Transcript Restoration and Invasive Species

Ecological Restoration (BIO 409)
Dr. McEwan
Invasion Ecology
The invasion process involves
three general phases…
Regional Invasive Species Pool
Proliferation
{
Dispersal
#1
Proliferation
Colonization
#2
#3
habitat space
Lag Phase
{
Colonization
Nascent Foci
Invasion & Other Processes:
- Invasion causes ecosystem alteration- but it can also be a
consequence of other (alteration) processes.
Invasional Meltdown
Invasion and Resource Supply:
- Invasion has been conceptually linked to the idea of excess available
resources. Where do these resources come from? Either some of the
native species that normally absorb resources are lost from the system,
or resources are being added to the system artificially raising the
resource level above that which would naturally be there, or both.
The Ecological History of American
Chestnut (Castanea dentata)

Castanea dentata, initial invasion (?)
Davis, M. 1969. Ecology 50:409-422

Castanea dentata, initial invasion (?)
Paillet, F. L. 2002

Castanea dentata, initial invasion (?)
Delcourt et al. 1998


C. dentata, maximum extent
By 1900: chestnut was
found throughout most of
the Eastern Deciduous
Forest.

( ~ 200 million acres)

Russell (1987)


C. dentata, extent
Chestnut distribution at the county level (early 1900s)

Transeau (1935)

C. dentata, abundance/dominance
Chestnut reached enormous size
(13 feet DBH..heights of 120 ft. [Brewer 1995])
…and formed pure stands
(> 80 % Basal Area in some stands)

Chestnut grew extremely fast…even in a forested setting.
Q. velutina
C. dentata
10
8
6
4
2
2001
1999
1997
1995
1993
1991
1989
1987
1985
1983
1981
1979
1977
1975
1973
0
1971

C. dentata, extent
McEwan and McCarthy (unpublished)
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C. dentata, ecological importance
Soil effects?

Coarse Woody Debris

Paillet 2002
Boetcher and Kalisz (1990)

C. dentata, ecological (and practical) utility
The most decay resistant
wood of any eastern tree
(Brewer 1995).
Heavy and reliable seed
crop (Brewer 1995)
The Chestnut Blight
In 1904, it was noticed that
chestnuts in New York city were
exhibiting a strange canker
This canker was caused by the fungal
pathogen Endothia parasitica…
Changed to: Cryphonectria parasitica.
The Chestnut Blight
Biology of C. parasitica
- Asian in origin
- Member of the Ascomycota
Reproduces sexually and asexually…both
routes produce wind/rain splash dispersed
spores (conidia and ascospores, respectively)
Photos from: http://botit.botany.wisc.edu/toms_fungi/may98.html
The Chestnut Blight
Disease Progression
--
Trees are infected via fissures in the bark (or lenticels).
-- Cankers form.
-- Cankers girdle tree…tree dies (rapidly).
-- 100% mortality in (practically) every stand.
Photos from: The Canadian Chestnut Council: http://www.uoguelph.ca/~chestnut
The Chestnut Blight
The disease migrated along
the Appalachian Mountains
very quickly (25 miles/
year).
By 1960, chestnut blight had
spread throughout the native
range of C. dentata.

The Chestnut Blight
This migration route is not unique…
The Chestnut Blight
- Contrary to popular belief, Cryphonectria parasitica,
is NOT host specific.
--
Impacts many species in the Family (Fagaceae).
--
Does not (generally) cause mortality.
--
In eastern forests, C. parasitica, is particularly
common on scarlet oak (Quercus coccinea: look for
orange pustules) .
--
Provides a ready source of inoculum.
The Chestnut Blight
Chestnut remains important as an
understory sprout.

From Paillet (2002)
The Chestnut Blight
Castanea dentata was rendered
functionally extinct as a canopy tree
throughout its native range..in a matter
of decades.
Chestnut Restoration: Hypovirulence
In 1951, a “strain” of C. parasitica was
discovered that was less damaging.
Dubbed “Hypovirulence”, this aided in
chestnut restoration in Italy
Caused by a viral disease (or suite of
diseases) of the Cryphonectria fungus!!
After initial promise, has failed to have
stand-level impacts in N.A.
Anagnostakis, S. L. (1982)
Chestnut Restoration: Breeding Program
The American Chestnut Foundation has
developed a program to breed blight
resistant American chestnuts.
American chestnut crossed with Asian
chestnuts (Castanea mollissima or C.
crenata).
Hybrid then back-crossed with American
Trees that are 94% American now available.
Near 100% Americans available by 2006
American Chestnut Foundation:
http://www.acf.org/
Chestnut Restoration: challenges
The chestnut blight left us with an information vacuum…
how to proceed?
Regeneration niche ?
- shade tolerance
- silvicultural considerations
Fire ecology ?
- Thin bark
- Coincidence with charcoal
Delcourt et al. 1998.
Photo by Corie McCament, Ohio University
John Pickering, University of Georgia, Athens.
Chestnut Restoration: challenges
Future challenges: Lymantria dispar
Rieske et al. 2003
Chestnut Restoration: challenges
Future challenges: Phytothora cinnamomi
Russell (1987) and others indicate that
Phytopthora was a problem prior to the
arrival of Cryphonectria.
Brosi (2001) found 60% chestnut
mortality within 4 months of planting.
J. Watkins, U. of Nebraska
Rhoades et al. 2003
Summary
?
The loss of American chestnut, although in
itself is an interesting ecological story. It is
perhaps most interesting as a cautionary taleor maybe even predictive- of an invasive
species onslaught in eastern forests.
Restoration in forests of eastern North
America (all of North America for that matter)
may ultimately be an exercise in reintroducing
decimated species. For example:
Fungi
-Dogwood anthracnose
-Dutch Elm Disease
-Butternut Canker
-White pine blister rust
Insects
-Hemlock adelgid
-Emerald Ash Borer
-Gypsy Moth (generalist)