INFLUENCE OF FOREST FLOOR TYPE ON RATES OF LITTER DECOMPOSITION IN MICROCOSMS

Rates of mass loss of leaf litter of paper birch were measured during a 70 wk laboratory incubation in microcosms containing forest floor ma terial from red alder (C-to-N ratio = 27), Douglas fir (C-to-N, 32), a nd lodgepole pine (C-to-N, 59) forests. Massless from leaf litter was fastest in alder forest floors and slowest in pine, and so was related to the C-to-N ratio of the forest floors. The decomposition rate was related to the amount of KCl-extractable N-4(+)-N and NO3--N in each m icrocosm: but not to the concentrations of extractable N (mg g(-1)), w hich were greater in Douglas fir forest floors than in alder for most of the incubation. There were larger amounts of faecal material from s oil fauna in the litter incubated in the alder forest floors, indicati ng greater faunal activity in these floors. The relationship between r ates of decomposition and N concentrations may be due to the influence of soil fauna activity on both factors, rather than to a direct influ ence of N availability on rates of litter decomposition. Copyright (C) 1996 Elsevier Science Ltd