Tree species diversity promotes litterfall productivity through crown complementarity in subtropical forests

1. The role of niche complementarity for driving the positive biodiversity-ecosystem productivity relationship has been widely recognized, but there is scant evidence regarding the role of tree canopy structure on this relationship. Litterfall productivity is proportional to forest net primary productivity in natural forests, and we hypothesized that litterfall productivity would increase with tree species diversity via increased tree crown complementarity.
2. We investigated annual litterfall productivity, species diversity, tree crown architecture, soil moisture content, soil carbon content, and stand age across 28 subtropical forest plots in eastern Zhejiang province, China. Simple linear regression was used to examine bivariate relationships among rarified species richness, crown complementarity, total crown volume, soil moisture content, soil carbon content, stand age, and litterfall productivity. Structural equation modeling was employed to quantify the direct and indirect effect...