EFFECT OF TEMPERATURE ON DECOMPOSITION AND DEVELOPMENT OF MICROFUNGAL COMMUNITIES IN LEAF LITTER MICROCOSMS

The influence of temperature on litter decomposition rates and on the composition and structure of microfungal communities was determined by incubating milled, deciduous leaf litter in microcosms at 0, 10, and 20-degrees-C. Changes in species composition were assessed after 10 and 90 weeks using the dilution-plating method. Dry weight loss from litter after 90 weeks was 13.5, 19.0, and 30.7% at 0, 10, and 20-degrees-C, respectively. Temperature caused major differences in the species composition and structure of the microfungal communities isolated. As temperature decreased, Zygomycete species richness increased, whereas Deuteromycete species richness decreased. Although species richness was similar at all three temperatures, diversity was highest at 20-degrees-C and lower at 0 and 10-degrees-C where the communities were dominated by single species. At 0 and 10-degrees-C, communities were dominated by the Deuteromycetes Geomyces pannorus and Geomyces asperulatus, respectively, and by several species in the Zygomycete genera Mortierella and Mucor. At 20-degrees-C the community consisted almost entirely of Deuteromycetes, with the genera Trichoderma, Humicola, and Sporothrix being most abundant. This study demonstrates that a distinct, low-temperature community of microfungi exists and can be active in litter at 0-degrees-C.