Data from: 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 effects of species richness on litterfall productivity through
tree crown complementarity. 3. Litterfall productivity increased with
rarefied species richness via increasing crown complementarity rather than
total crown volume. Species richness, crown complementarity, and
litterfall productivity increased with soil moisture content, while crown
complementarity and litterfall productivity increased with soil carbon
content. Neither species richness nor crown complementarity increased with
stand age, even though litterfall productivity increased with stand age.
4. Synthesis. Our study provides evidence for a strong role of tree crown
assembly in shaping ecosystem function in complex natural forests. Our
findings suggest that crown spatial complementarity among trees operates
mechanistically to drive the positive tree species diversity-litterfall
productivity relationship in subtropical forests. We argue that community
and/or ecosystem ecology would benefit from more attention to crown
variability among coexisting tree species.