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Schwager, M - American chestnut

Page history last edited by PBworks 13 years ago
American Chestnut Tree
Castanea dentata

   The American Chestnut is a hardwood tree found in the Eastern United States. I picked this plant because of my interest in plant pathology. The Chestnut’s near eradication by the Chestnut Blight made it an instant draw for me. It is actually the reason I have chosen plant biology to be my major. The thought that such a great tree was struck from its throne as king of eastern forests by such a small organism intrigues me. I’ll always remember fall quarter of 2007 when I took “Plant Pathology” and we learned about what a great thing we lost to Chestnut Blight.
    The chestnut is a woody perennial native to the Eastern United States. Its habitat, as defined by the WWF, is Temperate Broadleaf & Mixed Forests (Temperate…[Updated 2006]). Its most active growth period is during the Spring and it has its bloom period in early Summer. (USDA 2008) With a medium drought tolerance and the ability to survive to temperatures down to -33o (USDA 2008), it is no wonder this plant has such a broad range. Its fruit is “a triangular nut, [with] two to three enclosed in a large burr.” (Samuelson and Hogan 2006) It is becoming rarer because of the fungus Cryphonectria parasitica (Anagnostakis 2000) or as it is more commonly known, Chestnut Blight. The trees, which used to grow to heights of 100 feet, now rarely make it to 30 feet before the blight kills them. (Samuelson and Hogan 2006) Many states, such as Kentucky and Tennessee, have the Chestnut listed as an endangered species or a species of special concern (USDA 2008).    

    The American Chestnut tree’s “claim to fame” is its demise at the hyphae of Cryphonectria parasitica. The only saving grace for the chestnut is its ability to grow from the stump of another chestnut. “Sprouts develop from a burl-like tissue at the base of the tree called the ‘root collar,’ which contains dormant embryos.” (Anagnostakis 2000) This ability allows the chestnut to continue growing though its predecessor may not have reached fruit-bearing age. As plant pathologist Jim Worral puts it, “before they can get big enough to sexually reproduce, the damn disease cuts them down.” (Worral 2007) This disease is especially brutal because of the Chestnut’s many commercial uses. The American Chestnut’s use as lumber and a source of tannin, used to tan hides, was legendary. It also produced chestnuts, an important food source for many animals, from Turkeys to people. (Samuelson and Hogan 2006) Once more, Jim Worral puts it best with the statement “if you could custom design the ideal tree species, you couldn't come up with a better one than American chestnut.” (Worral 2007) 

    You might think that if the trees continue dying, why doesn’t the disease die as well? This is because the fungus can survive on, and sometimes infect, oak trees. This means the fungus has a ready place to stay while the chestnut saplings are growing. (Worral 2007)
    There does seem to be a glimmer of hope though. Work is currently being done on creating a hybrid of the American Chestnut, which is very susceptible to Chestnut Blight, and the Chinese Chestnut, which is resistant to the fungus. (Worral 2007) The Chinese Chestnut’s resistance is to be expected as the fungus originated in eastern Asia and was introduced into the United States. (Worral 2007) The loss of the Chestnut tree in places where “it made up about 50% of most eastern hardwood forests” (Worral 2007) was a terrible tragedy. But hopefully, through hybridization or otherwise, this majestic tree will make a comeback. Keep your fingers crossed!



Quick List:
Common Name: American Chestnut
Scientific Name: Castanea dentata
WWF Habitat: Temperate Broadleaf and Mixed Forests
Growth Form: Perennial Tree
Fruit: Triangular Nut

Major Threats: Chestnut Blight
Invasive: No
Frequency: Rare
Native Range: Eastern United States, from Maine to Mississippi



Temperate Broadleaf & Mixed Forests


    The American Chestnut tree’s biome, as defined by the WWF, is Temperate Broadleaf and Mixed Forests. This biome is found all around the world, but the American Chestnut is not found everywhere this biome is. The American Chestnut is found in the ecoregion known as “Appalachian and Mixed Mesophytic Forests” (Appalachian…[updated 2006]). An ecoregion, as defined by the WWF, is a "large unit of land or water containing a geographically distinct assemblage of species, natural communities, and environmental conditions"(Appalachian…[updated 2006]). This ecoregion is found in the eastern united states and encompasses “almost every forest type that occurs in the eastern half of North America, from mixed deciduous forests in the lowlands to spruce-fir forests, similar to boreal forests a thousand miles to the north” (Appalachian…[updated 2006]).

    Temperate Broadleaf and Mixed Forests are found all over the world, from Russia to Australia to the Eastern United States. The Broadleaf and Mixed portion of the biome’s name refers to the fact that deciduous and coniferous trees are growing side by side. The signature of temperate forests is their greatly varied rainfall which produces the mix of tree types found there and this causes a surprising amount of biodiversity to be found in temperate forests. Trees ranging from the mighty oak towering over the smaller saplings of the once great Chestnut, to the covering of needles shed from a Pine, tell a story of change. This biome consists of such a varied population of both plants and animals that it would take hundreds of pages to list them all. Temperate Broadleaf and Mixed forests are usually typified by oak, birch, beech, and maple trees (Temperate… [updated 2007]).

    Though not as threatened as many more famous biomes, such as Tropical and Subtropical Moist Broadleaf Forests, the Temperate Broadleaf and Mixed Forest is not free from danger. Deforestation is a big problem, especially in the Eastern United States where strip mining has become the norm. Much of the Appalachian and Mixed Mesophytic forest used to consist of old growth forests. This not the case as many of the trees were cut down in the early 1900’s to make way for agriculture and mining (Appalachian-Blue Ridge Forests [updated 2001]). Many acres of forests are clear cut and the soil is destroyed to find coal for fuel. Oddly enough, the item being found after the clear cutting (coal) is also causing another problem for these forests. Acid Rain is, as defined by the EPA, “a broad term referring to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids” (What is Acid Rain? [updated 2007]). And most of the excess nitric and sulfuric acids are by-products of the burning of fossil fuels, such as coal. According to the US EPA, “In the United States, roughly 2/3 of all SO2 and 1/4 of all NOx come from electric power generation that relies on burning fossil fuels, like coal” (What is Acid Rain? [updated 2007]). Acid Rain and Deforestation are just two of the many threats facing the United State’s Temperate Broadleaf and Mixed Forests, but in my opinion, the biggest threat to our temperate forests is invasive species. The chestnut tree was all but destroyed by an invasive fungus from Asia, so we can see that even the smallest of invaders can have a huge impact. Other invaders, such as Kudzu, threaten both plants and animals, and some, like multi-flora rose, threaten to wipe out their native counterparts all together. Something must be done to save our forests.

    One step that will greatly reduce the strain we put on our Temperate Forests is to stop strip mining for coal in the Appalachians. The best way to do this is to develop different sources of energy so we do not need coal and can stop mining for it. It would be even better if the alternative fuel we develop was clean burning, thereby helping reduce the acid rain that is also hurting the forests. The reduction in nitric and sulfuric acids would help reduce the acid deposition that kills fish and plants and contributes to the reduction of biodiversity in the forests. The problem with saving our forests comes from the fact that the biggest threat to the Temperate Broadleaf and Mixed forests of the U.S. will be the hardest to stop. Once an invasive species has entered the environment, it becomes nigh-impossible to reverse the effects. The obvious example of this is the Chestnut Blight, the fungus that has all but wiped out the majestic Castanea dentate, better known as the American Chestnut. Brought over from Asia over one hundred years ago, stopping its spread has proved fruitless. The solution now seems to be creating a hybrid cross between the resistant Chinese Chestnut and the not resistant American Chestnut. While current results look promising, this is not a viable solution for all invasives. In fact, many of the worst invaders are plants themselves and can therefore not be stopped through selective breeding of their targets as they have none. The “march” of the invasive species is best stopped through education and vigilance. Educating the public on what plants are safe to plant and which could possibly harm the environment should cut down on the number of “escaped” invasive plants. Vigilance on the part of government officials and everyday citizens will help us to identify the problem early and try to stop it before it gets out of hand.



Anagnostakis, Sandra L. 2000. Revitalization of the Majestic Chestnut: Chestnut Blight Disease. APSnet

        [Internet].[cited 2008 Feb 18] 4:54. Available from:http://www.apsnet.org/online/feature/chestnut/


 Appalachian-Blue Ridge forests [Internet]. [updated 2001]. WWF; [cited 2008 Mar 3]. Available from:                              http://www.worldwildlife.org/wildworld/profiles/terrestrial/na/na0403_full.html


Appalachian & Mixed Mesophytic Forests [Internet]. [updated 2006 Jul 7]. WWF; [cited 2008 Mar 3]. Available

        from: http://www.panda.org/about_wwf/where_we_work/ecoregions/appalachian_mesophytic_forests.cfm


 Native range of American chestnut. From Little, E.L., Jr., 1977, Atlas of United States trees, volume 4, Minor                  Eastern Hardwoods: U.S. Department of Agriculture Miscellaneous Publication 1342, 17 p., 230 maps.


Samuelson, Lisa J, Hogan, Michael E. 2006. Forest Trees: A Guide to the Eastern United States. Upper Saddle

         River [NJ]: Pearson Prentice Hall. p. 222-223.


Temperate Broadleaf and Mixed Forest Ecoregions [Internet]. [Updated 2006 Jul 11]. WWF ; [cited 2008 Feb 18].              Available from:                                                                                                                                                             http://www.panda.org/about_wwf/where_we_work/ecoregions/about/habitat_types/selecting_terrestrial_ecoregions/habitat04.cfm


USDA, NRCS. 2008. The PLANTS Database [Internet] (2008 Feb 18). National Plant Data Center, Baton Rouge, LA             70874-4490 USA. Available from: http://plants.usda.gov


USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern

        United States, Canada and the British Possessions. Vol. 1: 615.


What is Acid Rain? [Internet]. [updated 2007 Jun 8]. Washington [D.C.]: U.S. Environmental Protection Agency;             [cited 2008 Mar 3]. Available from: http://www.epa.gov/acidrain/what/index.html


Worral, Jim. 2007. Chestnut Blight [Internet]. [Updated 2007 May 17]. [cited 2008 Feb 18]. Available from:                     http://www.forestpathology.org/dis_chestnut.html


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