D.W.Goodall 对分级法所作的定义为:“各单元按一种或多种分类标准的大小次序排列的方法”。此法虽不能表示相关原因,伹可以作为许多复杂因子所产生的主要效果的指标。基于此理,J.T.Curtis 确定了威斯康辛州植物群落的相似度并将其划分为2个或3个分类标准。Curtis 及其它生态学者建议,用数 D.W. Goodall’s definition of grading is: “The way in which cells rank according to the size of one or more taxonomies.” Although this law can not indicate the relevant reasons, 伹 can be used as an indicator of the main effects of many complex factors. Based on this rationale, J.T. Curtis identified the similarity of the plant communities in Wisconsin and classified them into 2 or 3 taxonomic criteria. Curtis and other ecologists suggest using numbers