Spatiotemporal noise stabilizes diversity in strongly-interacting metacommunities

Classical ecological models predict that large, diverse communities should be unstable, presenting a central challenge to explaining the stable biodiversity seen in nature. We revisit this long-standing problem by extending the generalized Lotka-Volterra model to include both spatial dispersal and environmental fluctuations across space and time. We find that neither dispersal nor environmental noise alone can resolve the tension between diversity and stability, but that their combined effects permit arbitrarily many species to stably coexist despite strong competitive interactions. We analytically characterize the noise-induced transition to coexistence, tracing its origin to an effective nonlinear self-inhibition generated by the noise, and support our results with extensive numerical simulations. Spatiotemporal noise thus provides a novel resolution to the diversity-stability paradox and a generic mechanism by which complex communities can persist.