Diversity begets stability: sublinear growth and competitive coexistence across ecosystems*

The unfolding global biodiversity crisis brings special urgency to understanding how diverse ecosystems are naturally stabilized. Whereas conventional wisdom and empirical observation suggest that stability increases with diversity, ecological theory has long made the opposite prediction, leading to the longstanding "diversity-stability debate". Here we show this puzzle is resolved through a model where growth scales as a sublinear power law with biomass (exponent < 1), exhibiting a form of population self-regulation analogous to models of individual ontogeny. We show that competitive interactions in a community with sublinear growth do not lead to exclusion, but instead promote stability at higher diversity. Our model realigns theory with classic observations and large-scale macroecological patterns. However, it makes an unsettling prediction: biodiversity loss may accelerate the destabilization of ecosystems.