放牧强度对无芒隐子草小尺度空间分布特征的影响

Effects of Grazing Intensities on Cleistogenes songorica Spatial Distribution Characteristics at Small Scales

为了研究荒漠草原无芒隐子草(Cleistogenes songorica)空间分布在不同放牧强度下不同尺度上的变化规律及其斑块特征,以内蒙古荒漠草原为研究对象,在对照区(CK)、轻度放牧(LG)、中度放牧(MG)和重度放牧(HG)条件下,选择2m×2m的代表性样方,记录无芒隐子草株丛的相对坐标,然后划分不同尺度并计算密度,再重新建立相对坐标并采用地统计分析方法进行分析,结果表明:荒漠草原无芒隐子草空间分布随着空间取样单元尺度的增加其缀块性减弱,CK区斑块主要在10cm×10cm尺度上,LG和HG区斑块主要呈现在20cm×20cm尺度上,而MG区在25cm×25cm尺度上的斑块性依然强烈;在LG和MG区,无芒隐子草空间分布比较复杂,空间异质性强烈;无芒隐子草空间分布主要受结构性因素主导,整体表现出随放牧强度增加异质性减弱的变化趋势。

In order to study the change regularity and patch characteristic of Cleistogenes songoricaspatial distribution at different scales under different grazing intensities in desert steppe,2 m×2 mclassical quadrats in representative area at each plot were selected,including control check（CK）,light grazing（LG）,moderate grazing（MG）and heave grazing（HG）in desert steppe of Inner Mongolia.The relative coordinates of C.songorica individuals were recorded in the quadrats and the density were calculated at each space unit.Then the relative coordinates of C.songorica were reestablished,analyzed with geostatistical analysis method.The results were as follows：the patchiness of C.songorica spatial distribution reduced with increasing the scale of spatial sampling unit,the patchiness in CK plot mainly presented in10 cm×10 cm scale,in LG and HG plot mainly presented in 20 cm×20 cm scale,whereas the patchiness in HG remained strong in 25 cm×25 cm scale;In LG and MG plot,C.songoricaspatial distribution was complicated and spatial heterogeneity varied dramatically;The spatial distribution of C.songorica was mainly dominated by structural factors,and it showed a tendency of reduced heterogeneity with increasing grazing intensity.