RELATIVE EFFECT OF LITTER AND FOREST TYPE ON RATE OF DECOMPOSITION

Rates of litter decomposition and metabolic rates of microbes were studied for 3 yr in four forest types at the E. N. Huyck Preserve on the Helderberg Plateau in eastern New York State. The four forests were floristically distinct, being dominated by beech (Fagus grandifolia), red pine (Pinus resinosa), hemlock (Tsuga canadensis) and mixed-hardwood (Acer saccharum and Quercus alba), respectively. Decomposition rates ranged from 0.12 g/yr/g for hemlock to 0.42 g/yr/g for mixed hardwood. To determine if these differences were a function of differences in litter type or the decomposer community, we performed a mixed litter bag experiment, in which each type of litter was placed in each forest type. Rate of decomposition was primarily a function of litter type although decomposer community and decomposer community/litter type interactions were also important. Metabolic rate of decomposers, as measured by their ability to convert C-14-glucose to C-14-CO2, corresponded to the rate at which they decomposed litter. Relative importance of bacteria and fungi to total metabolism also varied among forest types, with bacterial contribution ranging from a high of 42% in mixed hardwood to a low of 8% in hemlock.