The Joint Influences of Climate, Litter Quality, and Soil Fauna in Regulating above- and Belowground Decomposition: a Pan-Tropical Study

I report on the results of a collaborative study investigating the joint influences of climate, litter quality, and soil fauna in regulating above- and belowground decomposition in tropical forest ecosystems. We have assembled a network of 15 collaborators working in 22 tropical forests including sites in Hawaii, Central America, South America, India, Madagascar and Papua New Guinea. In general, most lowland tropical forests experience continually warm climates but vary greatly in the amount and seasonal distribution of precipitation. We predicted that tropical dry and wet forests differ in the degree to which decomposition processes are controlled by soil fauna and litter quality. We developed a standardized litter bag protocol that is being implemented by each collaborator at his or her field site. Preliminary results suggest that litter quality, soil fauna, and decomposition environment (above- or belowground) all influence decomposition rates among our sites, which span an order of magnitude gradient in mean annual precipitation. However, which factors are most important in each forest is idiosyncratic and cannot be predicted from climate data alone. This study is the first of its kind to simultaneously evaluate both biotic and climatic controls on litter decomposition in tropical forests at the global scale.