Decomposability of leaf and wood litter are not correlated across species: effects of litter traits on decomposition in field and laboratory conditions

Abstract

Changes in tree species composition have important effects on the overall rate of litter decomposition at a community level because litter decomposability varies among species and between leaf and wood litter. To understand how changes in tree species composition affect litter dynamics and carbon sequestration at the ecosystem level, it is important to clarify interspecific variations in leaf and wood litter decomposability, and the traits driving the variation. Using field data, field experiments, and laboratory experiments, we explored rates of leaf and wood litter decomposition and their relationships to traits of ten deciduous hardwood species in a temperate forest in Japan. Rates of leaf and wood litter decomposition at the community level were also estimated by considering species‐specific litter inputs and decomposition rates. Rates of leaf and wood litter decomposition were not correlated under either field or controlled laboratory conditions. This is probably because the traits that affect decomposition rate differ between leaf and wood litter. Interspecific variation in litter decomposability of leaves and wood was generally consistent between field conditions and laboratory experiments using a single fungus, suggesting that the decomposing fungi set the species‐specific decomposition rates. Moreover, the leaf and wood traits that affected decomposition by their specific fungi were different. The aboveground input of wood litter was less than half that of leaf litter, but its half‐life was > 3 times longer, suggesting that wood and leaves make similar contributions to litter accumulation. Focusing on either leaf or wood litter alone may produce misleading estimates of how species composition changes affect litter dynamics at the community level. Our results provide insight into predicting the response of carbon dynamics to future climate change.