Controls over leaf litter decomposition in a mixed evergreen and deciduous broad-leaved forest, Central China

Abstract

Our understanding of the determinants of leaf litter decomposition is lacking for mixed evergreen and deciduous broad-leaved forests compared with tropical and temperate forests. This study aimed to assess the relative importance of litter properties, climate and soil on decomposition in a mixed above-mentioned forest in a transitional zone, central China. We utilized leaf litter from seven canopy tree species in conjunction with a transplant litterbag experiment along an elevational gradient over three years by measuring decomposition rate. Initial leaf litter nitrogen (N), phosphorus (P) and magnesium (Mg) as well as C:P were robust predictors of leaf litter decomposition. Mg was the single best predictor of leaf litter decomposition across all species. Soil moisture and air temperature could predict leaf litter decomposition very well across the elevational gradient. The explanatory power of elevation-related variables (27.75 %) was much lower than that of species-related variables (38.97 %). More nutrients such as Mg than N and P commonly used in proposed indices should be taken into account when evaluating the decomposability of leaf litter. Tree species identity is the most important determinant of leaf litter decomposition in this target transitional mixed forest. Therefore, shifts in tree species composition may influence leaf litter decomposition rates more than changes in site conditions under the context of future climate change.