FUNGAL FLORA AND RATE OF DECOMPOSITION OF LEAF LITTER AT LOW TEMPERATURES

Abstract

The succession of mycoflora and the rate of decomposition of a mixture of coniferous–deciduous leaves were followed in the laboratory over a 45-mo period at 10, 4, and 1 C. For a leaf litter fall of 3,000 kg/ha and decomposition period of 6 mo it was estimated that these temperatures would give a loss in leaf litter of 660, 420, and 270 kg/ha per yr, respectively. For each 1 degree C drop in temperature, the rate of decomposition decreased approximately 1.8%. The washed leaf particles that were incubated on agar plates at temperatures corresponding to those of the incubating litter showed that 50% of all isolates belonged to the genus Chrysosporium. The next most abundant genera were Mucor 22%, and Penicillium, 15%. These three genera were present at every sampling date and the frequency of Chrysosporium consistently increased as temperature decreased, whereas Mucor showed the opposite trend. Penicillium was more common at 4 than at 1 and 10 C. The remaining 9 genera were isolated with a frequency of less than 4% and in general were associated with particular stages of litter breakdown. Phialocephala, Cephalosporium, Gliocladium, Rhizoctonia, and sterile mycelia were at a higher frequency during the first 283 days of decomposition, whereas the frequency of Aureobasidium, Trichoderma, and Monocillium was greater after 283 days.