PROCEEDINGS: Index of Abstracts

EFFECTS OF ACIDIC PRECIPITATION ON LEAF DECOMPOSITION RATES, MICROBIAL BIOMASS, AND LEAF PACK MACROINVERTEBRATES IN SIX STREAMS ON THE ALLEGHENY PLATEAU OF WEST VIRGINIA

Erik S. Engstrom-1, Sean K. Meegan-1, Sue A. Perry-2, and William B. Perry-1

1-Graduate Students, and Professor, respectively, Division of Forestry, West Virginia University, Morgantown, WV 26506. 2-West Virginia Cooperative Fish and Wildlife Research Unit, Division of Forestry, West Virginia University, Morgantown, WV 26506-6125.

We studied the effects of acidification on leaf litter decomposition in six headwater streams in the Monongahela National Forest. These streams differed in underlying geology and mean baseflow pH (3.99, 4.24, 6.13, 6.47, 6.59, and 7.52). We placed 10-gram leaf packs of white oak, red maple, and yellow poplar in each stream, and retrieved them after two days, two weeks, and then at 4-week intervals from November 1993 to February 1994. Leaf packs were analyzed to determine changes through time in leaf decay rate, invertebrate composition, density, and biomass, and microbial biomass (ATP concentration). The mass loss rate coefficient, k, ranged from -0.0128 to -0.0052 for poplar, -0.0120 to -0.0047 for maple, and -0.0059 to -0.0018 for oak. The acidic streams had significantly lower decay rates. The acidic streams had higher invertebrate densities but lower biomass than the more alkaline streams. ATP concentrations were lower in the acidic streams than in the more alkaline streams. In streams that are vulnerable to acidification, pH depression may reduce energy and material availability to stream macroconsumers.