What We Are Learning
• Torreya's Habitat Preferences
• Best Practices for Recovery
• Adaptive Growth Forms
Ongoing Report by
Torreya Guardian founder, Connie Barlow
Contact: conniebarlow52 at gmail dot com
Learnings are chronologically organized, from the most recent • Visit our Reports page for more accomplishments
• April 2019: Proof that cutting of basal leader tip yields tree-form Torreya
April 24 email from Clint Bancroft (Torreya planter in Ocoee watershed of Tennessee) to Connie Barlow:"Look at the new growth on this cutting from Highlands, NC! The cutting is the apical tip from a basal of one of the mature trees."Photo left, by Clint Bancroft, is April 2019 of a rooted cutting (collected October 2017) that displays superb vertical growth. Photo right is by Connie Barlow 2006, during a Torreya Guardians site visit to the near-century old Highlands NC Torreya grove. Notice the prolific basal sprouting, of various ages.
LEARNING: The original cuttings of wild specimens in the Florida panhandle were collected three decades ago from branches that necessarily assume shrubby growth forms. Wild stock was so weak that cutting of basal terminals would not have been appropriate. However, when collecting vegetative growth from healthy horticultural plantings in northward states, we now know that apical growth of basals are essential for ultimately producing tree forms.
• MARCH 2019: "Endangerment Causes" webpage expanded for scholars
This LEARNINGS webpage features site-specific discoveries and documentation in the field. However, this particular entry is a distillation of the scholarship and argumentation pro and con assisted migration of Florida Torreya specifically and the much larger and wider debate on assisted migration as a climate adaptation tool, even for common native species, that has been playing out in scientific journals and news media.
The "Endangered (causes of)" webpage has been online (and periodically updated) for more than a dozen years. However, in 2019 it seemed time to reconfigure the text for ease of use and to distinguish the background, objective summaries (with key links) from Torreya Guardians advocacy sections.
Two events in 2018 indicated a reconfiguration was in order: In March 2018, genetic engineering of the Torreya genome was advocated by a University of Florida forest pathologist. And in August of 2018 the U.S. Fish & Wildlife Service announced that the 2010 recovery plan would be updated in 2019.
Annotated access to key documents is sectioned into six parts (image left).
• JANUARY 2019: First Herbivory-Free Site is Video-Documented
Site visit by Connie Barlow to Shoal Sanctuary, due west of Torreya's peak glacial refuge in northern Florida. Documentation of 9 seedlings thriving (and remarkably free of herbivory) four years after 40 seeds were placed directly into the coolest, moistest habitats. Microsite distinctions portend excellent learnings in the years ahead.
This last half of the video set summarizes the documentation and offers topics for further study notably, why herbivory was absent at all planting sites. Native Christmas Ferns are pointed out as ideal neighbors for (1) camouflage, (2) its "endo" mycorrhizal network, and (3) as an "indicator species" for identifying best microsites for Torreya.
2018 SUMMARIES of Evidence that Clear Way for Assisted Migration
Throughout the past 14 years, Torreya Guardians have site-visited and photo-documented horticultural plantings of Florida Torreya in northward states that are at least 50 years old. Because the 2010 official recovery plan will be updated in 2019, Connie Barlow aggregated what these groves teach us onto a new webpage:
• 2018: Historic Groves of Torreya Trees: Long-Term Experiments in Assisted Migration
Field examinations of historic groves of Torreya taxifolia planted north of its peak glacial range in Florida confirm that
(1) Torreya can thrive and naturalize in northward states.
(2) It will not become invasive if assisted to migrate north.
Lack of documentation establishing the combination of thrival and non-invasiveness were the key obstacles to adding an assisted migration action to the management plan for Florida Torreya during the plan update in 2010. The advisor whose written statement included an objection to northward experimentation is listed as Ms. Tova Spector (Florida Park Service). Her objection is quoted on p. 25 of the 2010 Recovery Plan Update. She stated:The reason for not moving Torreya taxifolia outside of its range was addressed by Schwartz (2005). Moving Torreya outside of its range would alter the natural community where it is introduced. In addition the species may be susceptible to decline from factors in the introduced location. Instead trees should be safeguarded in botanical collections until the causal agent(s) for its decline can be mitigated in its historical range.... The author [Mark Schwartz] also stated that, "if assisted migration is going to be used sparingly, and only in conditions where the need is dire, then the conservation community should begin now to specify and advertise a consensus view on when this may be appropriate." As I stated in this document, before an emergency plan is implemented, guidelines should be developed.
• 2018 Summary of Academic Papers Trending Toward Assisted Migration
Much has been learned in the eight years following the 2010 plan update, including:
(a) ACADEMIC PAPERS ON ASSISTED MIGRATION. Prof. Mark Schwartz, whose 2005 paper was listed in the above quotation as the scientific basis for not authorizing an assisted migration experiment in the 2010 plan update, became lead author in 2012 of a 31 co-author paper that established guidelines for assessing the risks (including non-thrival and possible invasiveness) prior to conducting "managed relocation" of a climate-challenged species. And in 2009 he was coauthor of a 22-author paper, "Multidimensional Evaluation of Managed Relocation", the data supplement of which applies an evaluative framework to three case studies, the second of which is Case 2: "Translocating Torreya taxifolia to the Southern Appalachians". That 2009 case study, combined with the 2018 compilation of Historic Groves documentation by Torreya Guardians, offer a combination of field evidence and academic evaluation supportive of assisted migration for this left-behind glacial relict species. Heightened scientific projections of the magnitude and rate of ongoing climate change (IPCC 2018 report) should also play a role in the 2019 recovery plan update, as should the positive attention afforded assisted migration in parks management reported in the Jan-Feb 2019 issue of Sierra Magazine and its inclusion in chapters 7 and 28 of our nation's Fourth National Climate Assessment, November 2018. As well, a 42-coauthor review paper published in 2018 can help advisors and decision-makers put Florida Torreya considerations within the context of leading-edge academic understandings at the global scale: "REVIEW PAPER: Managing consequences of climate-driven species redistribution requires integration of ecology, conservation and social science.
(b) TORREYA SEEDS CANNOT BE STORED. Torreya's seed is recalcitrant and cannot be stored except via cryo-preservation following laboratory manipulation of tissue culture via "somatic embryogenesis". The thousands of seeds currently being produced ex situ must therefore be used for plantings or will be lost. They cannot be inexpensively stored. Also in 2018, a paper published in Nature Plants confirmed that a large proportion of plants (especially endangered plants and notably trees) have recalcitrant seeds that cannot be stored: "Seed banking not an option for many threatened plants".
(c) ASSISTED MIGRATION AS MODERATE COMPARED TO GENETIC ENGINEERING. All attempts to ensure Torreya survival in the soil and other conditions within the geographic boundaries of Torreya's native Florida range have failed. In 2018 genetic engineering of the genome was offered to infuse disease resistance. Authorizing assisted migration experiments would be a moderate next step compared to moving forward with genetic manipulation.
(d) Forestry researchers have charted the way for assisting the poleward movement of tree species and genetically distinct populations of trees during what is now widely acknowledged as a century of climate change far more rapid than seeds of many species can disperse. Conservation biologists can quickly access the key forestry research papers on assisted migration to ensure that their own understandings are congruent with the imperatives of climate change adaptation, as pioneered by forestry researchers who compute how climate projections will affect range shifts of America's native trees species.
• 2018 Documentation: Free-Planting Torreya Seeds directly into forest habitats
A NEW WEBPAGE of LEARNINGS by Torreya Guardians (posted December 2018) may assist the recovery of Torreya taxifolia in a very practical way: Assisted migration experiments can be implemented inexpensively:
More than a half-dozen Torreya Guardians began experimenting (as early as 2011) with "free-planting" seeds directly into their ultimate within-forest destinations. This new technique bypasses the labor-intensive, bulky, and potentially costly initial phase of poleward plantings that germinates seeds in pots or wire-protected soil beds prior to final planting (which, again, has often included wire cages for each specimen). In 2018 results were aggregated into a new photo-rich webpage, which will be updated ongoingly.
Results are presented in topical sections:
• Risks and Advantages of Free-Planting
• Learnings 1: Seed Harvesting, Storage, Germination
• Learnings 2: Techniques To Deter Seed Predators
• Learnings 3: Torreya Recovers from Herbivory
• Learnings 4: Siting to Minimize Above-Ground Herbivory
• Learnings 5: Siting to Minimize Antler Rubbing
• Learnings 6: Siting for Myccorrhizal Connections
• Learnings 7: Natural Seedlings in Historic Groves
Field documentation of the 6 seedlings that grew and survived with no human help, following "free-planting" of 15 seeds directly into forest soil in April 2015. Russ Regnery was the planter, within his forest at 3,800 feet elevation on the slope of Black Rock Mountain, near Franklin NC. Video clips of the 2015 planting (Episode 12) are matched with the actual seedlings closely photographed and analyzed Nov 2018. Results: Four summers later, this species exhibits remarkable capacities to recover from early stem and leaf herbivory.
Free-planting experiments have ranged from projects of just 6 seeds to 400 seeds. Our 400-seed planting family, Chris and Christina Anderson (Spring City, TN) have become our foremost example of how free-planting can be done quickly, inexpensively, and well documented (flagged) to facilitate year-by-year appraisals of results:
November 2015 Chris and Christina Anderson planted 400 seeds over the course of two days in several sections of their 232 acres on an eastern ridge of the Cumberland Plateau.
All planting sites were marked with colored flags, using best practices: placing a rock atop each seed or planting 3 inches (or more) deep.
Most seeds were planted within two ravines (visible at the SW and NE edges of the bounded red section shown on this map. Some were also planted along the firebreak jeep trail in the uplands, as these sites can regularly be checked without walking off-trail.
Canopy cover where plantings occurred are mostly deciduous, with some old hemlock groves in the deepest ravine.
First seedlings were observed August and September of 2017. Chris Anderson guided Connie Barlow (and her video camera) on a site visit November 2017:
VIDEO 24: Florida Torreya to Cumberland Plateau - Rewilding an Endangered Tree
By far the most expansive and exciting experiment in "rewilding" Torreya taxifolia into northward states began in November 2015 on the Cumberland Plateau of Tennessee. All 400 seeds were "free-planted" directly into the ground either 3 inches deep or under rocks to protect the seed from rodent predation. Two years later, Connie Barlow video-documented the beginning success of 38 new seedlings.
• 2018: FREE-PLANTING LEARNINGS USED TO UPDATE INSTRUCTIONS TO PLANTERS
Our webpage of ADVICE FOR PROPAGATING TORREYA has been updated to offer clear advice of Best Practices for Free-Planting Seeds:1. TO DETER SEED PREDATION: Plant seeds at least 3 inches deep (4 to 6 inches may be best). Flat rocks placed over a seed may also help, but the dangers of rocks are that they attract ants, may prevent the seed from accessing rain, and may force the germinating stem to circle around before finding a way to pop out the side (usually upslope). See PHOTOS of good and bad results at this section of our detailed free-planting webpage.
2. TO DETER ABOVE-GROUND HERBIVORY: Newly emerged stems and leaves are vulnerable to toothed herbivores upon emergence. Even when the needle-like leaf tips harden, deer and rodents may still nibble and sample. As a subcanopy-adapted tree, Torreya is usually capable of regrowing again and again, very quickly adding extra vertical stems (as well as regrowing lateral branches) so that the little seedling becomes less and less vulnerable to herbivory as the years pass. (See photos of herbivory recovery on our free-planting webpage.) As of 2019, we have several siting recommendations for free-planted seeds that are not given any wire protection upon germination:
2A. PLANT SEEDS WHERE DEER ARE LEAST LIKELY TO VENTURE: Possibilities include a deep densely vegetated ravine and the steepest slope you can find. Possibly within the thicket of branches of a recent treefall.
2B. PLANT SEEDS WITHIN THE OUTER REACH OF EVERGREEN FERNS. Fall of 2018, three locations documented that the only free-planted individuals that had escaped above-ground herbivory after three or more years were camouflaged during the winter by evergreen fern fronds. One of the three examples is shown in photos below.
♦ FIND THE TORREYA IN THE PHOTO DIRECTLY BELOW:
The Torreya LEFT has the same camera angle as the photo ABOVE, so you can definitely find it on your own. This perfect little seedling showed no sign of herbivory. (December 2018)
This rural area of NE Alabama is a patchwork of cattle grazing and other fields, regrowth forest, and routine logging. Deer are not abundant and certainly not overpopulated here. But prints do turn up regularly in muddy sections of this forest.
This was the only one of 13 emerged seedlings camouflaged by Christmas fern fronds and it was the only one not damaged by herbivory.
• 2018: DOCUMENTATION OF ADAPTIVE GROWTH FORMS (10 YEAR RESULTS)
UPDATED WEBPAGE: The Lake Junaluska locale in North Carolina (planted with 10 potted seedlings in 2008) offers insights for helping endangered species recovery ten years later. ADAPTIVE GROWTH FORMS is one of the key insights:ADAPTIVE GROWTH FORMS - If afforded the opportunity to grow in open sunlight, Torreya takes the form of a standard conifer. If the habitat is shaded subcanopy, its form is yew-like and growth is much slower. 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.1. HORIZONTAL V. VERTICAL GROWTH FORMS:
VIDEO 29: Florida Torreya to Lake Junaluska NC - 2018 update
Ten years after the 2008 planting of ten potted seedlings as a first "assisted migration" project (reported on by Audubon Magazine), Connie Barlow returns to document ongoing results. The challenges, the successes, and the learnings are all topics covered here and also on the Lake Junaluska webpage.
A key learning is how Torreya is capable of adapting its growth form to conditions of shade (horizontal, yew-like form) or abundant sunlight (standard conifer form).
2. LONG, GROUND-LYING BRANCH ADAPTATION:
Autumn 2018 Torreya Guardians Clint Bancroft and Connie Barlow visited 3 mature Florida Torreyas planted 68 years ago at DORMON NATURE PRESERVE in north-central Louisiana.
PHOTO LEFT: At Louisiana's Dormon Preserve, Torreya Guardians photo-documented the third example of the ground-trending, long-branch growth form that we had documented previously at two North Carolina sites of near-century-old groves.
Note: The photo left appears on the new in 2018 Louisiana Torreya webpage. Barlow also captured video footage during the site visit, published on youtube as a 70-minute VIDEO in two parts (episode 30) "Florida Torreya in Louisiana - Mature Grove with Seedlings".
One hypothesis for the conditions that trigger this growth form is that a torreya tree that begins its life in open sunlight (and thus assumes a vertical-trending, conical conifer form), has a back-up adaptation if and when fast-growing species of trees close in and begin to overtop it. That growth form is this:GROWTH FORM ADAPTATION TO OVERTOPPING: One (or more) of Torreya's lower branches on the sunniest side, usually south-facing, and which emerge no more than 3 feet above ground on the main stem, will reestablish fast horizontal growth. The branches will be supported by the ground in their quest to reach sunlight. When direct sunlight is accessed, the branch thickly fills out leaves and branchlets to maximize solar collection. Branch lengths easily reach out 20 or 30 feet distance from the main stem, while the thickness of the branch at trunk emergence remains uncharacteristically thin, thanks to ground-level support.The photos below show the same ground-lying branch form at two other mature groves:
3. FULL EXPOSURE PRODUCES DENSE FORM (and COLD CLIMATE HIDDEN SEEDS)
While more photos and comparisons are needed, it is becoming apparent that in full-exposure sites, Florida Torreya assumes a much denser growth form than when in shady, inner forest sites. Two photos immediately below show dense growth forms in New York (below left) and also in North Carolina (below right).
ABOVE LEFT (NY): Famed botanist H.W. Sargent wrote a supplement to Treatise on the Theory and Practice of Landscape Gardening, by A.J. Downing, 6th edition published in 1859. This Torreya taxifolia specimen is attributed to Sargent's own property at his home in Beacon, NY. Peter Del Tredici (pers comm. 2019) wrote, "It might be the first image of a cultivated specimen of the tree." Its caption reads: "Torreya taxifolia, at Wodenethe, Age, 6 years. Height, 8 feet. Circumference 20 ft."
ABOVE RIGHT (NC): East of the mountains of North Carolina is Mt. Olive, home of A.J. Bullard, well known botanical naturalist. Here he stands in front of 2 specimens he planted at his home (photo October 2013 by Connie Barlow). See photo-essay of Mt. Olive torreyas.
BELOW (OH): The three fully exposed Florida Torreya trees at the home of Fred Bess near Cleveland OH exemplify the dense form. Biting winter winds, of course, killed the north windward side leaves when the protected potted seedlings were first planted out. But new growth adapted. Periodic branchlet diebacks in extreme winter conditions naturally "prune" the trees into even denser forms.
Most interesting is that the seeds all seem to be at wind-protected inner locations on the south side of the tree (see photos immediately below in October 2018 section). Because the female reproductive structures are pollinated during one growth season and must survive a full winter before ripening autumn of the following year, it is possible that the reason for the inner location of seeds is that nascent seeds on the outer branches are generally killed during the winter.
Or, possibly, the tree simply installs its female structures at greater depth than it does in warmer climes. More observations will be helpful.
PHOTOS BELOW show Fred Bess and Connie Barlow search for seeds within the inner depths on the south side of the female tree. (Female tree is far right in the photo above.) All photos taken October 2018.
• October 2018: Cleveland OHIO seed-grown Torreya female produces 19 seeds
Connie Barlow and owner-grower Fred Bess search for seeds on October 2. All 19 are on the sunniest side of the tree (see the tall Blue Spruce at far right). All seeds are hidden/protected from winter winds by growing on interior branchlets of the kind of dense, Christmas-tree form that Torreya saplings assume when afforded a lot of sun. (Surroundings must be mowed to make this possible; otherwise, regrowth forest and shrubs shoot up much faster than torreya can grow.)
The seeds will become orange-purple when ripe in late October. Squirrels will likely be able to steal the seeds from the lowest branches, but the needles are so sharp (notice the gloved hands) and the tree so shrubby that the several that are 2 or 3 feet high may be safe from rodents.
Visit the Cleveland Ohio Torreya webpage, for the full image-rich, year-by-year report of Fred's set of four torreyas (2 females, 2 males), and WATCH VIDEO (below):
1. These trees have put forth leaves well acclimated to severe cold spells in Ohio.
2. Seeds are produced only on the branches that receive nearly full sun. (Connie notes from her 2005 site visit to wild California Torreya habitat that this seems to be a standard of the genus.)
VIDEO: 14 minutes, filmed 2 October 2018
February 2018: Learning Florida Torreya's capabilities by visiting its California cousin
In 2005, Connie Barlow visited 4 forested regions in California where Torreya californica could be found growing in the wild. Her aim was to experience and photo-record observations of the trees and their surrounds such that volunteer planters of the Torreya species native to the eastern USA (along with professionals in charge of this endangered species' recovery) could discern habitat preferences of the genus and thus pinpoint similar environments in eastern states for planting seeds and seedlings.
Photo-essays of California Torreyas from her 2005 site visits have long been posted on this website, but in 2018 she edited them into a VIDEOBLOG in two parts: Part 1 (25 minutes) and Part 2 (27 minutes).
Key photos include those that demonstrate the ability of Torreya californica (a subcanopy tree) to grow on exceptionally steep and shady slopes even in the company of forest giants such as Coast Redwoods and Douglas-fir.
LEFT: Connie extends measuring tape around one trunk of a double-trunked tree in Kings Canyon Sequoia National Park.
MIDDLE: This genus keeps resprouting new basal stems, even when disease-free, in quest of sunlight. The moss-laden left-leaning stem is still alive and has sprouted a series of vertical branches along its now-horizontal stem (Coast Range near Calistoga).
RIGHT: Another example of a downslope-leaning healthy stem sporting vertical stems reaching for dappled sunlight. (Coast Range near Calistoga).
December 2017: Torreya seedlings are HARDY IN NEW HAMPSHIRE
DAEIN BALLARD received seeds from 2013 harvest, germinated them in his greenhouse, then outplanted the seedlings in 2015. Two years later he reports:This year (2017) no more of the Torreyas from the first planting died. We had a wetter than usual year and I'm not sure if that was a shocker for them after last year's drought. However, only a few seeds that I planted out a couple years ago germinated, and all of the new seedlings were eaten by rodents. I have seedlings from Jeff that are from the same stock/year as those that I will plant out in the spring.
It seems to me Torreya can survive in a central New England climate like mine, though the competition from other better-adapted trees may be a bit stiff for them. Although the Torreya's endurance (for my climate) as seedlings seems mid-range from the other trees I've dealt with. They don't sprout nearly as aggressively as Chestnuts or Oaks. They do however seem to be more tolerant of environmental changes after they have sprouted (Chestnut and Oak seedlings died where Torreya survived in last year's drought). They are much heartier than the Pawpaws I planted (not one seed germinated and the seedlings need to be babied). The healthier Torreya I had that I planted in full sun lost most of their needles pretty quickly last spring due to the drought the previous year. They put on new growth but time will tell if they recover.
I've also attached pics [left] of the potted seedling Jeff gave me a few years ago. It's done great where I planted it. We got hit by a snow storm followed by an ice storm and it's still doing good. The female rooted cutting I got from Nearly Native Nursery is also doing well. The branch that broke last winter seems to have completely healed and recovered. It also pulled through the ice storm. It'll be interesting to see how these trees fare when they are larger and get hit by an ice storm. I have a feeling the seed-grown trees will do better due to their Christmas-Tree shape vs. the random bush-like shape of the rooted cuttings.
0CTOBER 2018 UPDATE (Daein Ballard, New Hampshire): "It seems that direct contact with ice on the Torreya needles damages them. Snow that falls on them doesn't seem to cause damage (in fact, snow seems to provide protection), but it's when it rains on them and then the rain freezes on the needle. I looked around and I was surprised no one has seemed to notice this before, since ice storms are more common in the south than in New England.
November 2017: Superb way to naturally DETER RODENTS
1. WHEN "FREE-PLANTING" SEEDS: Although there are no ways to absolutely ensure against losses when "free-planting" Torreya seeds directly into forest soil, we now have enough experimental evidence to suggest some best practices for this form of planting. But first, let's remember the definite advantages of free-planting: (1) avoids root trauma as well as water, soil, temperature, and sun "shock" that potted seedlings may experience when out-planted; (2) offers best opportunities for early and long-lasting establishment of mycorrhizal fungal associates; (3) eliminates possibility of taproot repression; (4) offers best opportunity for local climate adaptation during the seed's prolonged embryo development prior to germination.
LEFT: Diana Spiegel takes Connie Barlow on a tour of her free-planted Torreyas on 9 November 2017. In September she had noticed that 7 of the 12 seeds she planted spring 2016 (from fall 2014 seed harvest) were now 4 to 6 inch tall seedlings. All were planted on this south-facing forested slope along a creek south of Dayton OH, deciduous canopy.
Each seed had been planted 6 inches deep and was surrounded by a mesh of chickenwire also buried 6 inches (and staked). Confirming that Torreya seeds easily sprout at that depth is important news for future free-plantings seeking rodent protection via depth.
LEFT: Chris Anderson points to a newly sprouted Torreya seedling in his Cumberland Plateau stewardship forest.
By far the most expansive and exciting experiment in "rewilding" Torreya taxifolia into northward states began in November 2015 on 232 acres of the Cumberland Plateau of Tennessee. All 400 seeds were "free-planted" directly into the ground either 3 inches deep or under rocks to protect the seed from rodent predation. Two years later, Connie Barlow video-documented the beginning success of 38 new seedlings.
2. WHEN OUT-PLANTING POTTED SEEDLINGS: Over the years, we have learned the hard way that, when out-planting seedlings into their final patch of ground, it is crucial to shake out any perlite that might have been in the potting soil. If the soil around the stem and roots is more attractive than the surrounding soil for small rodents to burrow through, then the Torreya is doomed. (See examples of rodent damage in the December 2016 entry below.) Now we have learned that it is easy to make the planting soil even less attractive to rodents than the natural soil that surrounds the hole. Jack Johnston (GA) and Clint Bancroft (TN) report success with this technique: Simply, add gravel and/or pieces of shale to the soil mix you use to fill the hole!
March 2017: Learnings from Ex Situ Seed Propagation Sites in Oregon
In February 2017 Connie Barlow visited 2 ex situ Torreya taxifolia propagation sites in Medford, Oregon. The four specimens were planted 22+ years ago by Medford resident (and plant expert) Frank Callahan, who led Connie on a tour of these sites. He also donated to Connie a bucket of 1,000 seeds harvested from the 2 specimens that, together, produce prolifically. The prolific pair are seed-grown, while the pair rooted from cut branchlets produce mostly small, woody (infertile) seeds. All four specimens were originally sourced from the National Arboretum in Washington, D.C.
Watch the 24-minute VIDEO: "Florida Torreya Seed Production in Medford, Oregon (2017)"
LESSONS & NEW EXPERIMENTS:1. CAN WE OBTAIN VERTICAL TREE FORM GROWTH FROM CUTTINGS? Confirmation that rooted branchlets will not develop into single-stem trees (they adopt a shrubby form). This is advantageous for early pollen or seed production, but it is inconsistent with "rewilding" this species into regrowth forests poleward of its Florida range.
Frank Callahan will begin an EXPERIMENT in clipping the vertical "sports" on the tips of branches of the two shrubby specimens and attempting to root them in ways that might yield specimens that ultimately grow in the form of a single trunk that is indistinguishable from seed-originated trees (except possibly still lacking basal ancillary stems).
DECEMBER 2017 UPDATE: Torreya Guardian Clint Bancroft is experimenting with rooting leaders cut from the basal sprouts (leaders cut from mature trees in Madison FL, Columbus GA, and Highlands NC). Such leaders already display the vertical growth pattern, and thus our hypothesis is that rooting such will yield specimens with the same vertical aptitude as displayed by specimens grown from seed.
JULY 2018 UPDATE: Connie Barlow just noticed that an online list of actions included in the official recovery plan (USF&WS) confirms that rooting cuttings from vertical "leaders" (such as those found on basal sprouts) is necessary for nurturing a tree-like v. a shrub-like growth form: "The ABG has switched to propagating cuttings made from 'leaders' (the rapidly growing apex of a tree). This process forms upright plants of about two-feet tall in about two years." See the 17th column ("Comments") of the 11th row (action #322) at Recovery Plan ad hoc Report Results.
2. SHADE/SUN PREFERENCES & TOLERANCES. Florida Torreya is harmed by sudden exposure to direct sunlight. Ecologically Torreya taxifolia is a subcanopy tree species, and further observations of the total plantings by Torreya Guardians will help to answer which shade conditions are ultimately recommended as a balance for encouraging growth, yet keeping specimens safe from summer drought and icy winter winds. (Frank and Connie agreed that east-facing sun exposure is the safest.) Note: Watch 16:18 timecode of the Torreya Guardians VIDEO: "Florida Torreya Grove at Biltmore Gardens NC: 75 years old." There you will see that even ten years after a hurricane destroyed a pine overstory, thus exposing the Torreyas to sudden direct sunlight, the trees have not recovered. While there is no visible sun-scald, the only rich vegetative growth is lower down the trunks including tall, brushy basal growth on the full-sun side of two of the trees. As with lush basal growth in Coast Redwood trees following topping or loss of the main stem, it is possible that this flush of basal growth may be the fastest way for the tree to regenerate photosynthetic capacity and thereby keep alive nearly all of its mature extent of root development before it attends to producing a new leader that can resume upper-level growth. California Torreya is possibly more sun-tolerant than Florida Torreya is.
UPDATE ON SHADE V. SUN, APRIL 2017: Daein Ballard (see his New Hampshire Torreya project) is a molecular biologist, so a query to Torreya Guardians from a USDA soil scientist, Anita Koehn, was forwarded to Daein. "Diurnal patterns of chlorophyll fluorescence and CO fixation in orchard-grown Torreya taxifolia", by Anita C. Koehn and Robert I. Doudrick was published in 1999 in Journal of the Torrey Botanical Society. Torreya Guardians has long experience with (a) the importance of leaves supporting photosynthesis for multiple years, yet (b) the detrimental effects of moving potted seedlings with shade-adapted leaves into sunny environments when outplanting. Daein's hypothesis thus far:"... I made sure to collect samples of both the needles that grew in the shade and the needles that grew in the sun. Within minutes of collecting the samples, I imaged them alive under a light microscope at 200x with no stain. I imaged them both dry and wet (the needles submersed in water). I've attached some crude images I took with my cell phone through the eyepiece. I'm not an expert in this area but it seems the stomata on the sun-grown needles are smaller. Additional to that I noticed that it seems the stomata on the shade-grown needles stay open even when dry, while they are mostly closed on the sun-grown needles when dry. When wet, both needle types had open stomata..."
December 2016: Preventing Rodent Destruction of Torreya Roots
2018 UPDATE: Jack Johnston (GA) and Clint Bancroft (TN) suggest that, when outplanting potted seedlings, it is a good idea to add gravel and/or pieces of shale to the soil mix. This makes the soil around the torreya roots and stem even less attractive to burrowing rodents than the surrounding forest soil! In addition, it is crucial to still shake off the perlite! See below for what happens when the perlite is not removed nor gravel added.
Even 8 or more years after growing in open or forest soil, small Torreya trees are still vulnerable to ground-burrowing rodents that kill the trees underground by nipping off small roots and completely gnawing off bark (presumably for food value) of large roots in the upper soil layer. Wire cages protecting lower stems do not protect against below-ground gnawing. While there is no fail-safe way to guard against burrowing rodents, you can make the soil less attractive to rodents by (a) shaking off the perlite/potting soil mixture when out-planting a potted seedling and (b) having the surrounding "mulch" layer be no different than that found in the immediate surrounds.
In 2016 Connie Barlow video-recorded the sudden, over-winter deaths by rodent herbivory of three previously lush-growth Torreyas. You can watch the video segments at: 2 Torreyas killed at roots in Junaluska NC and 1 Torreya killed in Brevard NC. (The previous links will take you to the exact timecodes within the long videos where the dead trees are discovered.) Below are still images drawn from the videos.
PHOTOS ABOVE were taken from the Video of 1 Torreya killed in Brevard NC. See how the roots and the living bark have been entirely gnawed away. Notice the light-colored pellets in the root photo; these are perlite. Perlite and soft soils must be shaken out of roots prior to planting. Perlite + surrounding packed soils we now know will vastly increase the rodent herbivory prospects of even carefully tended outplantings.
PHOTO LEFT was taken in Spring 2016 by Connie Barlow at the Corneille Bryan Native Garden (Junaluska) site near Waynesville NC. That was where Torreya Guardians planted 10 potted seedlings in July 2008.
We found the plant (and its above-ground metal cage) laying on their side. The perlite-infused soil was easy digging and we immediately unearthed a chipmunk-size rodent tunnel and rodent-gnawed roots. One more of the 2008 planted Torreyas was also found in the same condition.
Previously at the Junaluska site, 3 Torreyas had been killed by rodents their first winter. All 5 deaths are in the plantings closest to a set of bird feeders at a seasonally occupied home. Equally important is that one can see tiny specks of perlite in the loose soil of the photo left.
In the 2016 Junaluska VIDEO, at timecode 05:55 you will hear Connie Barlow speculate on her Seasonal Birdfeeder Hypothesis for the rodent root damage. At timecode 26:25 she locates a nearby bird-feeder. On reflecting later, however, she regards the Perlite Hypothesis as a likely more harmful causative agent. See a 2016 report posted by our NH Torreya Guardian, Daein Ballard (posted 22 July 2016), on his observations of how best to deter chipmunks.
So we have learned the hard way: Shake off the perlite before planting out. Note that this problem of out-planting soils being more attractive than the natural soil can be alleviated by directly planting seeds into the outdoor soil ("free planting") exactly where you hope they will keep growing but free-planting has its own substantial rodent hazards that require specific actions to curtail.
2016: Apical recovery from herbivore nibbling
LESSON: Seedlings do recover from even severe apical herbivory, thus resuming a vertical growth form.
PHOTO LEFT: Mid-June 2016 the right-most seedling in the pot shows new-growth trending to become the new main stem, following previous herbivorous destruction of the main stem apical leader.
PHOTO RIGHT: October 30, 2016 shows the same seedling on the day it was planted out into wild forest. It is photographed from the same angle as photo left. See that the spring new growth has now matured into vertical apical growth. But notice that the nipped-off stem also produced new apical growth from directly beneath the nipped-off top. So now there are two apical stems.
2017 UPDATE ON APICAL RECOVERY:
Photos below by Nelson Stover (Torreya planter in Greensboro NC) in sequence Nov 2016, May 2017, and Nov 2017 shows herbivore devastation followed by recovery (both budding from stem and emergence of basal sprout).
2016: Surviving Extreme Cold and Drought in New Hampshire
Daein Ballard is a northern-most Torreya Guardian (s. New Hampshire) for whom 2016 offered supreme tests of Florida Torreya's ability to survive extreme winter cold and extreme summer drought. His reports:
COLD: February 2016: "Last weekend it got down to -14F, with a wind chill of -40F, which is a new low temp since I moved here. I've looked at all the Torreya and in spite of their young age they all pulled through completely unscathed. Since then it's gotten over 50F twice to give the seedlings a chance to show signs of damage if there was any. This is with all of the seedlings being at least partially exposed, since the snow was only a few inches deep. Even the most exposed seedlings in open areas show no ill effects."
DROUGHT: August 13, 2016: This summer has been the driest summer since I moved here. Although it has caused some yellowing on the more exposed seedling's needles, most seem to be doing fine. Other than when I first planted the seedlings, I haven't provided any supplemental water."
September 2016: "Just to give you an update on how things are going with my Torreya. Most are doing well, however this area is experiencing an extreme drought like nothing I've seen around here in my lifetime. All but two of the Torreya have made it this far unscathed. Two of them have died back, but put up new basal shoots. We'll see how all the rest make it through next winter; it's been really stressful for most plants around here."
2016: Importance of planting where MYCORRHIZAL FUNGI flourish
VIDEO 13b: Florida Torreya to Ohio's Dawes Arboretum (pt b) 2016
Documents superb annual growth on the two Florida Torreya specimens beneath a full deciduous canopy (and protected from winter winds by a border of evergreen conifers). Confirms 1-month difference in vegetational budburst bt the Florida Torreya (May budburst) and adjacent Chinese Torreya (June budburst). Speculation on the importance of nearby maple helping the Torreyas by shared fungal root symbionts.
17 minutes - filmed June 18, 2016
In 2016 a paper was published in Science that requires an immense worldview shift in how we study and interpret forestry results. "Belowground carbon trade among tall trees in a temperate forest", by Tamir Klein et al. (2 pages), is a must-read for all Torreya planters. Planting Torreya seeds or seedlings beneath a mature deciduous canopy will ensure drought and winter-wind protection, while offering opportunities for the young trees to receive sugars from the canopy via fungal root connections so long as canopy trees include those using ENDO (not ECTO) mycorrhizal types. Note: This recommendation is an addition to the "Encouraging Symbiotic Mycorrhizal Fungi" section on the Torreya Guardians Propagate webpage.
2016: New occurrences of FREE-PLANTING success
Shoal Sanctuary, Florida. May 2016 (by Chris Larson): "We searched Grotto Ravine yesterday and are happy to report five more sprouts. The count is now 11 of the 40, alive and well. Most are in wetlands but one is ten feet above a creek, fairly dry. I'm documenting every observed detail. June 2016 (by Chris Larson): We're a bit concerned. All 40 of the Shoal Sanctuary seeds were planted at only 1 inch deep. One was dug up within a month. This year we found 11 seedlings in May. Went back to check in June: 2 seedlings have vanished, but 2 others elsewhere have now sprouted. So we are still at 11 of 40 and counting.
Greensboro, NC. NOV 2016: Nelson and Elaine Stover revisited all the planting sites. None of the 20 seeds planted from the autumn 2015 seed stock are yet visible above ground. But 10 of the 30 seeds of the 2013 harvest had visible sprouts (a germination rate of 1 in 3).
Southeastern Ohio:After two winters in the ground, 3 of the initial 18 seeds "free-planted" were visible above ground in June 2016. All 18 seeds had been intentionally planted on very steep slopes in full-canopy deciduous moist forest in a ravine. The intent was to ensure that no buck deer would be able to rub against a torreya sapling to dislodge antler velvet. All 18 seeds were planted shallow in the soil, with no rock protection and all 3 successes are very near downed logs or large branches.
Conclusion: As of 2016 Connie surmises that free-planting Torreya taxifolia seeds directly into forests with no rock protection will yield severe losses owing to seed-herbivory.
TWO POSSIBLE EXCEPTIONS that need further testing:1. Perhaps burrowing, seed-predating voles and chipmunks may be rare on very steep, moist slopes indicative of year-round near-surface water seepage. Such slopes may simply be too moist (or subject to tunnel-collapsing solifluction) for the little rodents to establish below-ground tunnels.
2. Perhaps planting seeds 4-inches deep into forest soils will help the seeds evade rodent detection. (One experiment is underway.)
MARCH 2016: Posting of 2015 v. 2006 measurements, BILTMORE GARDENS, NC
In 1939 Chauncey Beadle supplied the Biltmore Estate with a dozen Torreya taxifolia seeds or specimens collected in Florida prior to any understanding of climate change and endangered species. Now this 75-year-old grove and its offspring are precious for securing the wellbeing of the species and for demonstrating that (with little human help) North Carolina is an ideal habitat for escaping the native diseases of a now too-warm Florida.
LEARNINGS: Torreya grows slowly; evidences none of the diseases afflicting the species in Florida; uses basal sprouting and ground-extending low branches to maximize access to sunlight when beneath a closed canopy. April 26 video shows 3 males in different stages of pollen ripening possibly caused by differential access to direct sunlight.
Full information at Torreya Guardians Biltmore webpage. Also, click VIDEO below.
posted and narrated by Connie Barlow
JANUARY 2016 VIDEO OF TORREYA NATIVE RANGE IN FLORIDA
VIDEO: Site Visits to Florida's Endangered Torreya and Yew Trees
Connie Barlow presents 15 years of baseline photos and videos she recorded of Torreya taxifolia and Taxus floridana in their historically native range in Torreya State Park in northern Florida. This video offers visual baseline data, including the context and plant associates that remain in this once peak glacial refuge (where the ailing Torreya species was "left behind" and now decimated by a too-warm climate).
2015 VIDEOS OF REWILDING RESULTS & LEARNINGS (North Carolina)
FL Torreya to North Carolina: 2015 progress report (Waynesville, NC)
First video-documentation of fate of historic 2008 rewilding action of the endangered Torreya taxifolia from Florida to North Carolina. Connie Barlow films and narrates a survey of the 21 plants in wild forest on the slope of Eaglenest Mountain, near Waynesville. Most important results are both positive and negative, which help us ascertain the habitat preferences of this species (moisture, shade, slope, aspect).
FL Torreya to North Carolina (pt 2): 2015 progress report (Junaluska, NC).
Second half of video progress report on our 2008 rewilding to North Carolina. Key findings include recommendations for measuring vigor, perils of cohabiting with rhodies, long-term negative consequences of planting root-bound conifers, the stress of seedlings needing to re-orient growth to wild light conditions. Note: The final 12 minutes of the video include the Waynesville findings in the comparative assessment.
Free-Planting Torreya Seeds into Wild Forest: 2015 report. Best practices discovered by Torreya Guardians in attempting to plant seeds directly into the soil of wild forest in the southern Appalachian Mountains. Preliminary results confirm that planting beneath flat rocks and beneath a thatch of branches were both effective in deterring squirrels. However, the results are mixed for voles. This video chronicles Connie's visit to the Waynesville NC site 17 months after planting seeds.
FL Torreya to Franklin, North Carolina: 2015 progress report
Russ Regnery leads Connie Barlow on a tour of his young torreya trees. Topics include (1) the advantage of using a shading screen during early years if Torreya is in full-sun, (2) Torreya is vulnerable to winter sun and wind desiccation if not protected by a canopy, (3) advantages of planting near nurse trees for shading and sharing their symbiotic root fungi. "Free-planting" seeds from the 2014 seed harvest directly beneath the forest canopy is final half of video.
15b: Germinating Torreya Seeds: 2015 report
Jim Thomson, Lee Barnes, and Connie Barlow discuss what we all have learned thus far about how to germinate Florida Torreya seeds outdoors, in locales far north of the "historically native range" of this endangered conifer species. Seeds harvested from the same mother tree in the same year will span a number of years to germinate, even when planted under the same conditions.
• DECEMBER 2015: First success of "FREE-PLANTING" SEEDS UNDER ROCKS
Connie Barlow reports 5 seedlings newly emerged from beneath large flat rocks 2 years after planting. The free-planting section of the Propagate page contains the detailed photo-essay.
Results include: (a) Never plant seeds under or near a log; (b) Rocks distant from vole hiding places work best; (c) Expect the seedling to emerge always on the upslope side of the rock; (d) Success rates for good placement of rocks probably range from 20 to 50% max; (e) Expect seedlings to become visible above ground in about 2 years minimum (after 2 winters).
Barlow recommends these additional questions for volunteer testing: (1) Are there any insects (ants?) detrimental to seed germination under a rock? and (2) If a seed is planted very deep (approx 4 inches) out in the open, with no rock protection, will squirrels be unable to smell it?
2018 UPDATE: It is dangerous to cover seeds with a big rock on flat ground because (1) the underside will stay dry, owing to no down-slope seepage, so ants and even rodents may occupy the area, and (b) if there is no obvious side for the germinating radicle to grow "up" it may grow in ever-widening circles, eventually running out of energy stored in the big seed.
SPRING 2015 DATA CHARTS OF WAYNESVILLE and JUNALUSKA 2008 PLANTINGSData Caveats: (1) April 1 was too early for the vegetative buds to expand, so some assessments of terminal buds at the Waynesville site (presence or absence) may prove faulty. (2) A few weeks later at the Junaluska site, I noticed for the first time vegetative buds appearing through the bark of older branch segments and even the main stem itself, so bud counts at branchlet ends may under-report tree vigor. (3) Because the potted seedlings we planted in 2008 were all "root bound" (too long in the pot), some had to abort their main stem a few years after planting and put all their energy into growing the basal sprouts.
Waynesville, 1 April 2015
Junaluska, 25 April 2015
• 2015 LEARNINGS ON PROPAGATION & REWILDING BEST PRACTICES (posted by Connie Barlow)1. Beware of planting ROOT-BOUND potted seedlings. As shown in the Junaluska video above, the Torreya taxifolia seedlings we purchased at a nursery and planted in 2008 were "at least 2 or 3 years too long in the pot." That made them "root-bound", which is especially problematic for a tap-rooted tree (which Torreya is purported to be). Hence our "rewilding" experiment began with an inherent impediment. By 2015 (or before) several of the trees had allowed their original main stems to die, and were putting all effort into converting one or two basal sprouts into main stems with a fully vertical central component and apex bud. Nonetheless, all 7 plants at the Junaluska site are thriving, and all specimens at the Waynesville site planted on the moist, east-facing slope (with creek and waterfall nearby) are healthy. Only 5 of the 21 potted seedlings planted at the Waynesville site in 2008 were on that favorable slope; thus 17 of the originals are either dead or struggling.
2. Selecting among three planting options: (a) potted seedlings, or (2) "free-planting" seeds or (3) sprouted seeds directly into wild forest soils. Because Torreya has a large seed and because it has delayed germination, planting potted seedlings is the best way to avoid seed predation by rodents. Nonetheless, tending pots of seeds and then carefully planting the seedlings is time-consuming and requires some expertise and periodic watering. Also, we have noticed that branch patterns and leaf propensities fine-tune for the sun-shade conditions they grow in; so planting into different conditions will stress the plants to reorient their growth patterns. What about "free-planting" seeds directly into forest soils? Experiments are now underway (2013 in NC, 2014 in MI, and 2015 in NC and OH) using different degrees of avoidance of or protection against rodents. See the free-planting section of our Propagate page. Several videos also portray our "free-planting" experiments in action:Ludington Michigan 2014, Wolf Creek NC 2015, Franklin NC 2015, and Waynesville NC 2013 (report of 2015). (The only seed-planting video that reports on preliminary results is the Waynesville video.)As to free-planting sprouted seeds, this is a new idea in 2015 by Torreya Guardian Fred Bess of Cleveland OH. Fred reports that of 150 seeds harvested autumn 2014 and stratified over the winter in damp peat moss, 27 germinated by May. This is an 18% rate of first-year germination. Connie reports a much smaller germination rate, when 2014 seeds overwintered in peat-moss in a protected container, outdoors in n. Alabama (temperatures as low at 15F); but Janet Manning reported a high proportion of over-winter germination a previous year in her garage. The key advantage of free-planting sprouted seeds is that, while still somewhat vulnerable to rodents, first-winter predation has been eliminated.
3. Deciduous canopy protects young trees during summer heat and drought, while offering full-sun habitats in late fall and early spring. Consistently, Torreya Guardians report that full-sun sites require partial shade screens at least in the early years. The exception, of course, is if the trees are on an automatic irrigating system. See the Shoal Sanctuary Video for an example of full-sun, full-irrigation thrival.
4. Preference moist, east-facing slopes. Our 2008 rewilding experiment at a mountainous property near Waynesville NC confirms that, at least at that latitude and elevation, east-facing slopes (in which moisture-loving wild plants already are found) are the best habitats. The slopes and flood-free areas of ravines may also be good choices.
5. Locate trees where they are protected from winter winds. While many of our trees are planted beneath wild forest canopy (and some in ravines), others have been planted in areas exposed to winter winds. Northerly exposures are especially disastrous in northward states. The most graphic examples of what happens to Florida Torreya when exposed to temperatures sub-zero F are in Ohio. The Dawes Arboretum 2015 video (near Columbus OH) begins with a beautiful torreya growing amidst dense shrubbery and beneath a giant white oak. That tree shows no damage from the brutal "polar vortex" the preceding winter. In contrast, near the end of the video you will see a torreya located on a north-facing slope with a half-mile of unimpeded landscape northward; all but the terminal stem and bud suffered complete leaf-kill. In addition, our Cleveland OH torreya webpage posts photographs of terrible winter-wind kill of the evergreen leaves in the winter of 2013/14 (although the subsequent video shows full recovery 6 months later); that location is also unprotected by shrubbery or woodland surrounds.
6. Might southern Ohio be superb habitat? Southern Ohio is broadly in the same "plant zone" as the mountains of North Carolina Zone 6. (Recently the USDA has revised the maps owing to climate change; Zone 6 now extends even into southern Michigan.) Thus, while experimental plantings in Cleveland OH and the lower peninsula of Michigan are primarily to test for Torreya's extreme northern range limits in today's climate, it is possible that southern Ohio might join western North Carolina as ideal climate regimes right now that is, so long as plantings are protected from summer drought by deciduous canopy or ravine placement and from brutal winter winds.
7. Supplemental hypothesis on why Florida Torreya was "left behind" in its peak glacial refuge of Florida's Apalachicola River: While Barlow's 2015 new hypothesis has nothing to do with ascertaining northern range limits and discerning preferred habitats in the southern Appalachian Mountains, it does open a new consideration for understanding the "deep-time" migratory habits of this conifer. The new hypothesis is this: Might Torreya taxifolia have become stranded in its peak glacial refuge, not so much because of the slow seed-dispersal capacities of squirrels (as hypothesized by Barlow here and here) but because of the absence of northward flowing rivers between Florida and the southern Appalachians? Barlow arrived at this hypothesis during a field visit to the largest remaining Torreya taxifolia in existence: the one along the Chattahoochee River, in the front yard of a historic-register home at the riverfront. (Click on video below.)
While visiting the sole remaining T. taxifolia in Columbus GA, Connie Barlow was struck by its location along a free-flowing section of the Chattahoochee River. The Chattahoochee is the main conduit between the peak-glacial plant refuge in n. Florida and the Appalachian Mountains. Might Torreya taxifolia have been "left-behind" in its Florida refuge because the Chattahoochee River flows southward? The tree could have dropped seeds into the river for a speedy journey south, but it would have been utterly dependent on the slower actions of squirrels for the the return trip north.
Note: In a 2010 email, Lee Barnes made a similar speculation, "I am curious if the floating seeds might have aided distribution of a species now primarily found growing along a major river?"
2014 and PREVIOUS LEARNINGS
• MAY 2014 - LEARNINGS TO PURSUE:
Connie Barlow writes: "We need to learn more about how to encourage mycorrhizal fungi to attach to the roots of any seeds or seedlings we plant in the future. Jeff Morris reported seeing mycorrhizal fungi on the roots of Torreya seedlings that I collected beneath a mature T. taxifolia tree in Clinton NC last fall, and ever since I have been reading about the importance of encouraging such fungi to work with our plantings. (Read about mycorrhizal symbionts and Jeff's ideas on our propagation page.) Someone should visit the Clinton NC tree, dig up more seedlings, and study the mycelium on their roots (the seedlings easily gain fungal symbionts because they sprout directly beneath the mother tree). Also, someone should carefully examine a bit of root from samples of our plantings in Waynesville and Junaluska NC.
Hypothesis to test: Do the two tallest seedlings from our 2008 plantings in NC (both at Corneille Bryan Native Garden) have the best developed symbiotic fungi on their roots? Both are very near a white pine so we need to test whether planting Torreya near a living conifer (and of what species?) is the best way to ensure that seeds and seedlings attract the ideal fungal partners.
March 2015 UPDATE / by Connie Barlow, Torreya Guardian / Now we know that Glomus is the fungal symbiont for Torreya and which trees naturally harbor that genus of mycorrhizae
In early March I had email communications with a Smithsonian molecular plant ecologist who did research on Torreya taxifolia, but who has not yet published her results in a scholarly paper. We are grateful that Melissa McCormick gave us a summary of her findings. She identified Glomus as the genus of mycorrhizal fungi that associates with Torreya taxifolia. I have added her advice and the list of common trees that do harbor Glomus and the list of those that do not. Visit this section of the Propagate page: Encouraging SYMBIOTIC MYCORRHIZAL FUNGI. Henceforth, we would be wise to mix into pots for seed germination soil from beneath favorable tree species in the locales where ultimately the seedlings will be out-planted.
• 2014 - WHAT OTHERS ARE LEARNING FROM TORREYA GUARDIANS:
"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, which broadly denotes the actions undertaken by Torreya Guardians.)
• NOVEMBER 2013 REPORT
Connie Barlow gathered seeds from the Clinton and Mt. Olive (North Carolina) Torreya trees on 31 October 2013. She then recruited 2 new landowners in North Carolina Cullowhee and Greensboro to plant Torreyas on their wild, forested properties.
Along the way, she did a genetic exchange with Torreya Guardian Jeff Morris (Spencer NC) to increase the diversity within existing and future plantings.
Connie then created a 75-minute VIDEO (right), posted on Youtube, to summarize our learnings to date.
As well, a welcome surprise came during Connie's October site visit to the Evans property in Waynesville. There, she witnessed superb new basal growth from 3 of the trees that had been struggling on the dry, east side of the property: Johnny Appleseed, Charles Darwin, and Joanna Macy specimens. The new growth surely results from the very rainy summer in the Waynesville area.
A.J. Bullard proves a single tree can produce both male and female cones.
APRIL 2013 STATUS REPORT
Leaf bud counts and vertical stem measurements at Evans property were by Lee Barnes; data recorded in field notes by Connie Barlow. Bud counts and stem measurements at Bryan Garden by Connie Barlow; data recorded in field notes by Michael Dowd.
The big news in assessing the health of our 2008 seedlings planted at the Evans property near Waynesville NC and the Corneille Bryan Native Garden in Junaluska is three-fold:
(1) Corneille Bryan plants are thriving
(2) Mixed results at Evans property
(3) New quantitative data format
The table at left shows the results of end-April data collection. Only the healthiest plants (those that are thriving or at least have a chance to better establish and grow) are shown at left in order of health.
BRYAN GARDEN: Of the 31 potted seedlings planted July 2008, 15 remain in excellent or reasonable health. Except for the 3 seedlings killed by gnawing voles at Corneille Bryan Garden during the first winter, all 7 remaining there are thriving. (These are marked by a prefix of "1" before the plant's name in chart at left.)
EVANS PROPERTY: The 3 plants nearest the waterfall (to the west of the creek) are doing well. These have the prefix 2W and are named Maxilla, Celia, and T Berry. The 2 plants farther from the falls on the West side are in fair condition: Bob Z and Annie. Only 1 of 4 seedlings that were planted centrally (2C) is in fair condition. And on the dry east side of the property (2E), only 2 of the initial 12 seedlings planted there are in fair condition. The other 10 on the east side are either already dead or in a consistently diminishing condition.
These results offer meaningful opportunities to begin assessing habitat preferences of Torreya taxifolia within the mountainous conditions of North Carolina. We welcome interpretive suggestions from knowledgable parties. Please continue reading this assessment and then click on the photo + data pages of individual plants (at the bottom of this page). Also, visit our North Carolina main page, as there are a half dozen other sites (some much older than ours) where Torreya taxifolia has been planted in garden or semi-wild settings in North Carolina.
MAY 2012 STATUS REPORT
Nearly four years have passed since our July 2008 "rewilding" of Torreya taxifolia (31 nursery-grown, potted seedlings) into the southern Appalachians.
This conifer tree was first visited and described by botanists in the 19th century. Historically, it has been recorded in the wild only in the rich ravine soils bordering a 65-mile stretch of the Appalachicola River in the Florida panhandle and adjacent southern Georgia.
Nonetheless, from a "deep-time" (Pleistocene and earlier) perspective, it is reasonable to hypothesize that for millions of years Torreya taxifolia lived mostly in the southern Appalachians and that it migrated into a well documented "glacial refugium" when Ice-Age conditions forced it (and other temperate species) far to the south. See the online pdf: "Paleoecology and the Assisted Migration Debate: Why a Deep-Time Perspective is Vital".
Following a May 2012 onsite assessment by Connie Barlow and Lee Barnes of both the Waynesville NC (Evans property) and Junaluska (Corneille Bryan Native Garden) plantings, we have begun to discern distinctions in habitat and success rates that will lead toward better management decisions in assisting this greatly endangered species within the yew family (Taxaceae) to make its way northward (and upward in elevation) as the climate continues to warm.
Following is an illustrated essay of what we have learned and what questions remain for adequately understanding the habitat preferences of eastern North America's species of genus Torreya.
CHARACTERISTICS OF HEALTHY NEW GROWTH
ABOVE LEFT: In studying all 31 specimens, we have learned that the most robust growth in the upper tier of radiating branches includes new annual growth that is both apical (vertically upward from the center of the main stem) and lateral (radiating outward horizontally). In the photo above left of the specimen named Wendell/Thomas Berry, you can see light-green new growth both apically and laterally. Notice ithat the new lateral growth is in the form of triplet branchlets, extending outward from the single-branched lateral growth of the apex the previous year.
ABOVE RIGHT: The specimen Julia Butterfly Hill shows a less healthy singlet growth form and no new apical growth. Both photos were taken May 2012, when it is still easy to discern the color (as well as texture) distinction of the new growth, which is a lighter shade of green.
DAMAGE BY VOLES
During the first winter (2008/2009) 3 of the 10 seedlings planted at the Junaluska site were killed by herbivory; Lee Barnes ascertained that voles had nibbled off the bark and cambium of the lower stem and root. The remaining 7 specimens were given wire cages, which remain. None of the 21 seedlings planted at the Waynesville site received cages, and none have been damaged by voles.
Vole-damage hypothesis: The Corneile Bryan Native Plant Garden at Junaluska is an isolated forest pocket surrounded by homes, whose intermittent stocking of bird feeders might artificially ramp up vole populations, which then crash when the feeding stops (and some residents depart for the winter). A possibly significant piece of evidence is that the 3 specimens that died were all located nearest to the lower end of the forest patch, not far from a home. More details are provided on the individual webpages for Chauncey Beadle, Hardy Croom, and Asa Gray specimens.
IN NC MOUNTAINS
Left is a photo of a deer-damaged Torreya in its "historically native" habitat (Appalachicola State Park, FL). Deer damage of sapling Torreyas is so severe in the park that USF&WS-sanctioned restoration efforts in the Florida preserves regularly install cages to preclude deer.
The migrated Torreyas in Junaluska and Waynesville NC are still too small to attract the attention of buck deer scraping off antler velvet. Even so, the owners of the Waynesville property on which 21 seedlings were planted in 2008 tell us they have witnessed no evidence of deer on their property. It is possible that the Junaluska site has some deer, owing to its expanses of mowed lawn, and thus abundant forest-edge habitat.
MIGHT DECIDUOUS CANOPY BE PREFERRED BY TORREYA?
ABOVE: Compare the two seasonally distinct photos above, taken at the Evans property site in Waynesville NC. At left, Russell Regnery stands by the just-planted specimen we named Thomas (or Wendell) Berry; photo taken July 31, 2008. At right, Chuck Dayton stands in exactly the same spot (compare the tree trunk at left in both photos) November 13, 2008. Although there are some clusters of rhododendron and mountain laurel on this property, it is otherwise deciduous at all levels: canopy, subcanopy, and ground. The (evergreen) hemlock trees that had been present on this property are all dead, and there are no pines and thus no evergreen trees in the canopy. Note: Connie Barlow's recollection of the Appalachicola site is that the Torreya specimens there are in some locations shaded by pine and/or the evergreen American Holly.
An important question is whether the evergreen Torreya accomplishes much of its photosynthesis in early spring and late fall when the upper and lower canopies are bare of leaves. Perhaps shade is important in times of summer heat and drought. (This is a question worth considering.)
CALIFORNIA TORREYA FOR COMPARISON
4 PHOTOS ABOVE AND BELOW: All of these photos were taken by Connie Barlow in 2005, during site visits to native habitat of the California species of Torreya (Torreya californica). The purpose of showing these California photos here is to suggest that it is ill-advised to attempt to ascertain the habitat preferences of the EASTERN North American species of this ancient genus without also becoming familiar with the range of habitats which currently support North Amercia's WESTERN species of genus Torreya.
ABOVE LEFT: A typical yewlike (planar) form of leaf growth on branches manifests when Torreya grows beneath a largely evergreen canopy of California Live Oak and California Bay Laurel. This photo was taken May 5, 2005 (by Connie Barlow) in Sequoia National Park, on a western slope at 4,100 foot elevation. More photos here.
ABOVE RIGHT: Once a Torreya breaks through into the canopy, it may take an astonishingly more luxurient growth form, as does this specimen just downhill of a road on a steep south-facing slope in Yosemite National Park, elevation 5,000 feet (photo taken May 19, 2005). Connie initially mistook this specimen for a Douglas Fir! More photos here. Note: The huge single seed encased within the fleshy sarcotesta of a Torreya provides a huge initial energy increment, which allows this species to grow even within a tumble of tall boulders that challenge it with shade during its first several years of growth. The multi-trunked specimen in this photo arises from such a bed, which you can see in photo 9 on the Sierras page.
LOWER PHOTOS: In the coast range of California, Torreyas typically are found in association with redwoods. When challenged by shade, they assume a yewlike growth form, as in the photo left below (with giant redwood right behind it; flash on camera automatically triggered because of the intense shade). The photo to the lower right shows, nonetheless, what a Torreya is capable of achieving even in a redwood forest. Connie is shown standing alongside the champion Torreya californica tree, which occurs on an elevated terrace of a creekbed that is only several hundred feet above sea-level, just five miles inland of the ocean north of Santa Cruz. The frequent fogs during the winter dry season likely have played an important role in producing a large number of very large (and canopy-tall) Torreyas within and on the slopes of this particular valley. See more photos here.
THE IMPORTANCE OF SITE VISITS
PHOTOS ABOVE: Connie Barlow strongly recommends that all persons in official decision-making roles with respect to ESA management of the endangered EASTERN species of genus Torreya make site visits to at least the Santa Cruz, Napa, Sequoia Park, and Yosemite Park native expressions of the western species. At minimum, the photo-essays of California habitats posted online by Connie should be studied and discussed.
As well, this photo-essay with links to more detailed photo pages is intended to acquaint all those with an interest in the future thrival of the eastern species of genus Torreya with the ongoing learning experiences that accrue via the volunteer work of Torreya Guardians in actual field tests of assisted migration into Appalachian habitats of various types.
GROWTH DIFFERENCES BETWEEN WAYNESVILLE AND JUNALUSKA
Above photos compare the most vigorous individuals between the two different properties into which potted seedlings were planted in July 2008. Left is at Waynesville of the "Thomas/Wendell Berry" tree. Right is at Junaluska of the "Henry David Thoreau" specimen. Both photos were taken in late May 2012.
The photos below show how similar in size the two specimens were when initially planted in July 2008, with Berry on left and Thoreau on right. The fact that the Berry specimen is not a great deal taller in 2012 than it was at planting is not a disappointment, as examination of the seedlings during planting revealed that they had stayed in their pots for a year or two or three too long and thus we expected some initial dieback and the likelihood of a long period of root establishment before a main stem would evidence obvious and sustainable growth.
SUCCESS RATE DIFFERENCES BETWEEN WAYNESVILLE AND JUNALUSKA
Connie Barlow created the matrix below (includes both Waynesville and Junaluska NC plantings) to help assess why some individuals are thriving, some are failing, and several died. Note that all the Junaluska trees show more luxurient growth than any of the Waynesville trees, on a "rate" system spanning 0 (dead) to 16. Although Junaluska initially lost 3 of its 10 initial plantings to voles, once short wire cages were added to prevent future losses, not a single specimen has died. More, every specimen in Junaluska is thriving.
In contrast, the matrix below shows a wildly varying success rate at the Waynesville site, with declines and deaths having nothing to do with voles. This high variability in success is welcome, as it offers the opportunity to begin discerning distinctions between favorable and unfavorable habitats and plant associations for this Torreya species.
ELIMINATING POSSIBLE CAUSES OF SUCCESS DIFFERENCES
Not SOIL SUPPLEMENTS: The column titled "S?" in the matrix above denotes whether or not soil amendments were mixed into the specimen at the time it was planted in July 2008. While all the Junaluska specimens were given soil supplements (marked by "Y"), less than a third of the Waynesville plantings received such supplements. Note that the two most successful trees at Waynesville (those rated a "10") received no supplements, and one of the two trees that died had received supplements. Overall, by analyzing the success rates within the Waynesville site, we see we can eliminate soil supplements as a causal factor.
Not SUPPLEMENTAL WATERING: For several months directly following the July 2008 planting, all specimens at both Junaluska and Waynesville were given supplemental water by hand. But after that, no supplemental watering was given. Indeed, with the exception of the basal stem cages at Junaluska and a bit of greenbriar pruning and hardwood-seedling pulling when photographs were taken, all individuals were left entirely alone thus with the freedom to live or die as "rewilded" individuals (that is, seedlings that had germinated in a nursery and which spent the first 4 or 5 years of their life in pots at a nursery).
Not GENETICS: Thirty of the 31 seedlings planted in total at the Waynesville and Junaluska NC properties in July 2008 are very genetically similar. Those 30 were purchased from Woodlanders Nursery in Aiken, South Carolina. The nursery owners wrote, "I believe all of the Torreya we have propagated and distributed in recent years (including the ones you refer to) were seedlings from plants here in Aiken. Years ago on a nearby estate we planted two female trees and a male. The females were cutting-grown from the famous old Torreya in Norlina, NC and the male was cutting grown from a specimen at the Henry Foundation in Gladwynne, PA.
Seedling No. 31, "Celia Hunter," was donated by Atlanta Botanical Garden. It grew from one of many seeds produced by the Garden's "potted orchard," which was cloned from branchlets harvested in 1991 from living original, wild trees in the Apalachicola pocket reserve. So this particular seedling has a pedigree directly related to the wild genotypes. (At the time of donation, the ABG had no idea that the donated seedling might be used in an assisted migration project.)
NOTE: Torreya Guardians are aware that the genetics of these plantings are dangerously inbred. We look forward to the time when the officials in charge of the Endangered Species Management Plan for Torreya taxifolia will conclude (with us) that the benefits (in both knowledge acquisition and species longevity) of assisting the northward migration of this highly endangered conifer far outweigh the possible risks of invasion and disease that some parties put forth as reasons to preclude experimentation with assisted migration as part of ESA plant management. At such time, the property owners at both sites would likely be very receptive to (a) additional plantings to increase the genetic diversity, and (b) ESA-sanctioned visits to monitor site progress. For more on this topic, see the online essay by Torreya Guardian Connie Barlow, "Paleoecology and the Assisted Migration Debate: Why a Deep-Time Perspective Is Vital." For access to the ESA management plan and other pro-assisted-migration comments that were filed, click here.
Lee Barnes returns to Evans Property site November 2008. Here, by seedling "Loren Eiseley," he displays a photo he took 20 years earlier of the biggest Torreya taxifolia tree: a female in Norlina, NC. She is "Grandma" to all but one (all but "Celia") of the 31 seedlings that were planted in NC July 2008. Note: Lee Barnes studied Florida Torreya for his PhD dissertation at the University of Florida (1985), available online: "Clonal Propagation of Endangered Plants: Rhododendron chapmanii, Taxus floridana, and Torreya taxifolia".
POSSIBLE CAUSES OF SUCCESS DIFFERENCES (for further testing)
Elevation Difference: The Junaluska site is 800 feet lower in elevation than the Waynesville site (2,600 feet compared to 3,400 feet). Lee Barnes, who lives in Waynesville, observes that during the winter there will often be moist snow falling up at the Waynesville Torreya site when there is only rain down in Junaluska. So this difference could be significant and calls for further investigation.
PHOTO LEFT: The specimen "Celia Hunter" after a moist snow at the Waynesville site in December 2008.
Amount and Timing of Direct Sunlight: In the matrix above, note the "Aspect" column. At a macro scale, all specimens at the Junaluska and Waynesville sites were planted on south-facing mountain slopes. But there were big differences in the micro-scale aspect, which is what is depicted in the matrix. Much more investigation needs to be conducted on the matter of sunlight (but, as noted below, "indicator species" may be a more practical site characteristic to assess).
It is important to know that by far the most successful individuals were the only two planted in pretty much full sun: "Hazel Delcourt" and "Henry David Thoreau." The photo below left shows the context of "Hazel Delcourt" immediately after planting in July 2008 (photographer is facing north, and Hazel is directly under the crouched man's left hand). At right is "Hazel Delcourt" in May 2012, which now just overtops the poster grid Lee Barnes is using to measure growth (photographer is also facing north). Note how lush all the new growth is in this untended part of the garden.
Hydrology: It is reasonable to surmise that, with the exception of perhaps the first year of site acclimation, specimens that grow in the most sunlight generally do best. Indeed, one of Connie's observations of naturally occurring California Torreya is that seeds are only produced on trees/branches that receive a good deal of direct sunlight. (See, for example, the captioned photos at the bottom of this page documenting a California site visit on the slopes west of Napa Valley.) However, too much sunlight can be problematic in seasonal drought times. Hence, the importance of hydrology. But, here again, a survey of naturally growing herbs and shrubs (and to a lesser extent, canopy trees) that are neighbors to a Torreya individual may provide the most direct and easy to acquire information about soil moisture levels. Hence, the importance of undertaking inventories of plant associations, as detailed below and, from those, working to determine "indicator species."
Soil Chemistry: Torreya Guardian Russ Regnery (and steward of out-planted seedlings near Franklin NC) supplements this field report with a suggestion that soil pH would be important to test as a possible causal factor in the growth differences apparent between and within the Waynesville and Junaluska sites. Direct testing along these lines would be useful. Nonetheless, as with the other possible causes, differences in associated plant species may also indicate soil chemistry differences.
Importance of "Indicator Plant Species": The MATRIX above includes a first attempt to catalog and compare possible indicator plant species.
BLUE font indicates moisture-loving plants
RED font indicates plants that are typically found in drier conditions
It is reasonable to conclude that hydrangia and trillium are indicators of plentiful soil moisture, and thus are likely good locales for planting Torreya. It is also reasonable to conclude that it is unwise to plant a Torreya seedling near sassafras, vaccinium, and flame azalea.
A classic OAK-HICKORY CANOPY is thus to be avoided which is precisely where we planted the cluster of 12 specimens shown on the matrix headed by the specimen named "Johnny Appleseed." The question, then, is Why (among those 12) are Johnny Appleseed and Charles Darwin doing so well? Careful site inspection, followed by group dialogue, would surely reveal important considerations.
WHAT ABOUT JEWELWEED IN JUNALUSKA? Impatiens capensis, jewelweed, is the only moisture-indicating species that was found (often in abundance) around all but one individual at the Junaluska site but at none of the Waynesville locales. A quick internet search reveals this:Impatiens capensis is an annual plant native to North America. It is common in bottomland soils, ditches, and along creeks. The preference is light shade to partial sun, wet to moist conditions, and a fertile soil with an abundance of organic material. Submergence of the roots by flood water is tolerated for up to 2 weeks without apparent ill-effects.Overall, now that the 2008 specimens have established (or died or severely declined), we have a terrific opportunity to make qualitative and quantitative observations that might lead to real breakthroughs in understanding the habitat preferences of America's eastern species of genus Torreya.
Experienced ecologists are encouraged to survey the matrix above and to click on the photo-essays for each individual specimen planted in Junaluska and Waynesville (the links to each specimen are listed at bottom). Please email your conclusions and speculations (and any advice for future on-site observations) to Connie Barlow: conniebarlow52 at gmail.com
"REWILDING" AS THE ULTIMATE GOAL
Ideally, habitats will be found not only where Torreya taxifolia may survive with continuing human-assistance, but also habitats where the species can sustain and propagate independently as it seems to have done in recent years, thanks to squirrels dispersing seeds at three verified locations: Biltmore Gardens near Asheville NC and on other private lands in Clinton, NC and Highlands, NC.
Ideally, humans will be able to help this conifer genus return to the rich deciduous montane forests of eastern North America as a self-perpetuating contributor to natural plant ecologies within the "discordant harmonies" and "ever-shifting" dynamics wrought by climate change and phylogenetic flows over the course of geological time. As some have speculated, perhaps Torreya taxifolia, over the course of millennia, might be able to fill in for the ecological devastation wrought by the invasive disease (woolly adelgid) that has virtually eliminated the only other canopy evergreen in moist low-mountain forests of the southern Appalachians: hemlock, genus Tsuga.
PHOTO LEFT: A naturally dispersed seedling on private lands in Highlands, NC. The photo was taken with a flash camera during a site visit in August 2006, made by Lee Barnes, Connie Barlow, Jeff Zahner, and two others. (Jeff is the son of famed forester of North Carolina Bob Zahner, for whom one of the Torreya seedlings planted in 2008 on the Waynesville property was named.)
A DEEP-TIME PERSPECTIVE ON WHAT IS "NATIVE"
From the very beginning, a symbiotic working relationship between Torreya Guardian activists and the professionals who are bound to abide by the specifications of the Endangered Species Management Plan for Torreya taxifolia has been thwarted, largely because of a disagreement about what constitutes "native" range and "native" habitat.
So long as the professional botanists and ecologists in charge of endangered species continue to assume that "native range" is limited to where these species were living when Europeans first arrived on this continent, mutually beneficial coordination of activities will be difficult to achieve.
In this time of rapid climate change, we simply must acquire a deep-time perspective. We've got to look at the migratory patterns of species and habitats with eyes that honor the flow of biological history not just human history. It is time to begin thinking about "native range" over the genus and species' entire biological lifespan. That means in thousands and millions of years, not just a few centuries.
To move weedy plants from one continent to another is, unquestionably, ill-advised. But moving a native and highly endangered conifer tree a few hundred miles northward on its home continent should be even less controversial than helping the California Condor re-establish nest-holds on the Colorado Plateau where it lived only in prehistory. (See the 2008 paper by Jillian Mueller and Jessica Hellmann, "An Assessment of Invasion Risk from Assisted Migration".)
See also the comments filed by Connie Barlow in 2010 re the USF&WS request for comments on the proposed update of the ESA Management Plan for Torreya Taxifolia. She subtitled her comments, "An Opportunity to Shift to a Deep-Time Perspective of Native Habitat." See also this short-version, illustrated webpage: "Paleoecology and the Assisted Migration Debate: Why a Deep-Time Perspective Is Vital."
Finally, although portions are now outdated, see the original paper that launched the debate in 2004, co-authored by Connie Barlow and (the late) Paul S. Martin: Bring Torreya taxifolia North Now."
THE APPALACHICOLA HABITAT AS GLACIAL REFUGIUM
Palynologist Hazel Delcourt, in her 2002 book, Forests in Peril: Tracking Deciduous Trees from Ice-Age Refuges into the Greenhouse World, has well established that the Apalachicola region of the Florida panhandle is one of a handful of primary "pocket refuges" along the Gulf Coast and the southern Atlantic to which the rich flora of the central and southern Appalachians retreated during the peaks of glacial episodes. Indeed, it can be reasonably inferred that had this continent lacked such large riverine environments with banks of rich soil (contrasting to the predominant sandy soils of the region), North America would have lost to extinction genus Liriodendron (tuliptree) as did Europe.
The MAP (left) shows the primary watercourse routes that rich-soil and moisture-loving species of America's eastern deciduous forests would have taken to find refuge during peak glacial times. The "Alatamaha" refugium would have extended out onto the continental shelf of the Atlantic side of Georgia, when ocean level was at a low because of all the water bound up as glacial ice. It was along the lower Alatamaha that the only specimens of the nearly extinct Franklinia shrub species were ever found.
It is plausible that Torreya taxifolia once took refuge along the lower Alatamaha, but it has never been seen there in historic times. Its only "historic" sightings have been at or near the Appalachicola River (marked in orange on the map) which served as another key glacial refugium for temperate species of eastern North America.
CONCLUSION: The best explanation for why Torreya taxifolia is now endangered is not that it is poorly adapted for continued existence in eastern North America after a legacy of millions of years. Rather, the eastern species of this Northern Hemisphere genus is a glacial relict in its current location. It was "left behind in near time," in its ice-age refugium, according to the late Pleistocene ecologist Paul S. Martin. Observe (left) that the large seed would have required squirrels (who extract and bury the seed) to help this species move in tandem with climate change. Paul Martin and Connie Barlow surmised that, because the Apalachicola refuge habitat was so limited, and because the riverine habitat would have been so attractive to the first peoples 13,000 years ago, the local squirrel population may have been extirpated, thus depriving this species of an animal disperser. Hence, the call today for "assisted migration" to help this conifer quickly sync with a warm, interglacial climate.
Map of how rising sea-level at the peak previous interglacial period (Sangamon Interglacial, 125,000 to 75,000 years ago) would have forced the coastline of Florida to recede. Where would have been "native range" for Torreya taxifolia during that time and where should it be today?
Source: Rachel Carson, The Edge of the Sea, 1956 (p. 195). On the facing page to this map, Carson wrote, "To understand the living present, and the promise of the future, it is necessary to remember the past."
A. J. Bullard with his Torreya taxifolia in Mt. Olive NC, which he planted from a seedling from the mother Torreya in Clinton NC.
Squirrels are repulsed from stealing unripe seeds still hanging on the tree; the branches are too long, the leaves too prickly, and the seeds borne too far out on slim branches for any squirrel to access. Rather, squirrels have to wait for seeds to fall to the ground when ripe.
This contrasts with seeds produced at the Atlanta Botanical Garden from specimens that began as rooted cuttings from branches of wild Apalachicola genotypes. Those branches retain a "memory" of being on a much older tree; even though they were cut and rooted as the new main stem of a growing individual, they retain a shrubby stature and tend to produce seeds more than a decade earlier than a Torreya tree germinated from seed.
CALLING FOR PROFESSIONAL AND ACTIVIST COLLABORATION
Overall, the pattern of success and failure resulting from even these first 4 years of fieldwork by Torreya Guardians offers important guidance for homing in on preferred habitat specifications for North America's eastern species of Torreya under the climate conditions that prevail today (and as projected into the future).
Site visits, consultation, and further experimentation northward of the species' glacial refugium are highly recommended toward coming to understand the preferred habitat and the survival/thrival boundary conditions of North America's eastern species of genus Torreya the only endangered species of genus Torreya in the world. Thus far, it is the activists within the Torreya Guardians collective, and the private landowners they work with, who are in the lead for doing the actual fieldwork by which to best discern the species' habitat preferences under today's climate conditions (and with an eye to how plants zones may continue to shift over the course of even a single generation of trees assisted in migrating). See how much the zones have already shifted, as indicated in the February 2012 release of a new plant zone map for the USA by the US Department of Agriculture.
Observational work and conjectures in the tradition of "natural history" will continue to be highly useful. Professionals and avocational volunteers with broad experience are both needed for formulating hypotheses for rigorous testing, while field testing and assisted migration continue.
Qualitative assessments and tentative conclusions will also continue to be necessary, especially in assisting private landowners who wish to abide by current best practices in how best to aid this species in migrating to habitats that today (and in the future) will offer its best prospects.
By discerning Torreya's preferred habitat conditions and doing our best to plant seeds and seedlings in such habitats, we will be giving the tree a chance to use its natural defenses to thwart Phytophthora water molds (and other plant diseases) that have already destroyed its reproductive capabilities in its historically native habitat (northern Florida).
It thus will be humans who help the species to "migrate" northward, but it will be up to the species itself as to whether "colonization" is the long-term result. This is a hugely important distinction. By experimenting with possible habitats well northward and altitudinally higher of its "historically native range," we Torreya Guardians are aiming for results that will enable species preservation without the need for continuing taxpayer support. In contrast, so long as the ESA management plan limits Torreya restoration to the region best understood as its peak-glacial refugium, there is little realistic hope that the species will ever be restored to independent viability. See the online post: advocating the term "assisted migration" and the communications with scholars upon which it is based.
"My personal and professional odyssey as a historian of deciduous trees
has brought me to the realization that the future of the eastern deciduous forest is now at risk.
We can provide corridors to allow for species to migrate successfully
in the face of climate change. We may also need to be prepared to transplant
endangered species to new locations where climate will be favorable."
Forests in Peril (2002, pp 97, 207)
Hazel Delcourt Torreya tree with Sara Evans (left). Henry Thoreau with Janet Manning (right).
Photos April 2013 by C Barlow.
Return to HOME PAGE
Contact: conniebarlow52 at gmail dot com