PROCEEDINGS: Index of Abstracts

GROWTH RESPONSES OF WHITE OAK AND BLACK OAK TO DROUGHT STRESS ACROSS GRADIENTS OF ACID DEPOSITION AND MICROCLIMATE

David LeBlanc-1 and Robert Haack-2

1-Dept. of Biology, Ball State University, Muncie, IN 47306. 2-USDA Forest Service, North Central Forest Experiment Station, E. Lansing, MI 48823.

Based on data from Illinois, Indiana, and Ohio following the 1988 drought, acid deposition does not increase the susceptibility of oak trees to drought stress. Measurements at six sites along a gradient from comparatively high to low levels of acid deposition refuted the hypothesis that high acid deposition rates would predispose oaks to growth decline and mortality after a severe drought. Neither patterns of growth rate nor outbreak of two-lined chestnut borer correlate with acid deposition patterns. Differences in growth and mortality between sites appear to relate to differences in the timing and duration of drought conditions.