Connecticut Chapter, The American Chestnut Foundation - Research

Chestnut Flower Season is Here

Wed, 02 Jun 2010 10:12:00 -0700

If you have any new info on the blooming status of trees you are checking, please let us know soon. Please count if the tree or tree cluster has at least 25 blooming tips - hopefully averaging 2 or more females per bag if 25 bags placed. A full line on the first try is our goal. For completing a line we could consider one with fewer tips, but remember it's very expensive for companies to send a truck, would like the probability of harvesting the full balance needed to finish the line.

Bagging may start during the week of the 13th. With the warm weather it appears the season is coming on very fast - much earlier than last year.

We're checking if additional bucket truck companies may be available, so knowing which towns helps with the request. Please consider helping on site. We can send out bags, ties and markers to number the bags, you would need pruning shears (although the truck arborist usually has his/her own). There are resources on our websites about timing and what to do. Some low growing trees may be able to facilitate a successful ground based bagging, please be careful. Keep in mind that the bucket truck companies need advance notice of at least a few days to schedule their trucks.

Gayle Kida
The American Chestnut Foundation®
CT Chapter Tree Breeding Coordinator
Gayle7258gk 'at' gmail 'dot' com

[click for larger photo]

Tracing American chestnuts with chloroplast DNA markers

Thu, 18 Feb 2010 19:32:00 -0700

By Kendra Gurney
TACF® New England Region Science Coordinator

In spring of 2009 Dr. Fenny Dane, a professor at Auburn University, presented her research on the evolutionary history of Castanea species at CT-TACF's Annual Meeting. Dr. Dane has used the DNA of chloroplasts, small organelles within the plant cell, to trace populations of Castanea species over millions of years. The study of chloroplast-DNA is a common tool for plant scientists interested phylogeography because the DNA of the chloroplast is effectively haploid (only has one set of chromosomes) and inherited maternally. This provides the ability to trace seed-mediated migration and colonization of plant populations over time. Differences in chloroplast DNA can be used to designate haplotypes, or different genetic lineages. It has been shown that each Castanea species has several distinct chloroplast types. More differences can be detected among Asian species than within European or North American species using chloroplast DNA analysis. Dr. Dane hypothesizes that the genus originated in Asia, migrated to Europe and then continued west to North America. From an analysis of samples from the Appalachian range of the US we can hypothesize that Castanea found refuge in the southern region of the Appalachian Mountains during glacial periods. Following the retreat of the ice sheet, one lineage, the C. dentata D1 haplotype, migrated in a north-easterly direction. Much of Dr. Dane's work with Castanea in North America has focused on samples from the southern and central Appalachians, where more diversity in chloroplast type has been detected. Dr. Dane suggested that it would be helpful to her work if the CT Chapter could provide her with samples of genetic material from known, validated Castanea dentata (American chestnut) examples from Connecticut. Currently, such specimens are validated by scientists who use a dichotomous key to analyze a sample for traits indicating C. dentata lineage. Positive validation leads to the selection of mother trees appropriate for inclusion in the CT chapter's breeding program. Analyzing the chloroplast DNA of validated C. dentata samples from CT would benefit Dr. Dane's work by providing more samples to support the single north-easterly linage hypothesis. Such an analysis would also benefit the CT Chapter, by verifying that the current process of sample validation for selecting mother trees is in fact identifying pure C. dentata from the local population. This past summer, CT Chapter President Bill Adamsen took on the task of collecting samples for Dr. Dane from the chapter's mother trees, as well as the backcross offspring that have been produced. His total journey was just over three hundred miles and he collected a total of collection totaled thirty five mother tree samples and twelve orchard back-cross samples. Thirty three of those samples collected were submitted to Dr. Dane (some samples were omitted because of collection timing issues) and the results are in! Her graduate student, Xiaowei Li, isolated DNA from the leaf samples and amplified small sections of the chloroplast genome using the polymerase chain reaction, followed by sequencing analysis. All samples showed the C. dentata D1 haplotype, most commonly detected in populations of the American chestnut (see Figures). This means that all samples are from the linage that travelled north-east following the retreat of the ice sheet. The analysis cannot pin-point the origin of the trees any further, but does provide evidence that the mother trees used in the CT Chapter's breeding program are, in fact, Castanea dentata, or American chestnut, which is a nice validation of the careful selection process used. For more information see: Dane, F. 2009. Comparative phylogeography of Castanea species. Proceedings of the Fourth International Chestnut Symposium. Acta Horticulturae 844: 211-222.

Home page of Fenny Dane at Auburn Article by Kendra Gurney
The American Chestnut Foundation®
New England Regional Science Coordinator
USFS Northern Research Station
705 Spear Street
South Burlington, VT 05403
Tel: 802.951.6771 x1350
Cell: 802.999.8706
Kendra@acf.org

TACF Tree Web Application

Tue, 09 Feb 2010 12:34:00 -0700

By Bill Adamsen - Wilton, CT
Director of The American Chestnut Foundation, President, CT Chapter

The American Chestnut Foundation (TACF) has embarked on a major initiative to bring its tree data closer to the end user by developing a web-interface on a database application. The solution is expected to allow members and constituents to use on-line forms to provide observation data on wild trees, orchards, and restoration plantings. Outside collaborators can create experiments and analyze metrics for success by leveraging internal algorithms such as coefficients for kinship and inbreeding to help define optimal pedigrees. The goal is to support the efforts of TACF to develop a blight resistant American chestnut through a traditional plant breeding program. [More]

Chestnut and Invertebrate Extinctions

Sat, 12 Dec 2009 11:19:00 -0700

By Bill Adamsen - Wilton, CT
Director of The American Chestnut Foundation, President, CT Chapter

A few weeks ago I had the chance to speak to Dr. David Wagner at the University of CT about the functional extinction of the American chestnut and he commented with an anecdote I'd not heard before. He pointed out that the functional extinction of the American chestnut accounts for a significant percentage of the recorded invertebrate extinctions in modern times. In fact Dr. Wagner provided this qualified quote ...

“American chestnut extinction correlates to the greatest invertebrate extinctions on earth in the modern era. That there are only 61 invertebrate extinctions in modern era ... 41 in North America and of those, 5 are directly related to loss of chestnut.”
Dr. David Wagner

The five insects believed to be extinct as a result of the chestnut's demise (see the IUCN Red List) are Argyresthia castanella, Ectoedemia castaneae, Ectoedemia phleophaga, Tischeria perplexa, and Swammerdamia castaneae. In fact, seven are (were) red-listed as extinct but two of those - Synanthedon castaneae and Coleophora leucochrysella - have been subsequently found by Dr. Wagner and his team. While the specifics are probably important, the general concept is truly monumental. Loss of a single species in an isolated ecosystem can have dramatic and unanticipated effects. In the most recent publication of the Annual Review of Entomology, David Wagner and Roy G. Van Driesche discuss some of the threats to rare insects by invasive species and the evidence is telling .

Since its discovery in Michigan in 2002, the Chinese buprestid Agrilus planipennis has killed more than 30 million ash (Fraxinus) trees in the northcentral United States (43, 122). If ash suffers the same fate as American chestnut (Castanea dentata), numerous Fraxinus specialists will perish. Wagner (168) identified 21 ash-feeding moths and butterflies potentially threatened by the beetle, of which five sphingids--Ceratomia undulosa, Manduca jasminearum, Sphinx canadensis, Sphinx chersis, and Sphinx franckii--are thought to be especially vulnerable.
Annual Review of Entomology 2010 55:565

This is a good reminder of the complexity of our ecology and the impact of a single foreign invasive pathogen. A bird lover, I always wonder how insect abundance affects birds. There is of course much more to the puzzle. If you have comments or other examples, please feel free to put them in the comments below.

Pre-Blight Chestnut Mast Estimates

Sat, 05 Dec 2009 02:43:00 -0700

By Bill Adamsen - Wilton, CT
Director of The American Chestnut Foundation, President, CT Chapter

Several months ago a friend sent a link to an article which provides evidence that chestnut really was a dependable source of food for wildlife - something frequently mentioned - but without documentation. After reading the article Hard Mast Production Before and After the Chestnut Blight I thought more CT Chapter members might appreciate the opportunity to read it. It provides a comparison of estimated hard nut production in a Southern Appalachian forest that happened to be assessed carefully at the time of the blight, for hardwood composition. The immediate impression the article had on me - was realization of the impact the loss of a high volume producer (chestnut) must have had on wildlife. Looking at the graph below (or reading the referenced article) one is struck by how dissimilar the large year-to-year variability in mast production among oaks is to chestnuts (the bright green section on histogram bars to left). The loss of American chestnut must have greatly increased mortality for many mammals and birds which would have depended on the stable and consistent food supply chestnut provided.

The below graph uses the data provided in Hard Mast Production Before and After the Chestnut Blight to display calculated total hard mast production for a 10 yr interval in a Coweeta Basin forest before and approximataly 35 years after the chestnut blight epidemic.
All data by Diamond, Giles, Kirkpatrick and Griffin
Graph formatting by Bill Adamsen

The publication is available on-line. The authors are Seth J. Diamond, Robert H. Giles, Jr., and Roy L. Kirkpatrick, Department of Fisheries and Wildlife Sciences, and Gary J. Griffin, Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute. Thanks to Leila Pinchot for forwarding the article.

Connecticut Forests in a Changing World ? from Global to Local

Fri, 13 Nov 2009 23:38:00 -0700

So is titled Connecticut's fifth Statewide Forest Forum. Be sure to look at the agenda and list of speakers - there's not a session you'd want to miss. Hope to see you there!

The 5th annual Connecticut Statewide Forest Forum will be held on Tuesday, November 24 at the University of Connecticut Rome Ballroom in Storrs. Complete details and registration information are attached, and are available at www.ctwoodlands.org. Connecticut's Forest Forums were created to enable anyone interested in forest resources, regardless of background or experience, to come together, share ideas and work towards solutions to our forest-related problems. Past Forums have highlighted such issues as forest sustainability in an urbanizing environment, blending science and policy, and valuing forest ecosystem services. This year, we build on these themes by looking at Connecticut in the context of critical global and national issues. A fascinating look at the complex and rapidly changing global forces shaping Connecticut's forests will be followed by an overview of national forest policy, including the 2008 Farm Bill and its impacts on Connecticut. We then turn to the state level and a new state forest resource assessment which is in progress as we meet. The results will produce a strategy to guide future use of state and federal forest funding. The morning concludes with a fresh look at forest ecosystem services, followed by ample time for questions. The afternoon begins with a roundtable session where participants can add their ideas to the developing statewide strategy and plan. Three concurrent sessions follow. The Private Forest Stewardship session delves into key current issues including climate change, carbon sequestration and details of the 2008 Farm Bill programs. Forest Research and Forest Health provide four reports on research underway in the Highlands of western Connecticut. Urban & Community Forestry is examined in the context of the latest Smart Growth initiatives and Connecticut's shifting political environment. The $50 registration fee includes all breaks, lunch and handout materials. Questions and suggestions may be directed to Steve Broderick, Forester and Program Director at the Goodwin Forest Conservation Education Center, at 860-455-9534 or sbroderick@ctwoodlands.org. We look forward to seeing you there!! Thomas E. Worthley Assistant Extension Professor Middlesex County Extension Center 1066 Saybrook Rd. Haddam, CT 06438-0070 phone: 860-345-5232 fax: 860-345-3357 2009 Forest Forum Brochure [1800kb]

Bill Adamsen President, CT Chapter of The American Chestnut Foundation

Chasing Chloroplasts

Wed, 30 Sep 2009 09:04:00 -0700

Professor Fenny Dane of Auburn University presented her Castanea Migration Theory at last year's CT Chapter Annual Meeting. Each Castanea species has several distinct chloroplast types. More differences can be detected among Asian species than within European or North American species using chloroplast DNA analysis. However from analysis of samples from the Appalachian range we can hypothesize that Castanea found refuge in the southern region of the Appalachian mountain range during glacial periods and that following the retreat of the ice sheet, one lineage migrated into north easterly direction. Dr. Dane had suggested that it would be helpful to her work if the Connecticut Chapter could provide her with samples of genetic material from known validated American chestnut examples we'd found in Connecticut. We keep accurate track of the samples and validation process, and by summer's end had twenty seven validated American chestnut that we had either successfully pollinated or felt had a high probability of flowering and providing an opportunity to pollinate. Validation is a time and resource consuming process whereby several scientists use dichotomous keys to analyze a sample for traits indicating American lineage. We use the same group of scientists - though it evolves over time - to ensure a consistent review. It should be noted that only a small percentage of the samples found in Connecticut are actually validated using this approach. The majority (about seventy-five percent) of samples submitted are rejected as being hybrids with Asian chestnut or European chestnut traits. And also, since it time consuming and resource consuming - we do not to bother validating samples of trees with known low probability to flower. So for instance, I'll see dozens of trees during a trail hike or canoe ride or even driving - but rarely bother to report the trees unless they look large enough to flower, with enough light, and accessible by bucket truck.

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[More]

Maps Showing Where You Might Find Chestnut in Litchfield

Fri, 12 Jun 2009 10:42:00 -0700

We've completed our predictive model for finding American chestnut trees in Litchfield County and now need your help determining whether this model works! Do you live in or visit Litchfield County? Print out one of these maps and tell us if you find an American chestnut tree while driving through one of the identified hot-spots. We have a fantastic prize for the greatest number of sightings. [More]

Chestnut Pollination Season

Thu, 11 Jun 2009 11:19:00 -0700

by Bill Adamsen

Achieving the goals set out in our regional adaptation program require finding native American chestnuts and capturing their genes. We do this by finding American chestnut that can be ...

a) validated as being pure American chestnut
b) cooperate by flowering
c) are accessible trees with accessible flowers
d) cooperate by being compatible with our advanced breeding pollen
e) have the vitality to survive till harvest with the number of nuts outlined as required

Even with this daunting list of requirements we have slowly yet surely been inching towards our goals as outlined in our strategic plan for capturing genes. [More]

Hunting the Elusive Flowering Chestnut

Fri, 05 Jun 2009 14:49:00 -0700

by Christine Cadigan

After a day of testing the hypothesis suggested in A Needle in a Haystack, I think our geospatial predictor hypothesis for chestnut may have merit. Those of you who read the article will recall that we used soil type, road proximity, sun aspect and other criteria to hypothesize a prediction model for spotting native American chestnut sprouts from a car. To test the model, I drove around the western part of Litchfield County near Segar Mountain Road and Skiff Mountain Road, locations with a high incidence of "hot spots" according to the model. . How did it work? I found only one reproductive tree, but I certainly found numerous sprouts! The results of my adventure include some additional ideas for tweaking the model and also some advice on methodology.

My first mission was to explore the Segar Mountain Road area (rt. 341). This section showed up on the map with perhaps the most significant number of hotspots for likely chestnut territory. This, as many of you may know, is a rather busy road and attempting to study the roadsides was nearly impossible.

As soon as I pulled over and shut down my car, I noticed a little chestnut sprout staring straight up at me (almost mockingly, really).
[click to expand photo]
Photo courtesy of Christine Cadigan.

Slightly frustrated at my inability to spot chestnut trees (let alone identify the species of any tree), I immediately pulled off onto a small side street to get out my map and regroup. As soon as I pulled over and shut down my car, I noticed a little chestnut sprout staring straight up at me (almost mockingly, really). After exploring this area for a while, I eventually chose to turn down another, larger side street that had several "hotpots" on it as well. Turning right on Kenico, I made a huge loop through Gorham to end up back on Segar Mountain Road. Where the loop turns into Gorham is most definitely chestnut territory. It's a previously disturbed area in very early succession stages?prime chestnut location. I saw several sprouts on this street as well, though none were reproductively active.

Sometimes chestnut is easy to find - such as this example providing irrefutable evidence of a previous year's flowering.
[click to expand photo]
Photo courtesy of Christine Cadigan.

The lesson learned for wannabee chestnut hunters is, it is highly recommend recruit an assistant chestnut hunter. I suspect it is far easier to drive and search with two sets of eyes. Either way, if you've found a potentially great area that straddles a larger, well-trafficked road, I would advise ignoring the map and pulling off on the first side street. Small shoulders on busy roads would not only be difficult for spotting chestnut, but would create havoc for a pollination team with a bucket truck as well. When finding chestnut to pollinate, considering logistics simply makes good sense.

Next stop was Skiff Mountain Road - which leads to my next bit of advice. The potential hotspots displayed on the map certainly do not take all aspects of chestnut ecology into account. Skiff Mountain Road is a fairly narrow, relatively undisturbed road with mature growth and very dense stands. There is not a lot of light coming through and large hemlock forests seem to shade out the possibility of chestnut. I, therefore, did not find very many sprouts on this road. My advice is to keep in mind those important facts about chestnut ecology when using this map. Especially when time is off the essence, I might advise eliminating shady, narrow roads from your list.

Other factors making chestnut spotting easier: key in on sunny spots (chestnuts thrive off of release; not to mention, it's far easier to spot them with a little light), choose side streets that may be less traveled, and don't be afraid to pull over and park if you've spotted a single sprout (chances are, there's probably a few more around too).

Good Luck!

Christine M. Cadigan
Candidate for Master of Environmental Management and Master of Forestry 2010
Nicholas School of the Environment
Duke University
Summer Intern - CT Chapter TACF

In every walk with nature, one receives far more than he seeks. -John Muir
[click to expand photo]
Photo courtesy of Christine Cadigan.

The Needle in a Haystack

Wed, 03 Jun 2009 20:06:00 -0700

Or ... how to improve our chances of finding native American chestnut
by Christine Cadigan

It's that time of year when we pull out all stops trying to find native American chestnut trees to pollinate across the native range.

A recent suggestion by CT-TACF member and Director Bill Moorhead has led to a full-blown attempt to make locating potential Chestnut trees easier for all chapter members. Specifically focusing in Litchfield County, several criteria were identified as optimal habitat for Chestnut trees. Based on historic sightings and pollinations, the most common soil type and moisture was inferred. It appears as though the highest frequency of Chestnut sprouts were found on Charlton - Chatfield complex soils which are very rocky and have a slope somewhere between 3 and 45 percent (classifications 73C and 73E). In addition, the sprouts appear to prefer dry-mesic sites. Based on this information, a geospatial analysis was conducted in order to determine potential hotspot of Chestnut sprout occurrences. The effectiveness of this method can only be verified by further sightings in the field. Therefore, it is the hope of this research team that this year's tree identifiers will use this map as a guide and will report back on success rates. [More]

A Thin Slice of Chestnut

Fri, 22 May 2009 13:53:00 -0700

Written by Bill Adamsen
CT Chapter of The American Chestnut Foundation
Yesterday a most unusual and welcome gift arrived in the mail. A micro-thin slice of American chestnut embedded between thin panels in a sandwich of glass, and described by its sender as a Magic Lantern slide. [More]

Evolutionary History of American Castanea species

Fri, 15 May 2009 20:51:00 -0700

Professor Fenny Dane, PhD
Department of Horticulture
Auburn University

[click to enlarge]
Figure 1. Distribution of vegetation on US continent
18,000 years ago during the last ice age

The geographical range and distribution of a plant species is dependent on its adaptation to ecological and environmental conditions and the distribution of the populations of trees, both in the past and present over the continents. In the case of Castanea species, the distribution has been especially influenced by the occurrence of ice ages during the Pleistocene and the susceptibility of especially the American chestnut species to chestnut blight. [More]

Visit to Aton Forest

Sat, 02 May 2009 17:11:00 -0700

By Sara Fitzsimmons
Regional Science Coordinator

The American Chestnut Foundation

On Saturday, April 25, several representatives from The American Chestnut Foundations (TACF) met at Aton Forest to discuss details of a summer project that is to be taken on by the Connecticut Chapter intern this summer. Christine Cadigan, a Duke University Stanback Intern, will be taking on this project starting in mid-May. More information on the intern and the project may be found at the related blog entry: Selection of Summer 2009 CTTACF Intern

[click to enlarge]
photo courtesy of Sara Fitzsimmons

The mature forest of Aton Forest contains primarily hemlock and red oak. This photograph to the left was taken along the township line, the westernmost boundary of Aton Forest. The main goal for this year's summer intern project is to discover the differences in chestnut counts between two sites, Aton Forest and the Harvard Forest. Dr. Fred Paillet, now at Univ. of Arkansas, saw many similarities between these two forests, but one major difference. While there were many living sprouts at Harvard Forest, Aton Forest had very few. What Aton did have, however, were many dead stems laying on the ground. Why would these two sites, with similar overstory, apparent geology, and general ecology, have such differences in chestnut stocking? And why would Aton, a site formerly rich in chestnut, no longer support living stems?

To answer those primary questions, Dr. Paillet has proposed a study for Christine wherein she will thoroughly 1) study the landuse and history of both sites; 2) sample dead chestnut stems as well as surrounding species; and 3) and map both living and dead chestnut locations. Differences in landuse may be the easiest answer. Different management techniques can certainly affect stocking of many species. Even if differences in landuse appear to be the primary answer, sampling and mapping of the living and dead stems can still provide very useful information. Christine, Dr. Paillet, and TACF can learn about what effects geology, soil type, slope, climate, and aspect all have on long-term chestnut population survival.

By looking at these sites closely, and determining why one site has sustained a living population while the other didn't, TACF may be in a better position to establish guidelines for long-term management of restoration plots. This living sprout (pictured in image to right) is along the North Colebrook Road, only a few hundred feet southeast from the main entrance to Aton Forest.

[click to enlarge]
photo courtesy of Sara Fitzsimmons

So, in preparation for Christine's arrival in mid-May, Dr. Paillet met with Dr. John Anderson, Executive Director of Aton Forest, Bill Adamsen, President of CT-TACF, Gayle Kida, Breeding Coordinator for CT-TACF, and Sara Fitzsimmons, TACF's Northern Appalachian Regional Science Coordinator (and former Duke Stanback Intern in 2000). The first thing we looked at were the only two living sprouts we knew about on the site as well as the only still-standing stump on the property. The photo to left shows another sprout found by Bill Adamsen during our walk. The larger stem is dead while the small sprout, being held by Fred, is barely visible.

And the only long-dead stem still standing. John is on the left with Fred in the middle. The cankered portion of this stem was removed and is now on display in the Aton Forest office.

[click to enlarge]
photo courtesy of Sara Fitzsimmons

[click to enlarge]
map courtesy of Sara Fitzsimmons

After looking at those individuals, the group traveled southeast to the township line, which is marked by a stone wall. From there, we traversed the contour of the slope. Below shows a draft map created using GPS coordinates taken during the tour. The living sprouts are in the upper portion of the map (marked by purple tree). The office is a big red phone. The dead stems are marked by green hexagons. Many other dead stems were observed but not sampled. The majority of those dead stems appear to be clustered up and down the south-facing slope. The "green cloud" near the living sprouts denotes an orchard of material from the Connecticut Agricultural Experiment Station.

One of the first tasks our group had to learn, and must subsequently teach Christine, is how to identify weathered chestnut wood. Chestnut wood is pretty distinct, though can be tricky until one gets a "seasoned" eye. But there are some good rules of thumb, and by the end of the day, the group were almost professionals at ID'ing downed stems.

[click to enlarge]
photo courtesy of Sara Fitzsimmons

The first feature of which to take note is what other species would be in the forest. In Aton, about the only species that could be large, downed wood would be white pine, hemlock, white birch, red oak, and chestnut. Each of those species are very readily distinguishable among themselves, except for red oak and chestnut. Hemlock and white birch typically decay quite quickly. White pine is highly distinguishable because it is not ring porous and should have a distinct "piney" smell for quite some time. When weathered, red oak and chestnut look very much alike and both have good rot resistance qualities. But there is one very noticeable feature difference between the two in a structure called a ray. When looking at a sample that might be chestnut, one should look very closely at the rings. On cross-sections of oak, like that to the left, red oak will exhibit very distinct white lines that bisect the growth rings. These structures are called "rays". While chestnut has these features, they are rarely noticeable to the naked eye.

Though sampling the dead wood as well as the surrounding living trees will be the only way we can determine the ages of these down stems, they have most likely been dead at least 60 or more years. Those stems in contact with the forest floor have decayed more than those stems that are up off the ground. But even those that endured for some time deteriorate more every year. The next decade or so may be one of the last opportunities for TACF to analyze the extent of pre-blight chestnut populations by sampling downed chestnut wood. Though very rot resistant, even chestnut will decay given enough time, and decay will only hasten as these stems fall to the ground.

[click to enlarge]
photo courtesy of Sara Fitzsimmons

Other Photos From the Forest

The tour provided great opportunities for seeing the early forest growth.

[click to enlarge]
photo courtesy of Bill Adamsen

[click to enlarge]
photo courtesy of Sara Fitzsimmons

Early this spring, Aton Forest experienced serious windstorms. The tops of many older white pine and hemlocks were sheared off the trees and strewn about the forest floor. One of the more interesting sights at the site is this blow-over of three mature hemlocks.

One of the more impressive parts of this blowdown of hemlocks is the very narrow band of organic material in which the hemlocks were growing. There is generally no mineral soil on this site and the bedrock tends to sit very near the surface.

[click to enlarge]
photo courtesy of Sara Fitzsimmons

Observations While Hiking in the Woods

Thu, 23 Apr 2009 09:01:00 -0700

Illustrations by Dr. Fred Paillet about American chestnut

Some of you may be aware that Dr. Paillet has been a major contributor to the training for the Appalachian Mountain Club Mega Transect project. Anyone who has read Dr. Paiilet's papers is aware that he is a master observer - one who draws meaningful inferences from details in the clutter of a forest floor. In recognition of this skill, and how it will be leveraged for this project, I've reproduced, with Fred's permission a series of his illustrations and accompanying descriptions of observations along some southern sections of the Appalachian Trail.

I am sure reading these notes has helped make me a better observer, and I hope it will do the same for you.

Figure 1 - [click to expand]
Illustration courtesy of Dr. Fred Paillet

Figure 1. Chestnut stump along the Appalachian Trail about two miles north of Springer Mountain, Georgia. This is the old stump of a blight-killed chestnut adjacent to an AT shelter, and is compared to a living chestnut tree in the same drawing. Based on tree-ring studies from the area, this tree was killed by blight sometime between 1935 and 1940. The flat top of the stump suggests that the tree was cut in the timber salvage operations typical of that era. Compare this stump to the base of a similar-sized living chestnut in West Salem, Wisconsin. That living and vigorous canopy-dominant tree had a dwarfed basal sprout growing from the suppressed buds on the root collar. A much larger population of living European chestnut sampled in Russia shows that these dwarfed basal sprouts are not unusual even when there is no damage or disturbance to the "parent" tree. Examination of chestnut trees killed by logging in West Salem showed these little sprouts grew from "bulbs" of tissue embedded in "sockets" in the root collar. A similar socket is clearly present in the old stump in Georgia, indicating that this tree also had one or more basal sprouts even before it was stressed by blight. Studies show that chestnut root collar sprouts develop their own root systems and are largely independent of the root system of the "parent" tree. These independent little trees have a very difficult time in surviving when they are isolated by a surrounding mass of wood, explaining why most living chestnut sprouts we see today originated as old seedlings that never attained large size. At the time this figure was made, sessile trillium and bloodroot were just bursting into bloom in the leaf litter along the trail.

Figure 2 - [click to expand]
Illustration courtesy of Dr. Fred Paillet

Figure 2. Chestnut sprout clone about one mile north of the AT crossing of US route 129, Neels Gap, Georgia. Most of the live chestnut sprouts observed along the AT looked like this. Sprout stems were small trees up to an inch or two in diameter and maybe 15 feet tall, occurring as single little trees or pairs of trees. They had clearly originated after a previous stem had been killed by blight, as indicated by the presence of old, deeply weathered wood from similarly sized stems. Almost all of the sprouts seen in April 2008 were recently killed by blight, or impacted by one or more active blight cankers. The incidence of blight is probably explained by the often-noted tendency for blight to occur in "epidemics". The basal sprouts produced by stems after they are girdled by blight remain small for many years. The numerous sprouts sort themselves into a small number as a result of blight, competition, and browsing. These remaining spouts are so small they provide very little substrate for the continued growth of the blight mycelia. The combination of a small "target" for the blight and the low level of blight in the area allows the regenerating sprouts to escape disease for a considerable time. The size of the stems in my figure indicate that this could be more than a decade. Eventually, the amount of chestnut bark available for blight infection reaches a point where a new epidemic can sustain itself, and the cycle continues. One wonders how many sprouts fail to make the transition under the stress imposed by blight and competition. A considerable number must be able to handle such adverse conditions because there are so many living sprouts today.

Figure 3 - [click to expand]
Illustration courtesy of Dr. Fred Paillet

Figure 3. Standing chestnut snag adjacent to the AT about two miles north of Neels Gap, Georgia. Although large chestnut trees in this area must have been killed by blight before 1935, some standing chestnut snags can still be seen along the AT today. In general, there is a wide variation in the state of preservation of chestnut logs and stumps along the southern part of the AT. The remains of the old chestnut forests vary from nearly intact snags such as in my figure, to badly deteriorated slabs of chestnut wood scattered in the leaf litter. The best preservation occurs when snags remain standing, or when fallen trees are propped up off of the ground by their lower branches. When chestnut logs are in contact with moist soil, they tend to rot out from the interior. The large vessels in the outermost sapwood keep the wood well-drained and free from decay. The inner heartwood has had the conducting cells plugged with resin, and this inner core of wood retains moisture and becomes more liable to decay. In time the log becomes hollow, and then the outer cylinder collapses to form a pile of slabs. This disintegration is aided by the lack of cross-connecting ray cells, which gives chestnut logs their well-known propensity to spilt into rails. But what kept the particular chestnut tree shown in my figure upright for more than 70 years? The location had something to do with it. This is a well-drained saddle in a ridge where the forest today is white oak, mockernut hickory, and basswood. Note that the snag is almost as big as the surrounding oaks, even though they have had another 70 years of growth. The leaning oak just behind the chestnut snag must have an interesting story to tell ? perhaps one of being blown over by a windstorm when no longer sheltered by the massive crown of the old chestnut.

Figure 4 - [click to expand]
Illustration courtesy of Dr. Fred Paillet

Figure 4. Dwarf chestnut tree attached to the stump of a large chestnut tree along the Sutton Bald Trail, Joyce Kilmer Wilderness, North Carolina. This is the exception that proves the rule. Most chestnut sprouts we see today originated as seedlings and were never attached to a large chestnut tree. When cut or damaged, chestnut trees produced abundant root collar sprouts. When free of competition, these spouts can produce new trees, even when they come from the stumps of former timber-sized logs. In the presence of competition and repeated blight damage, chestnut sprouts find a much more difficult situation, especially since the sprout root systems are not well connected to the tissue of the main tree, and must fend for themselves. The situation is even worse when the tree dies and is left standing. Chestnut wood is very decay resistant, so the aboveground part of the tree can last for a century. The roots are kept moist in the soil, and decay more rapidly. Thus, the tree eventually topples over under its own weight. Any little sprouts perched on the root collar are pulled out of the ground in the process. In this case, the stump is in the ground and the remains show that the original tree broke off above the root collar. In fact, the stump shows several stems as if the original tree was a coppice itself. I think of a storm-battered old chestnut clump on this exposed ridge. Sloughing branches and bark had been collecting for some time around the base of this clump of trees, forming a suitable substrate for the roots of the sprouts. The dwarfed chestnut sprouts that manage to live today show the continued rigors of life on an exposed ridge, but probably survive just because of those unusual conditions. Note how the shape of these stressed sprouts differs from that of most others, and that the small stems have the characteristic bark of mature trees.

Figure 5 - [click to expand]
Illustration courtesy of Dr. Fred Paillet

Figure 5. Vigorous chestnut sprout with fully healed hypovirulent cankers near the Wolf Laurel Trailhead, Joyce Kilmer Wilderness, North Carolina. Most of the chestnut sprouts seen today along the AT do not have the opportunity to become very large before blight cuts them down to size. Occasionally the fates decree that a combination of circumstances allow a chestnut sprout to reach substantial proportions. The tree in my illustration seemed perfectly healthy and had obviously been growing under almost full release. Death of a nearby oak had opened the canopy and this sprout clone was taking full advantage of the fact. Other chestnut sprouts in the area were being affected by blight, and this tree had a prominent blight canker on each of the three main stems. But the stems themselves showed no signs of stress. The crown was in the first stages of breaking bud, there were no basal sprouts being released, and no "water shoots" from the vicinity of the cankers. The cankers themselves seemed to have healed naturally, with a small patch of exposed dead wood surrounded by thick callous tissue. The "dead" oak associated with the release was cut in a logging operation some time ago. I think that the old piece of dead wood in the center of the sprouts was actually the stem released by the logging. This stem must have grown rapidly for perhaps a decade before being killed by blight. The canopy had still not closed, and so the basal sprouts stimulated by blight destruction of the main stem were able to grow under nearly full capacity. This process would account for the fact that the oak stump seems much older than the decade required to produce the chestnut stems we see today. Also note the recently dead chestnut stem off to the side. This is probably a sprout released with the three others, but left behind by the exuberant growth.

Figure 6 - [click to expand]
Illustration courtesy of Dr. Fred Paillet

Figure 6. Dense population of chestnut sprouts along a well-drained ridgetop, Slickrock Creek Wilderness, North Carolina. One of the often-noted characteristics of chestnut sprouts in our forests today is the tendency for sprouts to be clustered at particular locations. This is a typical example from the kind of clustering that was apparent at several locations along the AT in Georgia and North Carolina. This site was on the crest of a northwest-facing ridge dominated by dry oak-hickory forest with no identifiable remains of large pre-blight chestnut trees. None of the sprouts in the illustration appear attached to remains of larger trees, and all are assumed to have originated as "old seedlings". I have deleted all other small stems (sassafras, red maple, and spindly mountain laurel) from my drawing so that the six small trees in the figure are all chestnut. Only the tiny little sprout off to the right is unblighted ?an illustration of how small targets can escape the blight. The average spacing between chestnut sprouts here is about 6 feet. What accounts for such "hot spots" of chestnut sprout occurrence? Is this an artifact of seedling establishment, seed predator dispersal, protection from browsing, or differential survival from a much denser original population? If we knew the answer, we might have a real step forward in planning the re-introduction of chestnut to our forests.