7500 american chestnut trees and counting, the research that ate my summer in 2015. presented at...
TRANSCRIPT
7500 American chestnut trees and counting, the research that ate my
summer in 2015
NENHC 2016
April 2016
A copy of this presentation along with other research can be found at:
http://www.slideshare.net/rtgardner3
Abstract
During the summer of 2015 in reaction to the questionable concept I continually heard about the American Chestnut (Castanea dentata) going extinct I decided to do a census of the American Chestnut on the Appalachian Trail from the Rausch Gap to the Lehigh Gap and other local trails. Over 38 days were spent on the census using a GPS equipped camera with many more days gathering data on American Chestnut reproduction and how the Chestnut Blight (Cryphonectria parasitica) affected the trees. A total of over 80 miles of Appalachian Trail was walked along with at least another 40 miles on other trails. More than 7500 trees of various sizes from seedlings to mature adults were found along two trail systems separated by about 25 miles. In three separate locations a total of forty-four trees were found bearing seeds. The limiting factor in American Chestnut reproduction was clearly shown to be access to direct sunlight, not disease. The obvious conclusion derived from this time in the field is that the American Chestnut is coming back without our interference. Attempts to hybridize it with non-native chestnut species to make “blight resistant” trees are unnecessary and is detrimental to the ecology of the Appalachian forest. This study will be continued in 2016 by walking additional trails.
This study was conducted throughout the spring, summer and fall of 2015 with additional data from
spring 2016.
The American Chestnut Federation: proudly tinkering since 1989. Still clueless.
Me: walking for one year. Issue resolved.
The American Chestnut is not a problem to be solved but rather a fascinating study in a human mediated ecological disaster and the biological
response.
The ecological damage which the American Chestnut Federation can cause is due to:
• a lack of study and understanding of the Eastern Forests,
• inherently flawed paradigms about how natural systems function and how human interference
can cause them to function “better” and
• the common human almost demonic drive to tinker.
As an ecologist I continually see where introductions of magic bullet plants to solve
non-existent ecological problems cause problems: Sawtooth Oak, Russian/Autumn
Olive, Multiflora Rose, Chinese Lespedeza and etcetera.
In Invasive Plant Ecology we have the Enemy Release Hypothesis.
In part, this states that an overwhelming number of native organisms cannot use
introduced non-native plants because they did not coevolve together.
Hybridizing a native plant with another native or especially a non-native creates a non-native
plant of little or no ecological utility.
Therefore, changing the gene structure of a native plant by hybridizing with a non-native in
hopes of improving/saving the plant from introduced diseases or pests is doomed to be an
ecological failure because few if any native organisms using the native plant will be adapted or adapt to use this hybrid due to changes in the
physical and chemical properties of the plant.
We do not want to do this in ecology because it destroys the plant’s ecological utility as a food
source, etcetera.
Along with this my thinking is that native organisms require high genetic heterogeneity
within the species utilized to match the variation in native organisms utilizing them.
Limiting the phenotypic diversity by reducing the sources of genetic material limits the
number of species and heterogeneous individuals within those species which can utilize
a particular plant species.
And, it is hard to conceive how hybridizing one plant with disease susceptibility with another plant susceptible to the same disease makes a
disease resistant hybrid.
Simply put:
No matter how successful the hybridization appears to be it is an ecological failure.
“The operation was a success, but the patient died.”
Cleora sublunaria on a mature C. dentata tree, April 19, 2016
It is better to patiently study the system to understand what is happening and determine if
the apparent crisis is a real crisis.
If the crisis is real, then develop strategies which have minimal or no ecological impact such as
looking for resisting/resistant plants.
In the case of the American Chestnut, the answer was always there, but those with power
never looked for it.
7,551* American Chestnuts total were found in the spring, summer and fall 2015 on two sets of trails
separated by @ 25 miles at their closest.
*If there was 6” or 8 “ between stems in a cluster unless obviously a clone, the stems were counted as separate trees. This is in line with the concept that animals such as squirrels and corvids made non-recovered caches of seeds which produced
multiple trunks in the same location.
7,251 American Chestnut trees found on the Appalachian Trail and related trails from Rausch Gap
to Lehigh Gap, @ 80 miles linear distance.
118 American Chestnut trees found on trails in the Birdsboro Reservoirs area in a quick incomplete
survey to confirm data from the Hamburg Reservoir area of the Appalachian Trail. (182 trees found at
French Creek, a related trail set, but unrelated study.)
Maryland Delaware New Jersey
our home
Appalachian Trail study area 7,251 C. dentata trees
Downloaded from Google Maps 4/2/2016
Birdsboro and French Creek study area 300 C. dentata trees
25 miles
New York
www.google.com/maps Mar. 9, 2016
Appalachian Trail on Blue Mountain
Birdsboro Reservoirs and French Creek State Park
@ 25 miles between points
our home
Molasses Hill Lake Ontelaunee
Middle Creek Wildlife Management Area
Mt. Penn
Expected locations of American Chestnut trees
Hamburg Reservoir
Known groves of American Chestnut trees
Second and Sharps Mountains
Copied from Google Maps on Mar. 2, 2016
Topographical map showing distance between Blue Mountain and the Birdsboro Reservoirs/French Creek State Park with other relevant information
Appalachian Trail
Rausch Gap
Lehigh Gap
Birdsboro Reservoirs and French Creek State Park
Left to right, top: Dauphin, Schuylkill and Carbon counties; bottom: Lebanon, Berks and Lehigh counties
Non-native Chestnut
Lehigh Gap
Rausch Gap
Blue Mountain: Rausch Gap to Lehigh Gap 2015 chestnut survey
Hamburg Reservoir
Dan’s Pulpit
Allentown Shelter
Roundhead
yellow indicates C. dentata groves
Lehigh Valley Nature Center
One of the two most interesting discoveries is that the Appalachian Trail is a refuge and a corridor for the
spread of the American Chestnut tree.
Other trails in Pennsylvania such as the Mason Dixon, Conestoga, Mid State, Brandywine River,
Bartram and Laurel Highlands probably serve the same purpose. I will exploring sections of these this
summer.
Another apparent correlation is that wider parts of the AT and other trails serve as a corridor for the local spread of the trees in that they provide an easy “low friction” route for birds such as blue jays to fly along,
turkeys to run down and small mammals to use.
This needs more work as it was not an absolute correlation, but an apparent one.
Extrapolating from a reference*, crows during the fall migration may be spreading seeds along the ridgeline
the AT uses locally.
*American crow http://bna.birds.cornell.edu/bna/species/647/articles/migration
Fall migration
Over the length of the AT, the apparent southward spread of seeds during the fall crow migration and
northward spread of pollen during the spring pollinator migration are two of the most important
ways for the American Chestnut to maintain its genetic heterogeneity. As part of this process disease resistance genes spread between groves and widely
spaced trees.
Pollinators and crows – maintaining genetic heterogeneity and spreading disease resistance along Blue Mountain
Pollinators move pollen north during spring migration as the trees bloom
Crows move seeds south during fall migration
tree
nut
Within a set location, the seeds are spread by rodents such as red squirrels, gray squirrels and
corvids such as blue jays.*
*Heinrich, B. 2014. American Chestnut Seed Dispersal and Regeneration. Northeastern Naturalist 21(4):619-628.
Heinrich, B. 2014. American Chestnut by Red Squirrels. Northeastern Naturalist 22(4):N19-N23.
tree
Seed spread by blue jays with red and gray squirrels
squirrels
blue jays
This is part of the process of basic Darwinian evolution – the more resistant trees reproduce at a higher rate because they are healthier than the less resistant. (Eventually, the less resistant tree lineages go extinct by continually losing the competition for
sunlight and other resources.)
Diseases and pests such as Bacterial Leaf Scorch (Xylella fastidiosa), Emerald Ash Borer (Agrilus
planipennis), Gypsy Moth (Lymantria dispar dispar) the Hemlock Wooly Adelgid (Adelges tsugae) and the Elongate Hemlock Scale (Fiorinia externa) are opening
up the canopy.
Which means the American Chestnut may soon again become the dominant tree in our eastern hardwood forests as trees mature and reach the forest canopy.
Diagrams of how I think the American Chestnut and how its genes are being
spread.
gypsy moth larva
gypsy moth laying eggs
elongate hemlock scale hemlock
wooly adelgid
Trees
Seedlings
AT north of Auburn Overlook
tree from AT north of Auburn Overlook transplanted at home
Sand Spring trail near Shartlesville
AT south of Lehigh Gap
Disease
The Chestnut blight was found in Brooklyn, NY in 1904. It spread to Pennsylvania a few years later.
When a tree becomes infected and a trunk dies it fights back by coppicing, sending up new shoots from the top of the root crown to produce multiple trunks.
(Multiple trunks appear to be a common growth habit among some trees in our area such as silver maple. This may be a common defense against disease and
other injuries.)
Castanea dentata
Acer saccharinum
One question which needs resolving is the difference between multiple trunks from nut
caches vs. coppicing from disease. The following two photos are most likely due to caching.
Castanea dentata
Quercus alba
Trees show lack of disease resistance in all age classes and stem size.
Multiple areas of infection are common on mature trees. Besides American Chestnuts this pattern was found locally on oak, choke cherry,
birch and other species.
Disease on American
chestnut. Castanea dentata
Disease on American chestnut
trees, Castanea dentata
disease on red oak trees, Quercus rubra
disease on black birch tree, Betula lenta
disease on choke cherry, Prunus virginiana
disease on white birch, Betula papyrifera
disease on silver maple, Acer saccharinum
Flowers
The second important discovery this past summer is that the limiting factor in tree reproductive success is
not the Chestnut Blight (Cryphonectria parasitica), but rather access to direct sunlight on the apical ends
of branches.
All mature trees which received direct sunlight had flowers, burrs and nuts.
Chestnut flowers are a good source of nectar and pollen for insects such as bees at a time before many non-tree flowers bloom. This gives pollinators early
season flowers to feed on as part of a continuous food supply from mid-spring to frost.
Burrs and Nuts
Despite the blight, the trees are surviving to reproduce.
• 46 trees have burrs in several distinct locations along the areas of Blue Mountain surveyed.
• 40 of these trees are between Rt. 183 and Port Clinton
• 1 is on the Appalachian Trail on the top of the ridge at the northern edge of the Hamburg reservoir watershed
@ 600 yards left of Gold Spring,
• 1 is on a trail near the Berks County highest point,
• 3 are near Round Head and the old AT and
• 1 is on the south side of the Lehigh Gap just north of the AT.
Two trees near home which produced burrs in 2015. Left Berks County, PA highest point trail lat. 40:31:15 long. -76:14:47 DBH:10.3” Height: @34 feet Right Hamburg Reservoir, Appalachian Trail in PA lat. 40:36:20 long. -75:56 :51 DBH:7.0” Height: @36 feet
3 feet between orange tape and tree base, 6 feet
between green tape and tree base
Location: Berks County, PA on the trail to the highest point in Berks county, SGL80, lat. 40:31:15, long. -76:14:49 DBH = 10.3” Height: @ 34 feet
3’ between green and orange tapes x 2 = 6’ between green tape and base of tree
Location: Hamburg Reservoir, Appalachian Trail in PA, lat. 40:36:20, long. -75:56 :51 DBH = 7.0” Height: @ 36 feet
Location: Berks County, PA, Rt. 183 north, SGL110, lat. 40:32:22, long. -76:10:21 Chestnut cluster # 1, 3 trees, DBH L to R, 7 trunks total Tree 1 = 4.8”, 3.0” Tree 2 = 3.3”, 5.7”, 6.5” Tree 3 = 5.3”, 5.9” Height: tree 1 = @ 38 feet, other trees not calculated
Location: Berks County, PA, Rt. 183 north, SGL110, lat. 40:32:21, long. 76:10:23 Chestnut cluster # 2, 2 trees, L to R DBH Tree 1 = 7.1” Tree 2 = 7.3” Height: @ 30 feet, 32 feet
Location: Berks County, PA, Rt. 183 north, SGL110, lat. 40:32:21, long. 76:10:25 Chestnut cluster # 3 DBH = 6.2” Height: @ 36 feet
40 trees with burrs Rt. 183 north to near Port Clinton
Port Clinton
Rt. 183
Burrs appear to open just after rain.
Rain swells the burrs causing them to open.
Burrs appear to open on both the tree and the ground. Open burrs on trees can become food for crows, blue jays and squirrels. On the ground they
can be food for mice, chipmunks, squirrels and turkeys.
Wet soil makes it easier for corvids and rodents such as squirrels to cache nuts in the ground which
enhances germination success.
Swelled burrs are soft from the absorbed moisture which makes them a good food source for bacteria,
fungi, protists and insects – moist, nutritious, easy to burrow in and easily digestible.
This allows the nutrients in the burr to be swiftly recycled into the soil while creating a community of organisms which benefit from the tree while giving
benefit to the tree.
Benefits to the tree may include increasing disease resistance, lowering the load of pathogens and
predators near the tree, moving nutrients into the soil close to the tree, etcetera.
Nut dispersal
Nuts in burrs had 3 basic shapes: spoon shaped (spatulate), egg shaped (ovate) and house
shaped (truncate).
Most burrs had 3 nuts, often 1 ovate with 1 spatulate on both sides or a mixture of spatulate
and truncate shape.
wt. (g) height (cm)
width (cm)
thickness (cm)
3.7 2.2 2.0 1.4
Average dimensions of seeds dehisced on their own
wt. (g) height (cm)
width (cm)
thickness (cm)
3.5 2.1 1.8 1.5
Average dimensions of seeds manually dehisced
The following is measurements of the egg shaped (ovate) seeds.
*No measurements were taken for the other shapes.
Path forward:
2016 1. finish survey in the Birdsboro/French Creek areas
2. extend the ends of the survey to the Susquehanna River and the Delaware River
3. survey other relevant trails within 90 minutes of home 4. start looking at reservoirs to find fruiting trees as they
should have more open areas than trails 5. continue looking for seedlings in danger from trail
maintainers and hikers to transplant at home 6. continue collecting nuts to grow at home
7. identify and document pollinators and other nectarivores on American chestnut flowers.
I plan to use a quadcopter (drone) with camera this year to better understand and document what I see.
Our ultimate goal To grow 2 successive generations (F2 generation) of burr bearing American Chestnuts from seeds in our
yard.
Anyone who wants to join me is welcome to grab a camera, their shoes, a day pack and do so.
Walk more
Tinker less
Richard Gardner
410.726.3045
http://www.slideshare.net/rtgardner3
Addendum
Miscellaneous thoughts on how American Chestnut seeds are spread.
tree
physical factors – steepness of slope, texture of ground (smooth, rough, boulders, duff, trail), proximity to and type of water way (ephemeral, intermittent and perennial streams), wind, other trees, density and size of understory plants
ephemeral/seasonal/intermittent stream
perennial stream
smooth trail
rough ground – boulders and logs
trees and shrubs
tree
squirrels, chipmunks and other small mammals – distance nuts are moved from tree depends on size of mammal, the larger the mammal the further the nuts are moved
Small animals such as mice
Medium sized mammals such as squirrels
Larger mammals such as raccoons
tree
birds – distance nuts are moved depends on size of bird, primary type of movement, migration patterns, …
Crows depend on whether migrating or in home territory
Turkeys on trails and through the woods, primarily on foot
Blue jays through the forest to roosts and perches
Non-native Chestnut
