Comparison of field and laboratory microcosm methods on the mass loss ofQuercus serrata andPinus densiflora leaf litter

The decay rates of Japanese Konara Oak (Quercus serrata Murray) and Japanese Red Pine (Pinus densiflora Sieb. et Zucc.) leaf litter were monitored for one year. It aimed to compare the decomposition of leaf litter using microcosms set up in the field (FM) and in the greenhouse (GM), with the litterbag (LB) method as control. Results showed that incubation setting affected the decay rate (k), respiration rates and the changes in the concentrations of nitrogen (N). Thek value ofQuercus in FM was higher than LB, while thek value ofPinus was higher in the LB than in FM. The decay ratesk for both species, however, were significantly lower in GM than FM and LB, clearly suggesting that decay rate was inhibited in the greenhouse. Significant differences in microclimatic variables and soil biological activities (soil respiration) existed between greenhouse and field microcosms, hence, the decay rates were affected. The N concentrations for both litter types increased as decomposition proceeded. Decomposition studies using laboratory microcosm approach alone may lead to erroneous conclusions especially if no appropriate field studies are conducted along with it. Part of this paper was presented at the XXth International Union of Forestry Research Organization (IUFRO) World Congress, August 6–12, 1995, Tampere, Finland.