Cornus florida L. mortality and understory composition changes in western Great Smoky Mountains National Park.

JENKINS, M. A. (Twin Creeks Natural Resources Center, Great Smoky Mountains National Park, Gatlinburg, TN 37738) AND P S. WHITE (Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599). Cornus florida mortality and understory composition changes in western Great Smoky Mountains National Park. J. Torrey Bot. Soc. 129: 194-206. 2002.-Remeasurement of woody vegetation on permanent plots in western Great Smoky Mountains National Park indicated that understory composition and dominance have changed over the past two decades (between 1977-1979 and 1995-2000). We observed heavy mortality of Cornus florida L., likely as a result of infection by Discula destructiva Redlin, a destructive fungus that causes dogwood anthracnose. Mortality was highest in smaller size classes and seedling density generally decreased. Cove and alluvial forests, where heavy shading favors dogwood anthracnose, had the highest mortality. While still high, mortality in oak-hickory and oak-pine forests was lower than that of cove and alluvial forests. Cornus florida density more than doubled on three plots located within an area that burned in 1976, likely as a result of sprouting and reduced shading in these fire-thinned stands. Over the same two decades, the importance of Tsuga canadensis (L.) Carr. greatly increased in cove, alluvial, oak-hickory, and oak-pine stands. Changes in understory composition in conjunction with the widespread loss of C. florida may greatly impact numerous ecological relationships in these forests, including calcium availability, nutrient cycling, and food source availability for wildlife.