Abstract: By stepwise regression analysis, the relationships between soil factors and plant community characteristics, such as biomass richness, diversity and evenness, in western Songnen saline-alkaline grassland were studied during May and September. These plant community characteristics were simultaneously influenced by several soil factors, which changed complexly in different months. Soil salt and nutrition factors all influenced plant community biomass from May to July. However, soil salt factors had more relationship with plant community biomass, such as Ca²⁺ content in May, Mg²⁺ content in July. In the whole growth time, direct effects on plant community biomass from soil salt factors were more than those from soil nutrition factors. In June, the number of soil nutrition factors became more, which influenced plant community richness, Simpson index and Shannon index. Among those soil nutrition factors, the effect of content of total N was the largest. In August, plant community biomass, Simpson index and Shannon index were only influenced by soil salt factors, of which the relationships between biomass and soil pH and between Simpson index and soil ESP were both highly significantly negative correlation, the relationship between Shannon index and soil salt content was significantly negative correlation. Plant community evenness during June to September was also influenced by soil salt and nutrition factors, and soil salt factors had more direct effect in June and September. Plant community biomass had no obvious relationship with soil factors in the end of growth time (in September). No obvious relationship either existed between plant community evenness and soil factors in the beginning of growth time (in May).

Key words: Songnen saline-alkaline grassland, plant community, soil factors