ABSTRACTThe fate of ascospores of an indigenous soil fungus,Coniochaeta nepalica, and a coprophilous species,Sordaria fimicola, supported on polyvinyl chloride membranes and introduced into the A horizon of a Long Island oak-birch forest was studied for up to 210 days. Ascospores of both species were rapidly lost from the filters during late fall and early winter when a similar decrease in the natural population ofC. nepalicaoccurred. Evidence is presented that grazing by soil arthropods rather than microbial lysis, depletion of endogenous reserves, dormancy loss, predation, or water transportation is responsible for the decrease in ascospore numbers on the filters and by analogy in soil.