干旱区生态环境知识资源中心

Biodiversity is a central and multifaceted concept of community ecology, but a major challenge remains in understanding the variation mechanisms of biodiversity. Two ecological phenomena are shown in beta diversity: (a) spatial species turnover in space and (b) nestedness-resultant of assemblages. Using a field experiment focusing on a desert steppe ecosystem, we show that desertification influences those two components in divergent ways depending on whether a deterministic or stochastic process is driving community composition. Desertification was a major driver of local environmental heterogeneity, which also resulted in decreased soil nutrients and led to increased turnover in a heterogeneous environment; however, spatial turnover of species decreased with desertification intensify. Desertification decreases resource availability, which causes species loss and reduced total beta diversity. Those desertification effects, therefore, had a homogenizing effect on the community. However, stochastic processes cannot be disregarded as a factor in community composition determination. Overall, these results indicated that the study of desertification effects on beta diversity would add our knowledge of the deterministic and stochastic processes that create and maintain biodiversity. This is crucial to assess the relative importance between stochastic processes and deterministic processes.