关键词: 群落相似度, 零模型, 大样地, 群落构建, 生境异质性, 空间隔离, t检验

Abstract: [Objective] Studying the relative effects of local ecological processes on community similarity is important for explaining and predicting the responses of vegetation to disturbances, as well as for understanding the dynamics of community diversity, which provides supports for species coexistence mechanisms and biodiversity conservation.[Method] We used the data of three large permanent sample plots, where all trees with a diameters at breast height (DBH) ≥ 1 cm were identified, measured and georeferenced, and we divided the community into different habitat types according to topographical factors. By using null models, we established randomized-among-habitat communities and randomized-within-habitat communities. We calculated the community similarity of observed and randomized communities and compared the differences between the two types of communities to reveal the effects of habitat heterogeneity and spatial segregation on community structure. Specifically, we tested four hypotheses. 1) Whether the community similarity significantly differed between observed and randomized-among-habitat communities? 2) Whether the community similarity significantly differed between the two types of communities? 3) Whether the community similarity significantly differed between the two types of communities? 4) The difference of community similarity between the two types of communities represents the effects of habitat heterogeneity, and the difference of community similarity between the two types of communities represents the effects of spatial segregation within habitat, are they significantly different from each other?[Result] The difference of community similarities between the observed and randomized-among-habitat communities was significant, indicating that the community assembly was obviously affected by the combined effects of habitat heterogeneity among habitats and spatial segregation within habitats. The difference of community similarity between the observed and randomized-within-habitat communities was significant, indicating that spatial segregation within habitats had a remarkable influence on community assembly. The difference of community similarity between the randomized-within-habitat and randomized-among-habitat communities was significant, indicating that habitat heterogeneity separately had notable effects on community assembly.The difference of community similarity between randomized-among-habitat and randomized-within-habitat communities (P_wh+ah-P_wh) was significantly lower than that of community similarity between randomized-within-habitat-and observed communities (P_wh-P_ob), indicating that the effects of within-habitat spatial segregation had a stronger influence on community assembly than habitat heterogeneity.[Conclusion] We conclude that in the process of community assembly of the broad-leaved Korean pine forest in Jiaohe temperate forests, the community structure was affected by both habitat heterogeneity and within-habitat spatial segregation, besides, the effects of spatial segregationon community assembly was greater than that of habitat heterogeneity. This study is important for the biodiversity conservation of temperate forests in Northeastern China, broad-scale process should be considered for further studies in the future.

Key words: community similarity, null model, permanent sample plot, community assembly, habitat heterogeneity, spatial segregation, t test