Microarthropods influence rates of soil organic matter decomposition and nutrient release in forest ecosystems. Their most important effects are assumed to occur through interactions with the microflora. Although microarthropods generally increase decomposition rates of litter, their effects on nutrient fluxes in the forest floor have not been well documented. This is especially true for nitrogen, which is often immobilized in decaying litter during the initial stages of decomposition. This one-year project will test and develop the methods for the long range study and will focus on: 1) identifying and quantifying potential non-target effects of naphthalene using both field and laboratory approaches, 2) completing a one-year field study of the effects of microarthropod exclusion on litter decomposition rates, the microbial decomposer community, and nitrogen dynamics in litter and soil pools, and 3) using 15N in conjunction with the litterbasket technique to quantify the effects of microarthropod exclusion on immobilization and movement through the forest floor profile of exogenous sources of nitrogen. Experiments will also be completed on the 15N labeling of litter for use in long-term studies of decomposition and nitrogen mineralization. //