascinating look at "rewilding" of an endangered species, based on a "deep-time" perspective in which "native" is regarded as including a plant's presumed preglacial regional distribution. In a March 5 comment posted on the Torreya Guardians site, Heim reports that he and his students have also planted cuttings from clones of Torreya taxifolia and Taxus floridana on the same tribal forest lands next to the school in northern Wisconsin, thus signifying another citizen-initiative of assisted migration, based on a deep-time understanding of native range.

  • "Assisted Colonization: Integrating Conservation Strategies in the Face of Climate Change", by Scott R. Loss et al., Biological Conservation, December 2010
    A 3-page comprehensive review of the major papers and arguments, primarily useful for all the linked references. It is too compressed to be useful for fully understanding the major implications. As with virtually all the published papers through 2010, the major argument against assisted migration is risk of invasiveness in its targeted new range. And as with all its predecessor papers cited, it fails to put this issue in the context of deep time: that is, it fails to recognize that species that may be considered for assisted migration are millions (even tens of millions) of years old, and have been moving vast distances independently of one another north and south and also up and down mountains throughout the significant climate shifts of the Pleistocene epoch, and before. This point is brought out in one key paper cited in this review article. It is the paper by Mueller and Hellman, 2008: "An Assessment of Invasion Risk from Assisted Migration", which concludes that N-S translocations of land species on the same continent pose relatively little risk, while moving crustaceans and fish between aquatic watersheds evidences a history of problems. The strongest advocacy of a deep-time perspective is by Connie Barlow of Torreya Guardians, in her 2005 paper (co-authored with Paul S. Martin): "Bring Torreya taxifolia North Now" and her 2011 onine piece: "Assisted Migration (Not Assisted Colonization) for Endangered Torreya".

  • "A Hunt for Seeds to Save Species, Perhaps by Helping Them Move" science journalist article by Ann Raver, New York Times, 9 November 2009.
    "Scientists from the [Chicago Botanic Garden] are sending teams out across the Midwest and West to the Rocky Mountains and Great Basin to collect seeds from different populations of 1,500 prairie species by 2010, and from 3,000 species by 2020. The goal is to preserve the species and, depending on changes in climate, perhaps even help species that generally grow near one another to migrate to a new range." "'We recognize that climate change is likely to be very rapid and that seeds only disperse a few hundred yards, half a mile at most, naturally,' said Kayri Havens, the botanic garden's director of plant science and conservation. 'They'll need our help if we want to keep those species alive.'"

  • "Assisted Migration of Plants: Changes in Latitudes, Changes in Attitudes" by Pati Vitt et al., Biological Conservation, 23 September 2009.
    Excerpt: "Intra-continental translocation has also proven an important conservation tool to help species escape diseases driving them to extinction in their native range. This includes numerous Australian species like Lambertia orbifolia (roundleaf honeysuckle), declining due to the devastating effects of Phytophthora cinnamomi (root rot fungus disease). For these species, translocation has been employed as a conservation measure since the mid-1990s (Cochrane, 2004), and in the United States, the formerly abundant Florida Torreya (Torreya taxifolia) has lost at least 98.5% of its former population size since the 1900s due largely to disease (Schwarz et al., 2000). Since 1989, ex situ collection and propagation, as well as translocation, have become key modes of conservation for the species. The Torreya Guardians, a group of citizens undertaking the translocation of the Florida torreya, now cite climate change as an additional rationale for movement of the species outside its historic range (Barlow and Martin, 2005), though the practice is not universally accepted (Schwartz, 2005; Ricciardi and Simberloff, in press).
        "Translocating plants is not without risk, the most problematic is the potential for a species to become invasive in its introduced range. Intercontinental movement of species has indeed resulted in problems with invasive species, but the vast majority of introduced species do not become invasive. It is estimated that less than 1% of species become invasive when imported to a new range (Williamson and Fitter, 1996), and only a small percentage of those (7.5% of invasives in the US) are a result of intra-continental introductions (Mueller and Hellmann, 2008). Most discussions of assisted migration in the context of climate change involve moving species relatively short distances poleward or higher in elevation within a continent, and many focus on species with limited dispersal ability which are less likely to become weedy (Rejmanek and Richardson, 1996). In many anthropogenically fragmented habitats, migration assistance in the form of short distance jump dispersal or corridor creation may be necessary for species to survive. These types of dispersal pathways are less likely to result in enemy release and biological invasion than are long distance and mass dispersal (Wilson et al., 2009).
        "We envision a future where well-conceived translocations of species may reduce the risk of extinction, as well as in- crease the number of potential taxa creating new assemblages in a fluid landscape responding to broad scale changes.
        "While we debate about whether and how to implement assisted migration strategies, species already at risk are being further stressed by the unpredictability of the environmental changes they are experiencing. For plants, at any rate, the solution seems clear: collect and bank them now, and then plan the implementation stage when it is appropriate. As Hunter (2007) points out: implementation of an ex situ conservation strategy is far less problem- atic for plants, and a great deal less expensive, than for other taxa of conservation interest.
        "Ultimately, implementation of assisted migration, or other large scale conservation mechanisms, will require reconciliation be- tween the hubris of being able to control nature, with the hubris that humans are somehow not a part of nature. Incorporating the newly emerging science of restoration genetics, and the lessons learned from both rare plant translocation experiments and the practice of restoration ecology will provide a road map for how to design assisted migration events. While natural communities of the future may not have current day analogs, our job is to ensure that they are as species-rich and genetically-diverse as possible."

  • "Climate Change Science Compendium 2009" by United Nations Environment Program (UNEP). September 2009
    Massive new report that goes beyond the usual IPCC report to make clear how the likely adverse effects of climate change are now thought to be much greater than even the IPCC reported. The section on "Management" contains a subsection on "Assisted Colonization" (p. 46 of the report; p. 4 of the PDF download), that includes these statements: "The reality of a rapidly changing climate has caught many natural-resource managers and policy-makers unprepared. Large-scale translocations might now be needed. Consequently, the conservation community needs to move beyond the preservation or restoration of species and ecosystems in place as the correct approach." and "Assisted colonization will always carry some risk, but these risks must be weighed against those of extinction and ecosystem loss. Already some regions of the Earth such as the Arctic are experiencing high levels of warming. Many others will experience unprecedented heat within the next 100 years, as well as altered precipitation and ocean acidity. The future for many species and ecosystems is so bleak that assisted colonization might be their best chance. These management decisions will require careful thought and will need to be backed up by detailed scientific understanding if they are to succeed."

  • "Science Journal Podcast" AAAS transcript. 24 September 2009
    One of the topics covered is the scientific controversy over the pros and cons of assisted migration. The work of citizen group Torreya Guardians is mentioned. (In PDF, so do internal Find search for "assisted migration".)

  • "Garden Plants Get a Head Start on Climate Change" by Sebastiaan Van der Veken et al, May 2008, Frontiers in Ecology and the Environment
    "We compared the natural ranges of 357 native European plant species with their commercial ranges, based on 246 plant nurseries throughout Europe. In 73% of native species, commercial northern range limits exceeded natural northern range limits, with a mean difference of ~ 1000 km. With migration rates of ~ 0.1 - 5 km per year required for geographic ranges to track climate change over the next century, we expect nurseries and gardens to provide a substantial head start on such migration for many native plants. While conservation biologists actively debate whether we should intentionally provide "assisted migration", it is clear that we have already done so for a large number of species." (excerpt from Abstract)

  • "Mapping California's Shifting Climate" KQED Climate Watch blog. 26 February 2010
    Cross-institutional report, with maps, on possible occurrence and velocity of climate change in California, along with response alternatives.

  • "Climate Change Turns Conservationists into Triage Doctors" CBC News (Canada). 30 November 2009
    Survey of a shift in conservationists attitudes: "The point is not to think outside the box, but to recognize that the box itself has moved and, in the 21st century, will continue to move more and more rapidly," University of Colorado ecologist Timothy Seastedt and his colleagues write in the journal Frontiers in Ecology and the Environment. Seastedt and others argue land managers must focus on ecosystem diversity to give plants and animals the best chance to adapt to the change scientists say is coming: The more diversified a system, the more resilient. Trying to return ecosystems to some historic or natural state is no longer possible, they say. "To be honest, the combination of climate and atmospheric chemistries we're experiencing now — you can't find any historical match," Seastedt says.

  • 2009 book highlights ASSISTED MIGRATION controversy, Heatstroke: Nature in an Age of Global Warming, by Anthony Barnosky (Island Press)
    Publisher's press release excerpt: Unfortunately, both assisted migration and Pleistocene rewilding would lead to managed ecosystems — the antithesis of wilderness. Just as we manage fisheries to preserve an important food source, we will have to give up some wildness in order to preserve species. "We can't protect all three faces of nature — ecosystem services, like clean water and fisheries; species diversity; and the feeling of wilderness — without somehow separating those three different concepts of nature and working with each one of them differently," [the author] says. "All can be complementary, but you have to do different things for each one. I think there are people who are quite happy to settle for one or two of those, but my personal philosophy and feeling is that we can have all three faces of nature." [The author] foresees two types of preserves, for example: species preserves to protect a species or assemblages of species, but requiring heavy management; and wildland preserves that retain ecological interactions without the influence of humans — the feel of wilderness — but which will see changing species and even extinctions.

  • "Hot Issue: Should We Deliberately Move Species?" Assoc. Press, 19 July 2009.
    Reports on the work of Greg O'Neill, a geneticist with the British Columbia Ministry of Forests and Range, who is already working with logging companies to replant logged forests in British Columbia not with the species that were logged, but with seeds of species currently native to much lower elevations or latitudes. [Same story also online at:]

  • "Butterflies Reeling from Impacts of Climate and Development" Proceedings National Academy of Sciences January 2010.
    Their most significant findings: 1. Butterfly diversity (the number of different species present) is falling fast at all the sites near sea level. It is declining more slowly or holding roughly constant in the mountains, except at tree line. 2. At tree line, butterfly diversity is actually going up, as lower-elevation species react to the warming climate by moving upslope to higher, cooler elevations. 3. Diversity among high-elevation butterflies is beginning to fall as temperatures become uncomfortably warm for them and, Shapiro says, "There is nowhere to go except heaven."

  • "Some California Amphibians May Need a Lift to Survive Climate Change" Scientific American online, by Brendan Borrell, 7 August 2009.
    "As temperatures rise over the next century, three California amphibian species could be pushed to the cusp of extinction because the warming climate will effectively block their migration to more suitable habitats. Interventions by humans who physically relocate the animals may be the only way to help them survive. . . The Torreya Guardians, a self-organized group of naturalists, botanists, ecologists and others, are the most well-known proponents of assisted migration. Last July, the group planted endangered Torreya taxifolia seedlings in new habitat patches north of their customary domain in Florida, where it is becoming too hot for the conifers to survive." (and more)

  • "Are Butterflies the Silent Harbinger of Global Warming?" report by journalist Seth Shulman, Grist, 17 June 2010.
    Excellent summary of Camille Parmesan's early and continuing leadership in pointing out the shift poleward and upslope in native range of butterfly and other species, including her landmark 1996 and 2003 papers in the journal Nature. Parmesan is the lead scientist on the United Nation's Intergovernmental Panel on Climate Change (IPCC).

  • "Driving Mr. Lynx" Ideas page article by journalist Chris Berdik, Boston Globe, 12 October 2008.
    Lengthy news article that surveys the assisted migration debate, from its roots in a 2004 article in Wild Earth journal to citizen-activism, scientific backlash, and the beginnings of a worldview shift. The work of Torreya Guardians is highlighted, along with the August 2008 official filing, under the Endangered Species Act, of a request (by scientist Camille Parmesan) to undertake the first intentional movement of an animal species (an endangered butterfly) in response to shifting climate.

  • "Rules of the Wild", sidebar to above article in Boston Globe, 12 October 2008.

  • "Moving on Assisted Migration" news report by Emma Marris, Nature, online 28 August 2008.
    One of the top journals in science reports on the article (immediately below) that had been published in the other top science journal, plus coverage of the special session on assisted migration at the Ecological Society of America meeting in August 2008. Torreya Guardians is presented as taking the action lead in pressing for a rethinking of how biodiversity is best protected.

  • POLICY FORUM: ECOLOGY: "Assisted Colonization and Rapid Climate Change" by O. Hoegh-Guldberg, L. Hughes, S. McIntyre, D. B. Lindenmayer, C. Parmesan, H. P. Possingham, and C. D. Thomas, in Science 18 July 2008: 345-346. PDF of original article
    This 2-page article in America's top science journal has spurred enormous coverage and debate over the topic of what was once known as "assisted migration". Click here for news reports of the article:

  • Earth News online (posts full report of journalist Lauren Morello, who interviewed Connie Barlow of Torreya Guardians to demonstrate the citizen-action side of the issue)
  • (a spin-off report that mentions the work of Torreya Guardians)
  • Scientific American online (a spin-off report that mentions Torreya Guardians)
  • in Wired News
  • Wired Magazine commentary by Brandon Keim
  • Science Daily (online)
  • Official website "Managed Relocation" posted by the "Working Group" that formed at the Ecological Society of America meeting, August 2008.
    Content: Right now this is just a skeleton website, as the group goes about its work. But after it achieves a product, estimated for autumn 2009, this will be a key site to watch. Right now, you can find a list of group leaders and members on that site. Check out their LIST OF PUBLICATIONS AND MEDIA REPORTS on this topic.

  • University of Queensland interview with first author of the Science forum above.
    Hoegh-Guldberg says, "If we are to take the latest climate science seriously, then our current conservation strategies will not work for the majority of the species. To be blunt, they need to change. Even under the mildest rates of climate change, the habitat of many species will contract. Consequently, the future for many species and ecosystems is so bleak that assisted colonisation might be their only chance of survival."

  • "Can Assisted Migration Save Species from Global Warming?" Scientific American, March 2009
    A lengthy article featuring Camille Parmesan, first advocate for assisted migration among professional conservation biologists. Lots of excellent details on butterflies and other species threatened by climate change. Mentions work of Torreya Guardians in assisting Torreya taxifolia tree seedlings to venture northward in July 2008.

  • U.S. Fish & Wildlife Service "Internal Discussion Draft: Rising to the Urgent Challenges of a Changing Climate: Strategic Plan for Responding to Accelerating Climate Change in the 21st Century". Draft of 12 December 2008.
    "We will review, identify, and work to revise all elements of the Service's legal, policy, and regulatory framework necessary to support effective adaptive responses to changing climate. We will place particular focus on developing necessary new policies (e.g., assisted colonization) and needed revision of existing policies (e.g., what constitutes native, invasive, or exotic species?)." p. 15 "Novel conservation and recovery actions, such as assisted colonization, will be developed and implemented to protect acutely climate-vulnerable species." (p. 16)

  • "Assisted colonization is not a viable conservation strategy"(preprint of 2009 Trends in Ecology and Evolution paper) by Anthony Ricciardi and Daniel Simberloff
    Strong argument against assisted migration in top ecological journal. Excerpt: "Until we develop more accurate and general methods of predicting the impact of introduced species, cost-benefit analyses will be dangerously misleading. It is not yet possible to quantify the probability that a given species will go extinct because of climate change, or that a translocated species will harm one or more native species in a recipient community. To compare two such illusory numbers would lead to a false sense of scientific certainty. . . . Given this lack of predictive power, assisted colonization is tantamount to ecological roulette and should probably be rejected as a sound conservation strategy by the precautionary principle."

    Note: A letter to TEE journal commenting on the above is "Assisted colonization is a techno-fix" by Ioan Fazey and Joern Fischer.

  • "Why Saving a Species is a Mathematical Matter", 26 July 2011 news article online in Brisbane Times.
    Interview with lead author, Eve McDonald-Madden, of July 2011 paper in Nature Climate Change, "Optimal timing for managed relocation of species faced with climate change", with example of Australia's Golden Bowerbird. See also article in Live Science.

  • "Should Species Be Relocated to Prevent Extinction", by Devin Powell, Inside Science News Service, 24 August 2009
    EXCERPT: The most recognized assisted migration project to date may be the Torreya Guardians. This network of conservationists, which includes botanists and ecologists, is trying to save the Torreya taxifolia, an endangered evergreen that grows to 60 feet in height. The group has transplanted dozens of trees from the Florida panhandle, where it is rapidly disappearing, to sites in North Carolina that are thought to have a suitable climate. "Plants are so much easier to replicate than pandas," said Rob Nicholson of the Botanic Garden at Smith College in Northampton, MA. "Torreya roots easily ... and you could start knocking them out by the tens of thousands if you wanted to."

  • Science Writer Carl Zimmer surveys the assisted migration controversy, as of 6 May 2006 in "As climate warms, species may need to migrate or perish", published online in ONLINE OPINION: Australia's e-journal of social and political debate.
    Zimmer's survey includes the context of the Ricciardi and Simberloff paper (directly above), and Jessica Hellman's comment on that paper, where she says, "Is the alternative just to forsake a species?" she asks. "I just don't want to sit back and say, 'Oh the world is going to hell'."

  • "Bugs: The Forgotten Victims of Climate Change", 3 July 2009 news article online in Live Science.
    Surveys managed relocations controversy as it pertains to insects; mention of need to assess insect tolerance of climate change in all their life stages; quotes Jessica Hellman.

  • "Big Plans for a Little Butterfly", 6 July 2009 news article online Mercury News.
    Project proposed to re-introduce extinct populations of Bay Checkerspot at the famous site where Paul Ehrlich and students studied them for 5 decades: "'We may end up having to try to readjust natural communities all over the planet,' Ehrlich warned. 'Reintroduction is a dice game,' said Carol Boggs, a Stanford biologist who would direct the experiment. 'What we'd like to understand is how to load the dice in our favor. And this is the perfect place to try it.' Researchers will spend the next year designing the experiment, which must be approved by both Stanford officials and the U.S. Fish and Wildlife Service. Stanford spokesman Larry Horton cautions that the university has not yet taken a position. The U.S. Fish and Wildlife Service, which protects endangered species, said it would support the effort, if done correctly. The Stanford scientists would use contrasting strategies — perhaps introducing insects at different phases in the life cycle, into different plots, at different seasons, Boggs said. Mowing, grazing or other human interventions would be needed to sustain it. By managing the introduction, Stanford scientists would build, in essence, a butterfly lab."

  • "University of Otago Rock Wren Project", 6 July 2009 online New Zealand abstract of new research project.
    Project abstract discusses methods to help ailing New Zealand bird, including assessment of assisted migration.

  • "Assisted Colonization: CBC Radio Interview"
    A terrific AUDIO exploration of the controversy, which aired 24 July 2008. Part 1 is the supportive side, via an interview with Prof. Camille Parmesan. Part 2 is an interview with an invasive species researcher that is very critical of the idea. Part 3 is a not-to-be-missed radio spoof of the idea.

  • "Rewilding Torreya taxifolia to Waynesville, North Carolina, July 2008" Torreya Guardians webpage posted by Connie Barlow, August 2, 2008.
    A richly illustrated PHOTO-ESSAY, with links to a complete chronology, of the REWILDING ACTION that Torreya Guardians undertook for 31 potted seedlings. A writer and a photographer commissioned by Audubon magazine documented the action (which will probably be published in a summer 2009 issue of Audubon.

  • "Terrestrial Orchid Conservation in the Age of Extinction", Annals of Botany 2009 104(3):543-556.
    Excerpt: "Assisted translocation/migration represent new challenges in the face of climate change; species, particularly orchids, will need artificial assistance to migrate from hostile environments, across ecological barriers (alienated lands such as farmlands and built infrastructure) to new climatically buffered sites. It is likely that orchids, more than any other plant family, will be in the front-line of species to suffer large-scale extinction events as a result of climate change."
        See also an online biogeographic article that reports on the existing use of assisted migration for Australian orchids.

  • "Orchids Flourish with Assisted Migration", Yale Environment Review (of June 2012 paper in Biological Conservation by Hon Liu et al).
    Excerpt: A recent study in Biological Conservation announced success with the migration of one of the worldÕs most beloved and charismatic plants: orchids. Chinese researchers examined the effects of assisted migration during a massive orchid rescue effort in 2006 that relocated 1000 endangered plants of 29 rare and endangered species from a lowland area that would be flooded by a hydropower project in the Longtan reservoir in Guangxi, southwestern China. Individual plants were moved 30 kilometers southeast to an altitude of 1000 meters above sea level, 600 meters higher than their original setting. Researchers labeled and mapped 462 individual plants from 20 species and tracked their flowering and survival six times over a 5-year period following the migration. The relocation area was situated outside the native elevation range of 70 percent of the species, offering the opportunity to compare responses between individuals within and outside of their native range. The researchers found that nearly all orchids were remarkably resistant to the climatic and grazing pressures, and that all species flowered in the new conditions.

  • "Species on the Move" June 8, 2009 May 28, 2009 ABC Science (online) report by Dani Cooper
    Lots of excellent details on the AUSTRALIAN species for whom assisted migration is being assessed, plus scientists quoted pro and con.

  • "Climate Change and Translocations: The Potential to Re-establish Two Regionally Extinct Butterfly Species in Britain", Biological Conservation, Matthew J. Carroll et al.
    ABSTRACT: Climate change is causing many organisms to migrate to track climatically-suitable habitat. In many cases, this will happen naturally, but in others, human intervention may be necessary in the form of "assisted colonisation." Species re-establishments in suitable parts of their historic ranges provide an opportunity to conserve some species and to test ideas about assisted colonisation. Here, bioclimatic models of the distributions of two extinct British butterflies, Aporia crataegi and Polyommatus semiargus, were used to investigate the potential for re-establishment in Britain. . .

  • "Assisted Colonization Key to Species' Survival in Changing Climate" Feb 19, 2009 Innovations Report.
    Detailed news report of "the first successful test case of assisted colonization". In 1999 and 2000, scientists introduced populations of two species of butterfly miles north of their then-current range in England. A just-published paper reports the results:
    Source: Willis, S.G. et al. 2009. Assisted colonization in a changing climate: a test-study using two U.K. butterflies. Conservation Letters DOI: 10.1111/j.1755-263X.2008.00043.x. Their abstracts concludes, "We suggest that assisted colonization may be a feasible and cost-effective means of enabling certain species to track climatic change."

  • "Assisted Migration" chapter of 2007 PhD thesis by the scientist who coined the term: Brian Keel.
    The full title of Keel's thesis is "Assisted Migration as a Conservation Strategy for Rapid Climate Change: Investigating Extended Photoperiod and Mycobiont Distributions for Habenaria repens Nuttall (Orchidaceae) as a Case Study". The link above connects to a PDF of his chapter 3. Note: His PhD thesis abstract is available online and in book format: Assisted Migration as a Conservation Strategy for Rapid Climate Change: Investigating Extended Photoperiod and Mycobiont Distributions of Habenaria Repens Nuttall (Orchidaceae) as a Case Study. Keel is also coauthor of a chapter on Managed Relocation in a 2012 edited volume, Plant Reintroduction in a Changing Climate: Promises and Perils.

  • "Defining Migration" chapter of the Brian Keel thesis, above.
    This short chapter will be useful for those engaged in considering whether "assisted migration" or "assisted colonization" is the best term for the kinds of conservation actions now beginning to be considered.

  • "Assisted Migration or Assisted Colonization: What's in a Name?" commentary posted on Torreya Guardians website.
    Torreya Guardians (and others) are invited to post comments on whether the original term, "assisted migration," should be replaced with the term more recently proposed, "assisted colonization."

  • "Joshua Trees Nearly Wiped Out by 2100?" by Jessica Marshal, 25 March 2011, Discovery News.
    "Ken Cole of the U.S. Geological Survey in Flagstaff, Ariz., and an interdisciplinary group of colleagues used information about the current distribution of Joshua trees combined with climate models to predict where the trees may be by 2070 to 2099." Using Pleistocene evidence in extinct ground sloth dung, data on the lack of recent reproduction in Joshua Tree National Monument (California), this tall member of the Yucca plant type, becomes the "poster plant" for "assisted migration" in the American West. Joshua Tree National Monument was, as it turns out, created too close to the southern edge of the 20th-century range of Joshua Trees, and thus may be doomed to loss of its namesake plant. See also, "Joshua Trees Losing Ground, Fast".

  • "Ground Truthing" blog post by Chris Clarke, 17 January 2008
    Revisits a previous blog on the possible extinction of California's Joshua Tree, owing to an inability to disperse and thus track climate changes. In this blog, Clarke mentions the work of Torreya Guardians in assisting migration of a critically endangered tree in eastern North America.

  • "Outlook Bleak for Joshua Trees" NPR online article and "All Things Considered" audio, 4 February 2008
    Interview of scientists and managers working in Joshua Tree National Park; prospects for the extirpation of Joshua Trees in the park as climate changes; the role of extinct ground sloths in past seed dispersal of this tallest of all yuccas. Audio interview of a trip to a cave looking for sloth dung.

  • "When Worlds Collide" by Douglas Fox, Conservation Magazine, Jan-March 2007 (cover story).
    Subtitle: "Climate change will shuffle the deck of plants, animals, and ecosystems in ways we've only begun to imagine."
    Content: Surveys beginnings of debate about whether to actively assist species in shifting their geographic ranges. The work of Torreya Guardians is mentioned.

  • "A Framework for Debate of Assisted Migration in an Era of Climate Change" by Jason S. McLachlan, Jessica J. Hellman, and Mark W. Schwartz, Conservation Biology, April 2007, Vol 21: 297-302.
    Content: The paper begins, "The Torreya Guardians are trying to save the Florida torreya from extinction. . . The focus of Torreya Guardians is an 'assisted migration' program that would introduce seedlings to forests across the Southern Appalachians and Cumberland Plateau. Their intent is to avert extinction by deliberately expanding the range of this endangered plant over 500 km northward. . . If circumventing climate-driven extinction is a conservation priority, then assisted migration must be considered a management option. . . Assisted migration is a contentious issue that places different conservation objectives at odds with one another. This element of debate, together with the growing risk of biodiversity loss under climate change, means that now is the time for the conservation community to consider assisted migration. Our intent here is to highlight the problem caused by a lack of a scientifically based policy on assisted migration, suggest a spectrum of policy options, and outline a framework for moving toward a consensus on this emerging conservation dilemma."

  • "Assisted Migration: Helping Nature to Relocate" by Bob Holmes, New Scientist, 3 October 2007.
    Content: Superb and lengthy science reporting on the above paper that appeared in Conservation Biology, with much additional information, insights, and arguments culled from the authors and other scientists and conservation managers. Highlights issues related to speed of migration (past evidence as well as estimates of future needs) and regional changes in climate. An article referenced within the report by Jason McLachlan et al., is also important to read: "Molecular Indicators of Tree Migration Capacity Under Rapid Climate Change" in Ecology, 2005, Vol 86, pp. 2088-98.

  • "A Radical Step to Preserve Species: Assisted Migration" by Carl Zimmer, New York Times (Science Times), 23 January 2007 (lead story).
    Zimmer's next NYT story is 18 Sept 2014: "For Trees Under Threat, Flight May Be Best Response". EXCERPT: "Traditionally, conservation biologists have sought to protect endangered plants and animals where they live, creating refuges where species can be shielded from threats like hunting and pollution. But a refuge won't help the whitebark pine, and so now scientists are pondering a simple but radical new idea: moving the trees to where they will be more comfortable in the future. It's called assisted migration, and the debate over its feasibility comes as biologists everywhere begin to reassess their tactics and the impact of climate change on endangered species."

  • "You-Tube video of Jessica Hellman on insect assisted migration", Notre Dame Research 3-minute documentary.
    Content: Great intro for popular audiences; shows lab experiments with insects in climate simulated settings.

  • "Don't Judge Species on Their Origins" comment by Mark Davis et al., Nature, 9 June 2011.
    Excerpt: "Today's management approaches must recognize that the natural systems of the past are changing forever thanks to drivers such as climate change, nitrogen eutrophication, increased urbanization and other land-use changes. It is time for scientists, land managers and policy-makers to ditch this preoccupation with the native v. non-native dichotomy and embrace more dynamic and pragmatic approaches to the conservation and management of species — approaches better suited to our fast-changing planet.

  • "U.S. Agrees to Consider Protection for Pikas" report by Jane Kay in San Francisco Chronicle, 13 February 2009.
    Endangered Species Act invoked by Center for Biological Diversity to protect pikas threatened by global warming in the alpine peaks home in mainland U.S. No mention yet of assisted migration for the subspecies of pika trapped on warming mountain tops.

  • "Threatened Species 'Need Help' Finding Cooler Homes" news report by Catherine Brahic New Scientist Environment (online), 18 July 2008.
    News report on the 18 July 2008 paper in Science by Hoegh-Guldberg et. al (above).

  • "What Another Century of Global Warming Could Do to Our Wilderness" by Bert Gildart in Wilderness Magazine, September 2008.
    Great overview of looming problems for ecosystems (such as the Everglades) and species (such as Mountain Pica), some of which are already happening. No mention of assisted migration, of course, as this degree of human intervention would be a very delicate issue for the "wildest" of landscapes, especially for formally designated wilderness areas.

  • "Plants at Thoreau's Walden Pond Affected by Climate Change in the Area", Assoc. Press News Story, 27 October 2008.
    A 4.3 degree F. area-specific rise in temperature over the past century has affected plants in this sacred spot of environmentalism in Massachusetts. Notably, the plants hardest hit are those that did not alter their spring flowering time in tandem with the shift in earlier seasonal warming.

  • "Pre-emptive Strike: Outwitting Extinction", by Emma Marris, Nature Reports Climate Change (Online) 23 October 2008.
    The IUCN has issued a report on "climate change susceptible" species. "Assisted migration" is mentioned as one of the possible management responses, as well as enlarged biological preserves and focussing on entire ecosystems, not merely individual species.

  • "On the Use of Taxon Substitutes in Rewilding Projects on Islands" by Dennis M. Hansen, 2010, chapter in Islands and Evolution, Perez-Mellado et. al, eds.
    Extract: "I hope the examples here, as well as the case studies, will illustrate the potential for taxon substiution to rapidly move beyond the status of gimmck and become an integral part of restoration schemes for some of the most degraded habitats on our planet."

  • "Ecological History and Latent Conservation Potential: Large and Giant Tortoises as a Model for Taxon Substitutions" by Dennis M. Hansen et al. Ecography: 33: 272-84 (2010)
    ABSTRACT: Starting in the late 1970s, ecologists began unraveling the role of recently extinct large vertebrates in evolutionary ecology and ecosystem dynamics. Three decades later, practitioners are now considering the role of ecological history in conservation practice, and some have called for restoring missing ecological functions and evolutionary potential using taxon substitutes  extant, functionally similar taxa  to replace extinct species. This pro-active approach to biodiversity conservation has proved controversial. Yet, rewilding with taxon substitutes, or ecological analogues, is now being integrated into conservation and restoration programmes around the world. Empirical evidence is emerging that illustrates how taxon substitutions can restore missing ecological functions and evolutionary potential. However, a major roadblock to a broader evaluation and application of taxon substitution is the lack of practical guidelines within which they should be conducted. While the International Union for Conservation of Nature’s reintroduction guidelines are an obvious choice, they are unsuitable in their current form. We recommend necessary amendments to these guidelines to explicitly address taxon substitutions. A second impediment to empirical evaluations of rewilding with taxon substitutions is the sheer scale of some proposed projects; the majority involves large mammals over large areas. We present and discuss evidence that large and giant tortoises (family Testudinidae) are a useful model to rapidly provide empirical assessments of the use of taxon substitutes on a comparatively smaller scale. Worldwide, at least 36 species of large and giant tortoises went extinct since the late Pleistocene, leaving 32 extant species. We examine the latent conservation potential, benefits, and risks of using tortoise taxon substitutes as a strategy for restoring dysfunctional ecosystems. We highlight how, especially on islands, conservation practitioners are starting to employ extant large tortoises in ecosystems to replace extinct tortoises that once played keystone roles.

  • "Bolson Tortoises of the Pleistocene assisted to move north to New Mexico" New Mexico Wilderness Alliance, Rewilding Institute Website, January 2008.
    Content: 37 Bolson Tortoises (larger than a desert tortoise) were moved from a private ranch in Arizona to protected lands in New Mexico where they are being bred and managed expressly for "rewilding" into their former habitat.

  • "Beyond Historic Baselines: Restoring Bolson Tortoises to Pleistocene Range", by Joe Truett and Mike Phillips, in Ecological Restoration, June 2009, pp 144-151.
    Abstract: Ecological restoration in North America traditionally has strived to return ecosystems to some semblance of the early historic (post-Columbian) condition. Emerging alternative paradigms recognize the large impacts exerted by pre-Columbian peoples, the ever-changing nature of ecosystems regardless of anthropogenic effects, and the possibility of using other benchmarks. Recently, the Turner Endangered Species Fund initiated a project to restore the endangered bolson tortoise to an area in southern New Mexico within its late Pleistocene, but not historic range. Justifications included the likelihood that prehistoric humans extirpated it from New Mexico, the presence of habitats similar to those in its current range in Mexico, and escalating threats to species there. . . Restoring imperiled species to prehistoric ranges has some precedent in North America and, we believe, merits increasing consideration as historic ranges of some species offer increasingly less security.

  • "Mauritius: Back to Wildlife [Tortoises]" article in The Guardian Weekly Online, 22 September 2008.
    Content: Aldabran Giant Tortoises used as proxies for the Mauritius giant tortoises that had been exterminated. "Rewilding" a small island near Mauritius with these giant tortoises.

  • "Coevolution of Cycads and Dinosaurs" paper by George E. Mustoe, The Cycad newsletter, March 2007.
    Barlow and Martin 2004 proposed that Torreya taxifolia might have gotten trapped in its peak-glacial pocket reserve (in northern Florida) for lack of its coevolved seed disperser, and thus was unable to geographically respond to the warming interglacial climate. The above paper suggests that another taxon of gymnosperm that thrived (along with genus Torreya) in the Jurassic period might have suffered from an inability to easily track climate change when the seed-dispersing dinosaurs died out.

       Download in PDF two CLASSIC ARTICLES, for and against assisted
       migration of Torreya taxifolia, published as the featured
       Forum in the Winter 2005 issue of Wild Earth. Download
       the pro and con articles separately for printing on standard   
       size paper. Or, for viewing the 2-article Forum as it
       appeared in publication (wide-screen, with all illustrations),
       download the "Forum."

      FOR assisted migration, by Connie Barlow & Paul Martin  

      ANTI assisted migration by Mark Schwartz

      FORUM (both articles for wide screen)

  • "Biologists Debate Relocating Imperiled Species" by Philip Bethge Spiegel Online International (English edition) 23 November 2007.
    Content: News report on how climate change will threaten animal and plant species; includes coverage of Torreya taxifolia and mentions Torreya Guardians.

  • Discussion on a Blog Devoted to Snails and Slugs editorial, December 2008.
    Content: Blogs and comments debate "assisted migration/colonization" with respect to snails; includes some case history of attempt to relocated endangered snails from New Zealand mainland to an island off NZ.

  • "Some Endangered Species May Be Shifted to More Congenial Habitats" editorial, in The Times of India 3 February 2007.
    Content: Editorial in favor of assisted migration for endangered species.

  • "Climate Change and Assisted Migration of At-Risk Orchids" by Brian G. Keel, p. 9 of Orchid Conservation News (Woodland, CA), March 2005.
    Content: Advocacy and statement of conditions that merit assisted migration intervention for orchids

  • "Climate Change and Moving Species: Furthering the Debate on Assisted Colonization" by Malcolm L. Hunter, 2007, Conservation Biology Vol 21: 1356-58.
    Content: Makes case for using the term "assisted colonization" rather than "assisted migration"; proposes three features for testing advisability of any particular species for such intervention: (1) their probability of extinction due to climate change, (2) their vagility, (3) and their ecological roles.

  • "Climate Change Impacts and Adaptation: A Canadian Perspective" Natural Resources of Canada.
    Content: Governmental publication in favor of assisted migration of tree species in anticipation of climate change.

  • "A Landscape in Transit" by Betsy Mason, Contra Costa Times (Woodland, CA), 24 January 2007.
    Content: Effect of global warming on California blue oaks and other trees.

  • "Assisted Colonisation" blog by Andrew Guerin, 18 July 2007.
    Content: Marine biologist highly skeptical of the merits of considering assisted colonisation for marine species.

  • "Macquarie Biologist's Grave Warning on Species Survival", news report.
    Content: Professor Lesley Hughes, co-author of the 18 July 2008 paper in the journal Science (O. Hoegh-Guldberg et. al), is interviewed by the web news of her university. Also click on an AUDIO INTERVIEW with Professor Hughes (scroll down to 30 June 2008, "Climate Change Peril").

    Pleistocene Rewilding and Taxon Substitution for Ecological Restoration

         Paul S. Martin originated the concept of Pleistocene Rewilding and Taxon Substitution in the 1970s. You can learn more about his early work in that field by accessing this page: Tribute to Paul S. Martin.

    The VIDEO at left is an illustrated version of a 1996 phone interview Connie Barlow did with Paul specifically about his "Pleistocene Rewilding" concept.

  • "Is the Climate Right for Pleistocene Rewilding? Using Species Distribution Models to Extrapolate Climatic Suitability for Mammals across Continents", by Orien MW Richmond et al., PLoS One 5(9): e12899. doi:10.1371/journal.pone.0012899
    ABSTRACT begins: Species distribution models (SDMs) are increasingly used for extrapolation, or predicting suitable regions for species under new geographic or temporal scenarios. However, SDM predictions may be prone to errors if species are not at equilibrium with climatic conditions in the current range and if training samples are not representative. Here the controversial "Pleistocene rewilding" proposal was used as a novel example to address some of the challenges of extrapolating modeled species-climate relationships outside of current ranges. Climatic suitability for three proposed proxy species (Asian elephant, African cheetah and African lion) was extrapolated to the American southwest and Great Plains using Maxent, a machinelearning species distribution model.

  • "Rewilding North America" by Josh Donlan and 11 other authors, Nature, 18 August 2005 (2 pages).
    Content: The first advocacy article ("commentary") by prominent conservation biologists that proposes "rewilding" close-kin of some of the large mammals that went extinct in North America at the end of the Pleistocene, 13 thousand years ago by reintroducing close relatives or proxies.

  • "Pleistocene Rewilding: An Optimistic Agenda for the 21st Century" by Josh Donlan and 11 other authors, American Naturalist, November 2006, vol 168: pp 660-681.
    Content: This is the long and fully developed version of the 2005 paper, by the same set of authors. Abstract: Large vertebrates are strong interactors in food webs, yet they were lost from most ecosystems after the dispersal of modern humans from Africa and Eurasia. We call for restoration of missing ecological functions and evolutionary potential of lost North American megafauna using extant conspecifics and related taxa. We refer to this restoration as Pleistocene rewilding; it is conceived as carefully managed ecosystem manipulations whereby costs and benefits are objectively addressed on a case-by-case and locality-by-locality basis. Pleistocene rewilding would deliberately promote large, long-lived species over pest and weed assemblages, facilitate the persistence and ecological effectiveness of megafauna on a global scale, and broaden the underlying premise of conservation from managing extinction to encompass restoring ecological and evolutionary processes. Pleis tocene rewilding can begin immediately with species such as Bolson tortoises and feral horses and continue through the coming decades with elephants and Holarctic lions. Our exemplar taxa would con- tribute biological, economic, and cultural benefits to North America. Owners of large tracts of private land in the central and western United States could be the first to implement this restoration. Risks of Pleistocene rewilding include the possibility of altered disease ecol- ogy and associated human health implications, as well as unexpected ecological and sociopolitical consequences of reintroductions. Estab- lishment of programs to monitor suites of species interactions and their consequences for biodiversity and ecosystem health will be a significant challenge. Secure fencing would be a major economic cost, and social challenges will include acceptance of predation as an over- riding natural process and the incorporation of pre-Columbian eco- logical frameworks into conservation strategies.

  • "Pleistocene Rewilding" New York Times Magazine article by Alan Burdick, 12/11/05.
    Content: Summary of one of the NYT's pick-of-the-year best ideas.

  • "Pleistocene Dreams" Orion Magazine, Point of View editorial by Josh Donlan, July 2008.
    A biophilia, soul-centered, and future-generational plea for beginning the bold task of megafaunal Pleistocene Rewilding.

  • "Rewilding Megafauna: Lion and Camels in North America?" an interview with Connie Barlow, by, March 2007.
    Content: Lengthy interview with Connie Barlow discussing the Pleistocene megafaunal rewilding concept. Very useful links to other related articles and audios at the end.

  • Transcript of 11/20/09 Science podcast on on the concurrent paper in the journal, "Pleistocene Megafaunal Collapse, Novel Plant Communities, and Enhanced Fire Regimes in North America" by Jackquelyn L. Gill et al.
    ABSTRACT of paper: Although the North American megafaunal extinctions and the formation of novel plant communities are well-known features of the last deglaciation, the causal relationships between these phenomena are unclear. Using the dung fungus Sporormiella and other paleoecological proxies from Appleman Lake, Indiana, and several New York sites, we established that the megafaunal decline closely preceded enhanced fire regimes and the development of plant communities that have no modern analogs. The loss of keystone megaherbivores may thus have altered ecosystem structure and function by the release of palatable hardwoods from herbivory pressure and by fuel accumulation. Megafaunal populations collapsed from 14,800 to 13,700 years ago, well before the final extinctions and during the Bølling-Allerød warm period. Human impacts remain plausible, but the decline predates Younger Dryas cooling and the extraterrestrial impact event proposed to have occurred 12,900 years ago.

  • "Where the Wild Things Were" by Daniel Cossins in The Scientist, May 2014.
    Survey of ongoing rewilding projects of large animals, mostly in Europe.

  • "Resolving lost herbivore community structure using coprolites of four sympatric moa species" by J.R. Wood et al. in PNAS, Aug 2013.
    ABSTRACT EXCERPT: Knowledge of extinct herbivore community structuring is essential for assessing the wider ecological impacts of Quaternary extinctions and determining appropriate taxon substitutes for rewilding. Here, we demonstrate the potential for coprolite studies to progress beyond single-species diet reconstructions to resolving community-level detail. . . Our results show that moa lack extant ecological analogs, and their extinction represents an irreplaceable loss of function from New Zealand's terrestrial ecosystems.

  • "Pleistocene Dreams" by J. C. Hallman in Seach Magazine, May/June 2008.
    Content: Lengthy report on the author's visits to talk with some of the leaders in Pleistocene Rewilding movement.

  • "Pleistocene Park: Where the Auroxen Roam" by Andrew Curry. 2008. Wired Magazine 16.10
    Content: A long report of the rewilding of Europe's endangered native bison to a 500 acre preserve in Latvia that will also contain other surrogates for Pleistocene megafauna.

  • "Conservation Biology: Reflecting the Past" by Emma Marris, Nature 462, 30-32 (2009)
    Tag line: Unsatisfied with merely halting environmental destruction, some conservationists are trying to reconstruct ecosystems of the past. Emma Marris travels back in time with the rewilders.

  • "Role of Ecological History in Invasive Species Management and Conservation by C. Josh Donlan and Paul S. Martin, Conservation Biology, 1 February 2004
    Conclusion: "Nativeness, place, and history are central to the science, strategies, and aesthetics of biodiversity. Currently, a post-Columbian bias blinds us from a paleoecological view of North America, a vista with widespread policy implications. The attention of the public, long enchanted with dinosaurs, needs to shift to our indigenous Pleistocene patrimony. We lost and cannot replace the Ornithischia. We can resurrect and along the way help save the Proboscidea."

  • "Resurrecting Extinct Interactions with Extant Substitutes" by Christine J. Griffiths et al., Current Biology 21(8), April 26, 2011
    Summary: Rewilding with taxon substitutes, the intentional introduction of exotic species to replace the ecosystem functions of recently extinct species, is one way to reverse ecosystem dysfunction following the loss of species interactions [2]. This is highly controversial [3], in part because of a lack of rigorous scientific studies [4]. Here we present the first empirical evidence of an in situ rewilding project undertaken as a hypothesis-driven ecosystem management option. On Ile aux Aigrettes, a 25-hectare island off Mauritius, the critically endangered large-fruited endemic ebony, Diospyros egrettarum (Ebenaceae), was seed-dispersal limited after the extinction of all native large-bodied frugivores, including giant tortoises. We introduced exotic Aldabra giant tortoises, Aldabrachelys gigantea, to disperse the ebony seeds. Not only did the tortoises ingest the large fruits and disperse substantial numbers of ebony seeds, but tortoise gut passage also improved seed germination, leading to the widespread, successful establishment of new ebony seedlings. Our results demonstrate that the introduction of these exotic frugivores is aiding the recovery of ebonies. We argue for more reversible rewilding experiments to investigate whether extinct species interactions can be restored.
       See also: authors' press release; BBC News Online; Mail Online (UK); Discovery News.

  • "On the Use of Taxon Substitutes in Rewilding Projects on Islands" by Dennis M. Hansen, Islands and Evolution, 2010, 33 pages in PDF.
    In-depth survey of the most advanced on-the-ground example of "rewilding" that has occurred to date, written by one of the principal scientists leading the effort. Hansen writes, "I believe islands offer some of the best-suited scenarios to rapidly advance our empirical understanding of rewilding and exploring the use of taxon substitutions in conservation and restoration."

  • "The Use of Extant Non-Indigenous Tortoises as a Restoration Tool to Replace Extinct Ecosystem Engineers" by Christine J Griffiths et al, Restoration Ecology, 2010.
    Content: We argue that the introduction of non-native extant tortoises as ecological replacements for extinct giant tortoises is a realistic restoration management scheme, which is easy to implement. We discuss how the recent extinctions of endemic giant Cylindraspis tortoises on the Mascarene Islands have left a legacy of ecosystem dysfunction threatening the remnants of native biota, focusing on the island of Mauritius because this is where most has been inferred about plant-tortoise interactions. There is a pressing need to restore and preserve several Mauritian habitats and plant communities that suffer from ecosystem dysfunction.

  • "Rodrigues Island: Hope thrives at the Franois Leguat Giant Tortoise and Cave Reserve" by David A. Burney, Madagascar Conservation and Development, June 2011.
    2-pages illustrated review of a tortoise restoration project on the island of Rodgrigues, and how the tortoises are helping to restore highly endangered native plants.

  • "Conservation and restoration of plant-animal mutualisms on oceanic islands" by Christopher N. Kaiser-Bunbury et al, Perspectives in Plant Ecology, Evolution and Systematics, 2010.
    13 pages, with color illustrations, on island restoration and rewilding efforts focusing on using congenerics or other species proxies where extinctions preclude restoring historically native species with whom extant native plants coevolved.

  • "Seed Dispersal and Establishment of Endangered Plants" on Oceanic Islands and the Use of Ecological Analogues", www.PLOSone, by Dennis M. Hanson et. al, May 2008.
    Content: Meshes "ecological anachronisms," conservation biology, rewilding of ecological proxies/analogs, and assisted migration/colonization, in a landmark paper that experimentally demonstrates the ecological viability and conservation value of introducing Aldabran tortoises to the oceanic island of Mauritius as ecological proxies (seed-dispersal agents) for Mauritian tortoises that were driven into extinction by humans.

  • "Rewilding Megafauna: Lions and Camels in North America?" interview with Connie Barlow, March 2007.
    Content: in-depth interview on Pleistocene Rewilding: its conservation potential and ethical and ecological justifications.

  • "Rewilding America, Pleistocene Style" The Monitor's View, Christian Science Monitor, 30 August 2005.
    Content: Editorial generally supportive of the August 2005 paper in Nature.

  • "Should Humans Give 'Hot' Animals a Hand?" by staff, Daily Democrat (Woodland, CA), 24 January 2007.
    Content: Lots of quotes from Dr. Mark Schwartz on the assisted migration issue.

  • "Restoring America's Big, Wild Animals" by Josh Donlan, Scientific American, June 2007.
    Lead author of the "Pleistocene Rewilding" paper originally published in Nature writes for a popular audience and responds to criticism that has emerged.

  • "Bring Elephants to Australia?" by David Bowman, Nature, 2 February 2012.
    Proposes introducing elephants and bringing back a proxy (Komodo dragon) for a giant extinct lizard in an effort to control rampant wildfires energized by alien grasses and alien predators of native marsupials. For excellent commentary and background on this paper, see: Australia's Newest Firefighters: Elephants?" by Nidhi Subbaraman.

  • "Big Animal Extinction 'severed nutrient arteries'" by Mark Kinver, BBC News, 12 August 2013.
    "The demise of big animals in the Amazon region 12,000 years ago cut a key way that nutrients were distributed across the landscape, a study has suggested. Researchers say animals such as huge armadillo-like creatures would have distributed vital nutrients for plants via their dung and bodies."

  • "Bringing Back Europe's Prehistoric Beasts" by Jens-Christian Svenning, Scientific, June 2007.
    Proposes rewilding the endangered Asiatic lion into Europe.

  • "Pleistocene Rewilding" webpages
    Ongoing reports, news articles, and blog entries on this topic, posted at the The Rewilding Institute website.

  • "Pleistocene Rewilding" WIKIPEDIA entry
    Wikipedia entry, with photos and references, on this topic.

  • "The North Atlantic Ocean: Need for Proactive Management", by John C. Briggs. Fisheries, April 2008. Vol 33, pp. 180-184.
    For those of us considering the importance of "assisted migration" of species impacted by climate change, or outright "rewilding" of species or surrogates to regions in which they lived thousands of years ago, this paper is something to ponder. Here the author proposes that the collapses of fisheries in the North Atlantic may be irreversible without infusion of new species diversity, and that much is to be gained (and little risked) by introducing North Pacific fishes into the North Atlantic. The deep-time discussion of "The Great Trans-Arctic [Marine] Biotic Interchange" (which began 3.5 million years ago when the Bering Land Bridge was transgressed by marine waters), is crucial reading for those of us working with entirely terrestrial biotas.

  • "Rewilding Megafauna: Lions and Camels in North America?" Interview with Connie Barlow
    Interview published on the Action Bioscience website, an education resource of the American Institute of Biological Science

  • "Cloning Mammoths for Pleistocene Rewilding" blogpost
    Useful blogpost and comments on the possibility of cloning frozen mammoth DNA from flesh or sperm.

  • "Michael Archer: How we'll resurrect the gastric brooding frog, the Tasmanian Tiger"
    17-minute video from the TEDx "De-Extinction" series of talks, 2013.

  • "George Monbiot: For more wonder, rewild the world"
    15-minute video from TEDx, featuring the ecological benefits of bringing wolves back to Yellowstone, and advocacy for bringing back the extinct megafauna and how plants alive today in Europe seem adapted to elephants and rhinoceros. "Rewilding offers us the hope that our silent spring could be replaced by a raucous summer." And from an online essay: "Understorey trees such as holly, box and yew have much tougher roots and branches than canopy trees, despite carrying less weight. Our trees, in other words, bear strong signs of adaptation to elephants. Blackthorn, which possesses very long spines, seems over-engineered to deter browsing by deer; but not, perhaps, rhinoceros."

  • "Doom of the elephant-dependent trees in a Congo tropical forest"
    2013 paper by David Beaune et al, published in Forest Ecology and Management. On how extirpation of forest elephants in the Congo is diminishing or eliminating seed dispersal of forest trees have fruits that evidence the "megafaunal dispersal syndrome."

    Click here for Proposed Standards for Assisted Migration of Plants.

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