Watershed liming and pit and mound topography effects on seed banks in the Adirondacks, New York, USA

Abstract

Seed bank species composition, density, and frequency were evaluated as seedling emergence relative to differences in substrate chemistry associated with watershed liming and pit and mound topography (microsites) on the Woods Lake watershed, western Adirondack Mountains, NY. Liming was expected to affect calcicole and calcifuge species richness and density, while species that form persistent versus transient seed banks were expected to vary with microsite. Two of five subcatchments were limed in October, 1989 with 6.89 t ha −1 of pelletized CaCO 3. Forest floor samples were collected in May 1991 and 1992 from pit, mound, and undisturbed microsites in limed and reference (untreated) subcatchments. Water soluble calcium concentrations in forest floor samples collected in May 1992 from limed subcatchments were almost ten times greater than forest floor samples from reference subcatchments, but there were no differences in soluble calcium concentration among microsites within a subcatchment. Species richness and abundance varied among microsites, but the magnitude depended on year and lime treatment. Relative frequencies of Betula alleghaniensis (yellow birch) and Oxalis acetosella (wood sorrel) exceeded 80% in both years, with a slightly greater frequency from limed than reference subcatchments. Differences in relative frequency for several species between subcatchments were not consistent between years. The relative frequency of all species by microsite was generally greater from limed than reference subcatchments. Total density and the density of individual species by microsite varied between treatments within subcatchments and between years, although some patterns exist. Seed bank patterns vary appreciably between years and among microsites. Differences in seedling emergence from pit versus mound microsites varied between years and depended on whether the microsites were in limed or reference subcatchments. These data suggest that there are no detrimental short-term effects of watershed liming on seed banks of upland deciduous forests. Microsites may affect plant community composition most through germination and survical of propagules.