Appalachian mixed mesophytic forests

The Appalachian mixed mesophytic forests comprise an ecoregion in the Appalachian Mountains in eastern North America. They are one of the most biologically diverse temperate forest regions on earth. It has an unusually diverse tree flora, with as many as 30 tree species at a single site. The rivers of the ecoregion have the highest species richness of any freshwater ecosystem. In particular, there are a large number of endemic fish and shellfish species. The rich diversity of the area has several contributing factors. It was an unglaciated refugia for many species. It shares species with the high elevation Appalachian-Blue Ridge forests to the east, the hardwood forests to the west, and the mixed hardwood/conifer forests to the south.

Threats

This ecoregion is considered critically endangered with 95% of the habitat degraded or converted to commercial forest. Large areas have been destroyed through surface mining, including mountaintop removal. Large areas have also been logged and then converted to plantations of fast-growing tree species, such as Loblolly Pine ("Pinus taeda") which are then used to produce wood pulp. This is particularly a problem in the Cumberland Plateau of Tennessee. Major rivers in the ecoregion, such as the Tennessee River, have been dammed. This has resulted in the threatened or endangered status of some species of shellfish.

Natural areas in the ecoregion

Tennessee
* Fall Creek Falls State Park
* Savage Gulf State Natural Area [http://www.state.tn.us/environment/nh/natareas/savage/]
* Big South Fork National River & Recreation Area (Kentucky/Tennessee) [http://www.nps.gov/biso/]

Prehistoric period

During the Last Glacial Maximum about 18,000 years ago, the influence of Arctic air masses and boreal vegetation extended to about 33° N. latitude, the approximate latitude of Birmingham and Atlanta. Forests of the glacial period were dominated by various spruce species and jack pine; fir was abundant in some locations. With the exception of the absence of certain prairie elements, the understories of these forests were generally typical of modern spruce-fir forests within and near Canada. Temperate deciduous forests dominated from about 33° to 30° N. latitude, including most of the glacial Gulf Coast from about 84° W. longitude. Regional climate was similar to or slightly drier than modern conditions. Oak, hickory, chestnut, and southern pine species were abundant. Walnuts, beech, sweetgum, alder, birch, tulip tree, elms, hornbeams, tilias, and others that are generally common in modern southern deciduous forests were also common then. Grasses, sedges, and sunflowers were also common.

References and external links

* [http://www.worldwildlife.org/wildworld/profiles/terrestrial/na/na0402_full.html Ricketts, T.H., E. Dinerstein, D.M. Olson, C.J. Loucks, et al. (1999). Terrestrial Ecoregions of North America: A Conservation Assessment. World Wildlife Fund - United States and Canada. Island Press, Washington, D.C. pp. 337-340.]
* [http://www.nationalgeographic.com/wildworld/profiles/terrestrial/na/na0402.html National Geographic WildWorld ecoregion profile]
* [http://www.cas.vanderbilt.edu/bioimages/ecoregions/50402frame.htm Appalachian mixed mesophytic forests images at bioimages.vanderbilt.edu]
*

Data source for
http://www.worldwildlife.org/science/data/terreco.cfm Olson, D. M. and E. Dinerstein. The Global 200: Priority ecoregions for global conservation. (PDF file) Annals of the Missouri Botanical Garden 89:125-126] .