Abstract
The tree and shrub species on a 16-ha watershed in the Coweeta Basin were sampled in 1984 and again in 1991 to determine the effects of drought on tree species composition and basal area growth. Mortality and radial growth were determined for tree species within three community types that represent a moisture gradient from moist to dry: covhardwoods > mixed-oak > oak-pine. Tree mortality from 1984 to 1991 was 20% and 23% of the cove-hardwoods and mixed-oak communities, respectively, compared to only 12% in the oak-pine type. With the exception of
Oxydendrum arboreum and
Robinia pseudoacacia, the oaks had higher percentage mortality than any other genus:
Quercus velutina had 29%, 37% and 20% mortality in the cove-hardwoods, mixed-oak, and oak-pine types, respectively:
Quercusprinus had 23% mortality in the mixed-oak type;
Quercus coccinea had 36% mortality in the mixed-oak type; and
Quercus marilandica had 27% mortality in the oak-pine type. Mortality occurred mostly in the small-size class individuals (< 10 cm in diameter) for all species, suggesting that thinning was still an important process contributing to mortality 29 yr after clearcutting. Although growth of
Liriodendron tilipifera was much higher than growth of either
Quercus prinus or
Quercus coccinea, growth in
Liriodendron was significantly reduced by the 1985-88 drought and no growth reduction was observed for these two dominant
Quercus species during thr same time period.
Keywords
Coweeta Basin,
Disturbance, Forest dynamics, Loriodendron tulipifera, Quercus, Southern Appalachians
Citation
Elliott, Katherine J.; Swank, Wayne T. 1994. Impacts of drought on tree mortality and growth in a mixed hardwood forest. Journal of Vegetation Science 5: 229-235
