Drought Impacts on Tree Growth and Mortality of Southern Appalachian Forests

Brian D. Kloeppel Barton D. Clinton James M. Vose Aaron R. Cooper

The Coweeta LTER Program represents the eastern deciduous forests of the southern Appalachian Mountains in the United States. Coweeta Hydrologic Laboratory was established in 1934 and hence has a long record of climate measurement and vegetation response to both natural and human disturbance (Swank and Crossley 1988). The general climate of the area is classified as marine humid temperate because of high moisture and mild temperatures (Critchfield 1966; Swift et al. 1988). These conditions have favored the evolution of high species diversity in organisms in the southern Appalachians at many levels.

In recent years, however, Coweeta has experienced several droughts that have caused significant tree growth reduction and increased mortality rates (Swift et al. 1990; Clinton et al. 1993; Vose and Swank 1994; McNulty and Swank 1995). In this chapter, we describe the general climate and features of Coweeta as well as the impact of droughts on tree growth and mortality. The timescale of this climate variability is annual, with the potential for preexisting soil moisture conditions either providing a buffer or further exacerbating the drought conditions.

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