Evenness mediates the global relationship between forest productivity and richness

Abstract 1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels richness. However, alone cannot reflect all properties a community, including community evenness, which may mediate the between biodiversity and If evenness correlates negatively forests globally, then greater number not always overall diversity productivity system. Theoretical work local empirical studies have shown that effect on functioning be especially strong levels, yet consistency remains untested global scale. 2. Here, we used dataset from globe, includes composition, biomass accumulation net primary productivity, to explore whether way appears buffer Specifically, evaluated low speciose communities correlate attenuation richness–productivity relationship. 3. We found tree are correlated highly comprising few dominant many rare species. Furthermore, correlation changes evenness: richness, uneven more productive, while even productive. 4. Synthesis . Collectively, these results demonstrate integral attenuating forest might partly explained by communities. Productivity generally increases until reduced limits diversity. Our research suggests fundamental biodiversity–ecosystem function relationships, critical importance for guiding conservation sustainable management decisions.