EFFECTS OF LONG-TERM DROUGHT ON THE HYDROLOGY AND GROWTH OF A WHITE-PINE PLANTATION IN THE SOUTHERN APPALACHIANS

The southern Appalachians experienced record precipitation deficits for 4 consecutive years in the mid-1980s. We analyzed the impacts of the drought on the hydrology and stemwood growth of a 33-year-old white pine plantation. Increment cores and dendrometer bands indicated a significant reduction in basal area growth during the drought for all tree classes (dominant, codominant, and intermediate) and shifts in patterns of seasonal growth. There was little variation in pine foliage litterfall over the drought period, but substantial variation in other litter-fall components (e.g. wood, cones, seeds, etc.). Precipitation-runoff (P-RO) relationships indicated less variation in evapotranspiration (ET) over the drought period than predicted by simulation modeling. The discrepancy between measured and modeled ET may be related to the importance of stored soil water to streamflow which dampens P-RO ET estimates. Regression analyses showed that growing season water potential explained as much as 61% of the variation in annual basal area growth. No significant relationships were established with climatic variables alone.