Frequent coexistence of closely related tree species on a small scale in temperate evergreen forests in Japan

Abstract

Understanding how biotic interaction affects species composition and distribution is a major challenge in community ecology. In plants, negative reproductive interaction among closely related species (i.e., reproductive interference) is known to hamper the coexistence of congenic species. Since the magnitude of reproductive interference in plants depends on pollen flow distance, we hypothesized that the coexistence of congeners on a small spatial scale would be less likely to occur by chance but that such coexistence would be likely to occur on a scale larger than pollen flow distance. In the present study, we tested this hypothesis using spatially explicit woody plant survey data. Contrary to our prediction, congenic tree species often coexisted at the finest spatial scale and significant exclusive distribution was not detected. Our results suggest that cooccurrence of congenic tree species is not structured by reproductive interference, and they indicate the need for further research to explore the factors that mitigate the effects of reproductive interference.