Decomposition is a key process for nutrient cycling, plant production, and accumulation of soil organic matter in terrestrial ecosystems. Although decomposition affects ecosystem carbon and nitrogen dynamics both directly via the release of CO2, and indirectly to changes in nutrient availability or NPP, the interplay between its different compartments (biomass, leaching and CO2) remain poorly understood. The role of interactions between plant-decomposers influencing decomposition rates is less known. We thus assessed the effects of plant-fungal interactions on decomposition rates by measuring mass loss, CO2 evolution, and nutrient leaching in microcosms. We also determined the initial and final chemistry of the leaves, and estimated the final fungal biomass. Each microcosm contained a single plant-fungal combination, and each plant-fungal combination was replicated three times. In general, the combinations that lost more biomass also produced more CO2. For all plant species NH4+N accounted for more than 80% of the N leaching. NO3-N, TDN, and DON contribution to N leaching was small. The initial N leaching of two legume trees was greater than that of the other tree species. The initial NH4+N leaching between the two Inga species was not significantly different, but their NH4+N leaching was significantly different from the three other species (P=0.05). After 17 weeks the contribution of Sapium laurocerasus, a non-legume species, to NH4+N leaching increased 12-fold, approaching the initial NH4+N legume leaching. All other plant NH4+N leaching drastically decreased and their means were similar. S. laurocerasus was significantly different from all the other species (P=0.05). The understanding of the contribution of the leaf litter of different tropical species to nutrient leaching can be a good tool for forestry managers while the carbon signatures CO2, biomass, and nutrients could be useful in global change research.
