短花针茅荒漠草原斑块尺度物种多样性及其共存格局

阐明斑块尺度上物种共存格局，对于深入认识荒漠草原破碎化草地生物多样性的维持机理具有重要意义。按斑块的土壤生境退化程度，选取短花针茅荒漠草原3类典型群落斑块为研究对象，对比分析不同斑块的物种构成、多样性及物种间的共存关系格局。结果表明：① 斑块A属单优种短花针茅（Stipa breviflora）群落；斑块B为短花针茅+草木樨状黄耆（Astragalus melilotoides）群落；斑块C为苦豆子（Sophora alopecuroides）+老瓜头（Cynanchum komarovii）+猪毛蒿（Artemisia scoparia）群落。② 群落结构中斑块A和斑块B多样性相近，均高于无短花针茅生长的斑块C。③ 基于零模型的分析结果显示，物种共存格局的复杂性和强度为：斑块A>斑块B>斑块C，且下降趋势明显，斑块A存在的16组显著物种对中有4组为显著竞争关系，而斑块C中的物种对减少到7组，且仅存在猪毛蒿与苦豆子组显著竞争物种对。结论：表明未沙化的土壤生境斑块是荒漠草原破碎化草地生物多样性维持的一个重要前提，土壤生境的退化显著降低了斑块内部群落组织的复杂性和物种间相互作用的强度，不利于群落的自我维持。

Species Diversity and Co-Occurrence Pattern at Patch Scale in Stipa breviflora Desert Steppe

Clarifying the species co-occurrence pattern at patch scale is of important significance for understanding the maintenance mechanism of biodiversity in desert steppe fragmentation. According to the degree of soil habitat degradation at patch scale, this study contrasted and examined the species composition and diversity of different patches and the species co-occurrence pattern based on three typical patches in a Stipa breviflora desert steppe. The results indicated that① Patch A was aconsociation and belonged to a community of S. breviflora. Patch B was a community of S. breviflora and Astragalus melilotoides. And Patch C was a community of Sophora alopecuroides + Cynanchum komarovii + Artemisia scoparia). ② In community structure, the diversity of Patch A and Patch B was similar and higher than that of Patch C where S. breviflora grew. ③ The analyzed results based on the null model showed that the complexity and intensity of species co-occurrence patterns was in an order of Patch A > Patch B > Patch C. Four of the 16 significant species pairs in patch A had a significant competitive relation, while the species pairs in patch C were reduced to 7 groups, and there was only one significant competitive species pair (A. scoparia and S. alopecuroides) in patch C. Therefore, Non-desertified soil habitat patches were the important prerequisite for the biodiversity maintenance of desert steppe fragmentation. The non-desertified of soil habitat reduced significantly the complexity of community structure within patches and the intensity of interaction between species, which was unconducive to the self-maintenance of the community.