放牧率对内蒙古典型草原物种分布空间异质性的影响

Impacts of Stocking Rate on the Spatial Patterns of Species in Temperate Typic Steppe, Inner Mongolia

本文应用统计学研究放牧率对内蒙古温带典型草原的羊草、大针茅、冷蒿和星毛委陵菜分布空间异质性的影响。结果表明：1）放牧率对典型草原物种空间分布有明显的影响。随着放牧率的增大，羊草与大针茅空间分布的随机性减小，空间自相关尺度逐渐增大。而在退化过程中入侵的冷蒿和星毛委陵菜，空间分布的随机性逐渐增大，空间自相关尺度亦呈增大趋势。在放牧率胁迫超过一定程度时，冷蒿空间分布的自相关开始下降，而星毛萎陵菜的空间分布则表现出强烈的随机性。2）格局图谱法反应出群落演替的主要矛盾，对于草原，格局图谱不受啃食和小尺度生境变化的影响，适用于不同放牧下群落之间的比较。

Geostatistics was applied to detect the impacts of stocking rate on the spatial patterns ofspecies in temperate typical steppe. The investigated species were Leymus chinensis, Stipa grandis,Artemisia frigida and Potentilla acaulis. The results demonstrated that: 1)stocking rate imposed obviousimpacts on the spatial patterns of all the selected species. L. chinensis and S. grandis which were nativespecies experienced less random spatial occurrences and larger spatial autocorrelatin scales according to theincreasing stocking rate, in contrast, A. frigida and P. acaulis which were invading species experiencedmore random spatial occurrences and smaller spatial autocorrelating scales while the grazing pressure in-creased. 2)changes in spatial patterns of species embodied the nature of succession of community and werenot sensitive to the foraging of livestock and the heterogeneity of habitat in small scale,therefor,patternspectrum which described the dynamics of spatial patterns of the interested species provided a potentialway to detect the stage of succession of the studied community.