Document: BRU-3-69-33

Responses to severe wind disturbance in an old-growth floodplain forest.

ALLEN, B.P.* ¹ and R.R.SHARITZ ^1,2

Savannah River Ecology Laboratory, Aiken, SC 29803, USA ¹
University of Georgia, Athens, GA ²

Abstract:
Large river floodplain forests of the Southeast may not fit traditional models of forest succession. Infrequent severe wind disturbances and the flood regime may hinder development of a mature forest dominated by shade-tolerant trees. Differential patterns of survival, growth, and recruitment of canopy species following Hurricane Hugo's passage over the Congaree Swamp in 1989 indicate elevation and species-specific effects of the disturbance. Hurricane impacts and recovery were monitored in ten 1-ha permanent plots established in 1990 and re-sampled in 1994 and 1998. In heavily damaged bottomland hardwoods, adult mortality and recruitment of the shade-intolerant canopy dominants were greater than in areas of low damage. Changes in the size-class distribution of tree species indicate that forest composition is not stable through time. The canopy species of this floodplain forest are primarily shade-intolerant and are recruited only in heavily damaged areas. Models of succession in forests, based primarily on shade tolerance, predict a mature forest dominated by a mixture of shade-tolerant species (elm-ash-sugarberry). However, forest composition may be determined by the interaction between hydrologic regime and wind disturbance regime, which may retard succession and maintain dominance of shade-intolerant trees.

Keywords: Hurricane Hugo, forest dynamics, floodplain forest, old-growth

This abstract is being presented at: 10:30 AM in session:
Poster Session #12: Disturbance Ecology.