The American chestnut existed
for approximately 10 million years
in the eastern hardwood forests of North America
and it provided numerous benefits
to wildlife species and other species
in the ecosystem and also was extremely
important culturally to humans for millennia.
The American chestnut, Castanea dentata,
was thought to historically constitute
3 to 4 billion trees in the eastern hardwood
forests of North America,
and approximately one quarter to one half
of the total tree density in forests where it grew.
It was so abundant that other
trees were actually named after it like
the chestnut oak, Quercus prinus.
The historical range of the
American chestnut was 200 million acres,
which is an area slightly larger than the state of Texas.
The chestnut’s range extended
from Maine south to northern Mississippi
and from the Piedmont west
to the Ohio River Valley.
The American chestnut occurred in over 40
different ecoregions and on a variety of site types.
Oak, which is like a cousin to chestnut
because it is in the same
taxonomic family, Fagaceae,
was the most common forest associate
with the American chestnut.
The best growth of chestnut
occurred in cove forests where
water was not limiting, but American
chestnut was most competitive and common
on intermediate side slopes and benches.
Historically and traditionally the
American chestnut was important for
lumber, and fuelwood, and tanning
in local industries.
It also was a very important food source
for southern Appalachian communities.
The American chestnut has almost a mythic
quality to southern Appalachian cultures.
Many folks that have lived
in the southern Appalachians,
remember American chestnut being
part of their family farm.
Family oral traditions are
passed down where they talk
about chestnut being on the
landscape and that they would
harvest chestnuts from them.
They would also use chestnut
for fence posts and lumber
for their barns,
and siding for their houses.
It’s almost woven throughout
their daily living experience.
[Stacy Clark] What’s it like to work with it?
[Eddie Hopps] It’s pretty nice. I didn’t even, I didn’t
even sand this. I just ran it because I
wanted it to be kind of rustic, so I just put,
I think two coats of clear on it.
It’s soft. It’s nice. Like I said,
it’s very similar
to ash in the grain configuration,
and I think probably because
of the patina on the wood,
it probably looks similar
to walnut, but it’s probably not,
when it was original, it was
probably not that dark.
The patina has darkened it
over the years being out in the weather.
Chestnut, without the worms, doesn’t
have much value.
[Stacy Clark] Right.
[Eddie Hopps] The wormy chestnut has a lot of value.
People, if they ever want to buy the
chestnut, they are going to want the
wormy chestnut.
In addition to the cultural significance
of chestnut, the species played a very
important role ecologically.
It was considered a ‘keystone’ species,
which basically means that
without this species, the ecosystem
would function very differently.
The American chestnut provided a stable
supply of hard mast in the fall by producing
nuts that were high in protein content
and fiber.
Species like black bear,
wild turkey, and white-tailed deer
consumed chestnut and even
preferred it over other hard mast
species like hickory or oak.
The American chestnut was probably a
consistent producer of mast because it
flowers later in the spring especially
compared to oak species.
Flowers typically formed after late
season frosts, which could damage
flower and mast production.
The effect that American chestnut had
on insect species, like the appropriately
named and now rarely seen
chestnut sawfly, is relatively unknown.
There is a lot we just don’t understand
about how American chestnut affected
food webs, wildlife habitat,
or other ecological processes
like roosting for bird and bat species
or soil, water availability and chemistry.
The first non-native disease that
negatively affected chestnut was root rot
caused by Phytophthora cinnamomi.
It arrived in the early 1800's,
probably from southeast Asia.
American chestnut shows little
resistance to this non-native pathogen.
Die-off of chestnuts and chinkapins was
noted as early as the 1850’s and 1860’s
in the Piedmont region
of the southeastern United States.
The disease causes roots
to atrophy and leaves typically
wilt and turn yellow prior
to the tree’s death.
Chestnut blight disease, caused by a
fungus, Cryphonectria parasitica,
arrived in the United States in the 1890’s
from imported Japanese nursery stock.
The disease was first reported in 1904
at the Bronx Zoo in New York.
The American chestnut did not evolve
with the blight, so genes
for resistance to this
disease did not develop.
By the 1950’s, chestnut blight disease
had virtually eliminated the American
chestnut throughout its range.
A tree that had existed
for 10 million years,
was wiped out in less than 60 years
by a non-native pathogen.
So you can see underneath the bark
it’s kind of dead and brown,
which means that it’s killing
the cambium layer of the tree.
If I go up here and cut into the tree,
you’ll see a very different color
because that’s healthy tissue there,
green and healthy.
Versus down here is brown
and very unhealthy, where the blight is
basically exuding that oxalic acid
into the tree that lowers
the pH of the tree and the tree
really can’t handle it and will eventually
the cells will start to die and eventually
the tree will be girdled completely around
the circumference of it
and the top will then die.
The chestnut blight enters the tree
through wounds and natural age cracks
that form on the bark.
Cankers then form on the tree
that often appear slightly
swollen around the margins
of the canker and sunken
in the middle.
The blight produces sexual spores
that are easily spread by wind
up to 6 miles, and asexual spores
are spread more locally by rain splash.
Spores are produced inside
orange-colored stromata that protrude
from the bark’s surface.
The chestnut blight cannot live
in the soil, so the American chestnut can
survive by sprouting from old stumps.
Sometimes these sprouts can live
for decades continuously dying back
and resprouting as they are infected
by the chestnut blight.
Occasionally an American chestnut will
live long enough to flower and bare fruit.
These trees probably have some low levels
of resistance or they have a blight strain
that is weak or hypovirulent.
These chestnut tree survivors provide very
important pollen and genetic resources
for restoration efforts that are
currently under way to breed
for resistance.
The chestnut blight is
ubiquitous and it cannot be contained.
It actually infects other tree species
like this scarlet oak, causing a butt
swell at the base of the tree.
However, the blight doesn’t kill
these trees.
So even if there are no chestnut trees around,
the blight can still be in the area on these
other host trees.
The chestnut blight is also
a saprophyte and it can live on dead
logs for a number of years.
Historical efforts to control blight
through cutting around
infected trees failed.
Control through chemicals like
fungicides are restricted
to small groups of trees
and are not practical on a large scale.
The chestnut blight brought one of the most
widespread ecological disasters ever
known, but forests have recovered.
The American chestnut was quickly replaced
by other species like oak, maple, and ash
to help form the forests we see today.
The effect of the demise of the chestnut is
not well understood.
Efforts to restore this
once iconic tree are underway.