Functional dominance is a better predictor than functional diversity of above-ground biomass in seasonally dry tropical forests

Background The mass ratio hypothesis (functional dominance) and niche complementarity hypothesis (functional diversity) are two potential approaches for making the link between biodiversity and biomass. It is yet unclear how biodiversity and biomass are related in seasonally dry tropical forest (SDTF) communities where there is a seasonal water limitation. Aims The objective of this study was to quantify the effects of environmental filtering on ecosystem functioning, especially those related to biodiversity and above-ground biomass. Methods We estimated biomass and functional traits for all species in five plots at five sites in a SDTF. We related functional diversity and community-weighted trait mean (CWM) values to above-ground biomass (AGB) using linear mixed models. Results Functional diversity was not related to AGB, while CWM values of vessel density (VD) were positively and the Carlquist Vulnerability Index (CVI) was negatively related to AGB. Conclusion The CWM values of functional traits related to the trade-off between safety of water transport and the efficiency of water conductivity and conservative strategies (VD and CVI) were good predictors of AGB. The mass ratio hypothesis appears to be a better predictor of AGB than niche complementarity in our study conducted in the SDTF.