A STUDY OF HIERARCHICAL CLASSIFICATION FOR THE STEPPE VEGETATION ON THE SONG-NEN PLAIN
松嫩平原草原植被分类系统的探讨

The Song-Nen Plain is located in the northeast of China. The plain has a temperate semihumid continental climate. The summer is hot and rainy, but the winter is very cold and dry with little snow. The meadow steppe is developed as a result and has become a zonal vegetation type of the region. The combination of plants and distribution of plant communities appear to be controlled mainly by the edaphic condition.From a combination of component species and biotope, using qualitative and quantitative analysis, namely, a polythetic hierarchical agglomerative classification(MULVA-4 PROGRAM),the steppe vegetation on the Song-Nen Plain can be divided into different units. These units are classified as 4 orders, 12 alliances and 40 associations, depending on species composition, especially ecological groups of species, similarity coefficient and dynamic feature of communities, so that a hierarchical system for the steppe vegetation of the Song-Nen Plain is tentatively established. The system reveals the relationship between combination of plant and biotope. The similarity and difference in component species of various units demonstrate not only the whole property but also the continuity and discontinuity of the steppe vegetation.It has been found that there is correspondence between high syntaxa and site type. Based on this correlation the classification of vegetation leads to practical considerations for the management of the steppe in Song-Nen Plain.