Plant diversity accumulators govern local spatial diversity

The formation and maintaining mechanism of biodiversity is the core issue in ecology. The relative importance of deterministic process based on ecological niche theory and stochastic process based on neutral theory to structuring spatial diversity pattern was studied in a temperate forest community, the spatial scales at which both processes worked were quantified. On the basis of mapped trees in a 520 m x 420 m plot of half-mature forest, individual species-area relationship was used to quantify the effect of specific species on the local species diversity. Both homogeneous Poisson process and heterogeneous Poisson process were used to test the significance of target species biased from neutrals. The results showed that most of tree species were diversity accumulators at small spatial scales except Pinus koraiensis, Larix olgensis and Populus cathayana. Diversity accumulators and diversity neutrals together structured the spatial diversity. The relative importance of both diversity accumulator and diversity neutral was closely related with spatial scale. The proportion of diversity accumulators decreased with the increase of spatial scale. On the contrary, that of diversity neutrals increased with the increase of spatial scales. Diversity repellers kept in a low proportion and had little changes. Diversity accumulators dominated at small and medium spatial scales in the community, while diversity neutrals dominated at large spatial scales. Thus, deterministic process and stochastic process were coupled and structured the pattern of local spatial diversity together in the studied temperate half-mature forest.