为揭示春季休牧后放牧强度变化对短花针茅（Stipa breviflora）荒漠草原主要植物种群空间分布形式、生态位变化和种内个体关系的影响，引入多重分形理论进行分析。结果表明，主要植物种群短花针茅、碱韭（Allium polyrhizum）和无芒隐子草（Cleistogenes songorica）在各处理区的空间分布均存在多重分形特征（计盒维数D0>信息维数D1>关联维数D2）。短花针茅种群空间分布主要受低密度分布区影响（多重分形谱Δ f <0），碱韭受高密度分布区影响（Δ f >0），无芒隐子草空间分布的主导因素由低密度区（Δ f <0）转为高密度区（Δ f >0）。春季休牧+夏季重牧+秋季适牧（SA2）处理下的主要植物种群空间分布较春季休牧+夏季适牧+秋季重牧（SA1）处理复杂（多重分形谱宽Δα表现为SA2>SA1）。春季休牧能够使短花针茅植物种群生态位宽度、个体间竞争强度增加（分形维数均较CK增大），且增加程度SA2>SA1；SA1有利于碱韭和无芒隐子草生态位宽度、个体间竞争强度增加（分形维数D0、D2更趋近于2）。%In this paper, we introduced the multi-fractal theory in order to investigate the grazing intensity after banning grazing in spring how to influence the spatial distribution pattern, niche changes and the effects of the individual relations of plant population. The results shown that there was unique multi-fractal characteristics of spatial distribution on Stipa breviflora, Allium polyrhizum and Cleistogenes songorica in each grazing treatment (box-counting dimensionD0 > information dimensionD1 > correlation dimensionD2). PopulationStipa breviflora is mainly affected by the low density distribution (multifractal spectrumΔf < 0), while that ofAllium polyrhizum is mainly influenced by the high density area (Δf > 0), and the dominant factor in the spatial distribution of Cleistogenes songorica turned low-density area (Δf< 0) to a high-density area (Δf > 0). Banning grazing in spring + heavy grazing in summer + moderate grazing in autumn (SA2) led to a more complex spatial distribution relatively to banning grazing in spring + moderate grazing in summer + heavy grazing in autumn (SA1) (a wide multifractal spectrumΔα showed SA2 > SA1). Banning grazing in spring can made niche breadth and individuals competition intensity of populationStipa brevifloraincreased (fractal dimension increased than CK area), and increased the degree of SA2 > SA1. Moreover, increasing of SA1 is benefit to increase the niche breadth and individuals’ competition intensity of populationAllium polyrhizumandCleistogenes songorica(fractal dimension D0,D2 more closed to 2).
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