Conclusion
Information on how species diversity influences biomass production are vital to support forest management and preserve biodiversity. In this study, we examined the relationships between AGB and multiple diversity metrics in mixed species stands. We found that (i) AGB was positively influenced by species richness; (ii) most important predictors of AGB were functional evenness and structural diversity; (iii) functional evenness and structural diversity mediate aboveground biomass positive response to species richness. Our research therefore underlines the importance of tree species richness as a primary driver of aboveground biomass. Functionally or morphologically different species have different specialized strategies to optimize resources uptake and use. Altogether, our results suggest that resource-use complementarity, the ability of different species with functional and structural (tree size and crown) differentiation to efficiently use the limited resources, is the main mechanism governing positive diversity-biomass relationship in mixed species stands. The study further suggests that maintaining high structural diversity and functional diversity would contribute to preserve biodiversity and enhance biomass stock.