---

作 者 ：Li Jian-dong and Zheng Hui-ying

Keywords:Song Nen plain: Ecological group of species, Plant community, Site type,

Abstract:Song Nen plain is located at the northeast of China The south of the plain is characterized by temperate semimoist continental climate. Summer is hot and rainy, but winter is cold and snowless. In the region, the meadow steppe developes and has become a zonal vegetation type. During the 1982–1984 sampling of 286 sites was done, recording abundance coverage, sociability (according to Braun Blanquet) of vascular plant species, along with the soil characteristics. The correlation of vegetation and environment has been used to analyse ecological response of the plant species of plant communiies to enviromental conditions. The distribution and growth rate of plant species are largely determined by salt content, alkalization, and water content in the soil Tile organic matter, nitrogen, and pH in the soil are secondary factors influencing the distribution of plant. It has been found that there is usually a similarity of the ecologic, al response of many species to single or a group of above mentioned factors. According to these similarities, life form and combination index, the main plants in the research area can be divided into ecological group of species. These ecological groups of species are essential for understanding the ecological basis of plant communities and their relation to environment. Therefore the correlation of ecological group of species plant community and environment could be used as a basis for classifying site types, It can divide site types in the research area. The results show that the ecological groups of species not only reveal the relationship between vegetation and environment but also can be used as a basis for classification of site types and lead to practical consideration of the management of steppe in the southern Song Nen Plain.

---