Ecological Restoration (BIO 409) Dr. McEwan Invasion Ecology.
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Transcript of Ecological Restoration (BIO 409) Dr. McEwan Invasion Ecology.
Ecological Restoration (BIO 409)Dr. McEwan
Invasion Ecology
Regional Invasive Species Pool
Dis
pe
rsal
Colonization
# 1{
# 2
Proliferation Proliferation
# 3habitat space
Regional Invasive Species Pool
Dis
pe
rsal
Colonization
# 1{
# 2
Proliferation Proliferation
# 3habitat space
The invasion process involves three general phases…
Colonization
Prol
ifera
tion
{ Lag
Pha
se {Lo
g Ph
ase
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 The Ecological History of American Chestnut (Chestnut (Castanea dentataCastanea dentata))
Davis, M. 1969. Ecology 50:409-422
Castanea dentata, initial invasion (?)
Paillet, F. L. 2002
Castanea dentata, initial invasion (?)
Delcourt et al. 1998
Castanea dentata, initial invasion (?)
By 1900: chestnut was found throughout most of the Eastern Deciduous Forest.
Russell (1987)
C. dentata, maximum extent
( ~ 200 million acres)
Chestnut distribution at the county level (early 1900s)
Transeau (1935)
C. dentata, extent
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.
C. dentata, extent
McEwan and McCarthy (unpublished)
C. dentata, ecological importance
Soil effects?
Coarse Woody Debris Paillet 2002
Boetcher and Kalisz (1990)
The most decay resistant wood of any eastern tree (Brewer 1995).
C. dentata, ecological (and practical) utility
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
Photos from: http://botit.botany.wisc.edu/toms_fungi/may98.html
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)
The Chestnut Blight
Photos from: The Canadian Chestnut Council: http://www.uoguelph.ca/~chestnut
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.
The disease migrated along the Appalachian Mountains very quickly (25 miles/ year).
The Chestnut Blight
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.
In 1951, a “strain” of C. parasitica was discovered that was less damaging.
Chestnut Restoration: Hypovirulence
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)
The American Chestnut Foundation has developed a program to breed blight resistant American chestnuts.
Chestnut Restoration: Breeding Program
American chestnut crossed with Asian chestnuts (Castanea mollissima or C. crenata).
Hybrid then back-crossed with American
Trees that are 94% American now available.
American Chestnut Foundation: http://www.acf.org/
Near 100% Americans available by 2006
Regeneration niche ?
- shade tolerance
- silvicultural considerations
Chestnut Restoration: challenges
Fire ecology ?
- Thin bark
- Coincidence with charcoal
The chestnut blight left us with an information vacuum…
how to proceed?
Photo by Corie McCament, Ohio University
John Pickering, University of Georgia, Athens.Delcourt et al. 1998.
Chestnut Restoration: challenges
Rieske et al. 2003
Future challenges: Lymantria dispar
Chestnut Restoration: challenges
Rhoades et al. 2003
Future challenges: Phytothora cinnamomi
Brosi (2001) found 60% chestnut mortality within 4 months of planting.
Russell (1987) and others indicate that Phytopthora was a problem prior to the arrival of Cryphonectria.
J. Watkins, U. of Nebraska
Summary
?
The loss of American chestnut, although in itself is an interesting ecological story. It is perhaps most interesting as a cautionary tale- or 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)