Data from: Development stage-dependent effects of biodiversity on aboveground biomass of temperate forests

Increasing evidence shows that biodiversity-ecosystem functioning
relationships (BEFs) become stronger as forests develop, but much of the
evidence is drawn from experiments (less than 30 years). How the diversity
effects vary with the stand development stages remain largely unexplored.
Using a large temperate forest datasets with 2,392 permanent plots in
northeastern China, we examined the relationships between biodiversity
(i.e., tree species richness, functional diversity, and functional
composition) and aboveground biomass (AGB) across the different
development stages of temperate forests (covering all stages from young to
overmature forests). Specifically, the complementarity and mass-ratio
effects across the different forest development stages were evaluated to
elucidate emerging patterns that explain ecosystem functioning. We
observed positive BEFs using both species richness and functional
diversity, but these positive effects decreased with forest development.
However, the effects of community-weighted mean (CWM) on AGB showed two
peaks in young and mature stands. Interestingly, the effects of CWM on AGB
became larger than effects of functional diversity after the forests
developed to near-mature/mature stands, indicating that BEFs are driven by
mass-ratio effects (i.e., dominant species) rather than niche
complementarity in old stands. The high AGB in young stands was
charactered by tree species with high resource acquisition ability,
however, in old stands, it was associated with tree species with both high
resource acquisition ability and conservative traits. Our findings
indicate how the developmental stage influences the effects of
biodiversity on ecosystem functioning in natural forests. The findings
tentatively advocate for a mechanistic framework of BEFs covering all
developmental stages of temperate forests, which could facilitate
formulation of effective strategies for enhancing ecosystem functioning at
different development stages.