Rewilding Torreya taxifolia
to Lake Junaluska, North Carolina
July 2008

10 potted seedlings to Corneille Bryan Native Garden


   NE-facing slope of a NW-to-SE ravine with perennial creek at the bottom (2,600 feet elevation).

The uppermost canopy is almost entirely deciduous, thus affording sun for Torreya's evergreen growth in early spring, late fall, and mild winters.

DOCUMENTATION and analysis by Connie Barlow.


RESULTS TEN YEARS LATER - 2018

• Two growing in deciduous shade are healthy: adopted horizontal growth form
• Two planted in full sun are healthy: adopted vertical growth form
• Six of the ten were killed by rodents eating stem cambium and/or roots
Note: The planted seedlings were given names rather than numbers. Click names for a detailed, photo-rich page of each.

   William Bartram
Rachel Carson

Hazel Delcourt
Henry David Thoreau

Lucy Braun
Wangari Maathai
Aldo Leopold

Chauncy Beadle
Hardy Croom
Asa Gray


TABLE OF CONTENTS - Click ahead for

CHALLENGES

HORIZONTAL GROWTH FORM

VERTICAL GROWTH FORM

LEARNINGS



CHALLENGES:

1. ROOTBOUND & CROWDED. The potted seedlings were very healthy, but root-bound. They had been too long in the pot and required time to grow roots outward and to readjust their branch orientation to uncrowded and shadier conditions than they had at their nursery in South Carolina. (Lee Barnes and Russ Regnery planting seedlings in center photo above.)
     Outplanting into natural forest thus required initial watering by chief gardener Janet Manning. In the photo above right she is holding the sign for just-planted Lucy Braun seedling (orange flag marker).

2. RODENT HERBIVORY. Three of the ten plantings perished during their first winter, owing to rodents eating the bark and root cambium. Photos above were taken by Lee Barnes spring 2009. He discovered and interpreted the casualties of Chauncey Beadle, Hardy Croom, and Asa Gray. Immediately, Janet Manning outfitted the remaining seedlings with wire cages at their base.

Seven years later, Connie Barlow made a site visit (May 2016) and discovered that tunneling, root-eating rodents had killed over winter two previously very healthy torreyas: Lucy Braun and Wangari Maathai. The photos above are the remains of Wangari Maathai — including the wire cage that did indeed protect the above-ground stem, but not the roots.
     Below is what Wangari Maathai looked like in April 2015 — one year before her death (when Connie Barlow and Jim Thomson made a site visit). Notice that what had been a basal stem was now as tall as the original main stem. The shady site induced Wangari to spread horizontally, becoming multi-stemmed while seeking sunlight. The chart alongside shows that vegetative bud-counting began on the 2013 visit, continued in 2015. Connie gave up the practice in 2016, owing to the discovery that vegetative buds had begun emerging not only on branch tips but also on inner (older) segments of the branches themselves.

   PHOTO LEFT: Michael Dowd marks the planting of Chauncey Beadle in 2008. Notice the house in the picture.

ROOT-EATING RODENT HYPOTHESIS - Of the original 10 plantings in 2008, only 4 remained in 2018. All 6 deaths are attributable to tunneling, root-eating rodents. Because the same-age, same genetics set of 21 Torreya plantings at the Waynesville site had not been afflicted in the same way, the rodent problem must be site-specific.

The forest garden (Corneille Bryan) is surrounded by pavement and homes, and there are two sources of boom-and-bust foods: (a) the Red and White Oaks have multi-year cycles of acorn masting, and (b) the house in the southwest corner of the garden forest (shown here) has a birdfeeder overhanging its deck that drops seed only during this seasonally occupied summer community.

3. RHODODENDRON ENCROACHMENT. Look carefully at the photos of Rachel Carson, below, in 2012. A large rhododendron is easy to see to the right of Lee Barnes (partly blocking his shirt). There is also a rhododenron to the left, easily seen in the top-down view of Rachel in the right photograph. The light-green rhodie leaves just inches away indicate spring growth.

Because rhododendrons are not only evergreen but also tend to produce an impenetrable monoculture (no other species beneath them), the LESSON here is that it is a good idea to PLANT TORREYA ONLY WHERE RHODODENDRON (and laurels) ARE ABSENT for a good long distance. It will be up to garden management to make the call whether and when to prune back the rhodies. Either way, there are lessons to be learned by continuing observations in the years ahead.

4. TREEFALLS. The photos above show William Bartram in 2015 (left) and 2018 (right). In the left photo, the big tree is a Red Oak, but the small ones at the top slope left (a paved road and homes are just beyond them) are hemlock trees. The biggest hemlocks are being treated with pesticides, but the young hemlocks were untreated, and thus were killed by the woolly adelgid. On a site visit October 2018, two dead trees had fallen, barely missing Bartram's large basal stem (which had been vertical in 2016 but is now leaning). The original, greatly leaning stem has gone missing. (A light-colored segment of old cement curb is visible center-up; it was there at the 2008 initial planting and has been an easy marker for finding William.)
     Note: In 2018 Connie Barlow also made a site visit to the Waynesville planting; a free-planted seedling there had its stem pushed onto the ground by a 2-inch-wide fallen branch. Two years of reoriented growth were visible, thus putting the new growth 90 degrees from the orientation of the ground-laying stem (which popped back up skyward when the branch was removed).
    LESSON: As with other subcanopy trees (like Umbrella Magnolia and American Beech), Torreya can easily reorient growth skyward, so long as the roots are sound and crucial parts of the plant can access sunlight.

SUMMARY OF CHALLENGES. Overall, because THE SITE ITSELF HAS PROVEN FAVORABLE FOR TORREYA, any difficulties and deaths can be attributed to specific causes other than climate, aspect, soil type, etc. Careful siting can eliminate the danger of rhododendron encroachment (at least for several decades), but nothing can eliminate the possibility of future branch and treefall in a forested setting.
    

 

  PHOTOS OF JULY 2008 PLANTINGS OF ALL THE RODENT-KILLED SEEDLINGS: Left column shows Chauncy Beadle, Hardy Croom, and Asa Gray — all killed the winter of 2008/09. Second column shows Lucy Braun, Wangari Maathai, and Aldo Leopold — all killed the winter of 2015/16.

By far the biggest danger is RODENT HERBIVORY in the early years. Seeds directly planted into forest soil are extremely vulnerable to squirrels and voles — unless planted more than 3 inches deep (or under a rock). First- and second-year seedlings resulting from "free-planting" of seeds directly into forest habitats are vulnerable to herbivore nipping of apex buds; seedlings are less vulnerable once the first lateral branches appear and harden. For possibly a decade (or more) the lower stems (before thick bark develops) and the roots remain vulnerable to small and tunneling rodent herbivory (presumably during the winter). Choosing forested sites nowhere near BIRDFEEDERS may be helpful in reducing the instances of rodent cycles of overpopulation.

VISIT our PROPAGATION WEBPAGE for details and suggestions on how to reduce rodent herbivory and other problems. For example, it is crucial to ensure that the soil surrounding the roots is no more attractive to rodents than the forest soil in general (so shake out the soil from potted plants before planting). Another idea (not yet tested) is to add gravel to the hole and the surrounding soil when putting in a plant. Overall, consider easy ways to naturally deter rodents that do not require continued surveillance (or later removal of wire barriers).


HORIZONTAL GROWTH FORM: William Bartram and Rachel Carson

Of the four surviving trees in 2018, two have a vertical growth form and two have adapted for horizontal growth.

• VERTICAL GROWTH is the adaptation if humans have put them (and maintained them) in sunny locations.

• HORIZONTAL GROWTH signifies that sunlight is dappled through a canopy, and thus lateral spread will capture more sunlight than will growth of the apical leader.

 

ABOVE: The locations where BARTRAM and CARSON were planted stimulated horizontal growth. That's a white cement curb near Bartram, presumably fallen from the paved neighborhood road upslope. A Red Oak is upslope (west) from Rachel

BELOW: Mid-May 2012, Lee Barnes and Connie Barlow made a site visit. Lee is using a grid to document growth of WILLIAM BARTRAM (both left and right). Two stems are easily visible in the left photo. For the right closeup, look carefully off the numbered right side of the grid to see the terminal leader reaching up to 17 inches. The light-green growth of the branchlets signify a lot of healthy new lateral growth freshly emerged by late spring.

 

ABOVE LEFT: The two horizontal growers are just a dozen feet from one another. Notice RACHEL CARSON showing a lot of vibrant new growth at lower left of the left-most photo. And notice a large Rhododendron between the two. Because this photo was taken across slope in a southwesterly direction, the evergreen rhodie is already blocking some late-fall and early-spring sun that would otherwise reach Rachel beneath this deciduous canopy.

 

ABOVE LEFT: Late April 2015, and the Red Oak overtopping RACHEL is still not leafed out. Spring beneath an oak is a good time for subcanopy growth.

ABOVE RIGHT: Late April 2013 shows a lot of sun on WILLIAM. This is also a good view of the standard, two-stemmed horizontal growth form: The thick, original stem is leaning far to the right, while still putting on a lot of lateral growth. Meanwhile, the younger basal is still exploring opportunities skyward. (Michael Dowd in the photo.)

SUMMARY OF LESSONS - HORIZONTAL GROWTH FORM. Genus Torreya is a subcanopy tree species. When a canopy opening occurs (of if humans plant in locales of full sunlight, like a maintained lawn or along a roadside) Torreya may be inclined to shift to a vertical growth form (see below). But even then, the genus tends not to exceed 60 feet in height. Thus under wild conditions, canopy natives (like oaks and tuliptrees and buckeyes) would eventually overtop the long-lived Torreya once again. As well, squirrel dispersal of seeds will likely place next generations under a subcanopy. Thus the horizontal growth form is the most likely growth form under natural conditions in most locales and during most time increments of the long life-span of species in genus Torreya. (See the natural history of Torreya page on this website.) Thus Connie Barlow recommends that it is crucial to:

STUDY THE HORIZONTAL GROWTH FORM under natural conditions in the eastern USA paleo-range of genus Torreya — that is, under a deciduous canopy. Except for the problem of encroachment of evergreen Rhododendron, continuing pictorial documentation of the two surviving horizontal specimens at Lake Junaluska will offer insights into healthy horizontal growth patterns and cycles. In contrast, recurring stem dieback and basal growth in the historically native range (peak glacial) of Florida Torreya obscures this opportunity because, as a "glacial relict" that was "left behind" when the Ice Age waned, genus Torreya is now beset with stem diseases when regrowing from old rootstock in Florida. Lethal stem diseases are not evident at any of the Torreya Guardian plantings or documented historic sites in the southern Appalachians.


VERTICAL GROWTH FORM: Hazel Delcourt and Henry David Thoreau

Text and photos to be added.


SITE-SPECIFIC LEARNINGS (as of 2018)

The Lake Junaluska locale offers insights for helping species recovery ...

1. ASSISTED MIGRATION - The plants seem to be disease-free at this latitude and elevation some 300 miles north of the historically native range in Florida.

2. ADAPTIVE GROWTH FORMS - If afforded the opportunity to grow in open sunlight, Torreya takes the form of a standard conifer (HAZEL DELCOURT and HENRY DAVID THOREAU). If the habitat is shaded subcanopy, its form is yew-like and growth is much slower (RACHEL CARSON and WILLIAM BARTRAM). Because Torreya genus is not a pioneer-sere taxon, only human intervention in cutting back overgrowth shade can maximize Torreya's growth potential and induce an upright form (and early seed production). As of 2018, no reproductive structures have been observed on even the tallest individuals (HAZEL DELCOURT and HENRY DAVID THOREAU).

3. ROOT-EATING RODENTS - Of the original 10 plantings in 2008, only 4 remain in 2018. All 6 deaths are attributable to tunneling, root-eating rodents. Because the same-age, same genetics Torreya planting at the Waynesville site has not been afflicted in the same way, the rodent problem must be site-specific. The forest garden (Corneille Bryan) is surrounded by pavement and homes, and there are two sources of boom-and-bust foods: (a) the Red and White Oaks have multi-year cycles of acorn masting, and (b) the house in the southwest corner of the garden forest has a birdfeeder overhanging its deck that drops seed only during this seasonally occupied summer community.

4. COMPETITIVE EXCLUSION BY RHODODENDRONS - Rhododendrons and Mountain Laurels are evergreen, subcanopy shrubs. Rhodies easily outpace Torreyas. (RACHEL and WILLIAM both have rhodies encroaching.)

5. REWILDING CONSTRAINTS - Unlike animals, plants cannot move to situate themselves in ideal circumstances — so we planters must attempt to find those macro sites (latitude, elevation, slope, aspect, forest type) and micro sites: rhododendron-free, deciduous canopy, extreme slopes. Until hundreds of seeds or seedlings are available for outplanting in each area, human interventions will remain necessary for ensuring speedy development of reproductive populations.
    ACTIONS include: wire cages against surface rodents, removal of encroaching Rhododendrons, prompt removal of branch and treefalls. Autumn protection from antler rubbing will be important in deer habitat when a seedling reaches a height of 2 or 3 feet and until the prickly-leaf sapling loses its low branches. (Our planting site at Lake Junaluska shows no evidence of deer herbivory.) Both to deter deer and tunneling rodents, siting plants on extremely steep slopes is advised.
    IDEALLY, in every "rewilding" site (distinct from full-sun, tended "orchard" sites), specimens should be numerous enough to have some managed for nearly full sunlight, some placed beneath a deciduous canopy but managed against branch-fall and rhodie intrusion, and others planted in various settings and left largely unmanaged — thus affording opportunities for learning more of Florida Torreya's natural history, preferences, and abilities to withstand and recover from setbacks. Visit the
Propagate page for details.


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