| 2. | Using the cluster analysis method and studying 16 sampling plots of shrub grassland where bothriochloa ischaemum is the dominant species , and the plots ' grass frequency , grass coverage , density , height , and biomass , we graded the plots into five grazing stages : light , proper , moderate , serious , and extreme 摘要在对放牧利用下的白羊草灌丛草地频度、盖度、密度、高度、生物量等数量特徵调查基础上,运用系统聚类分析方法,可戒分为轻放、适牧、中牧、重牧和极牧五个阶段。 |