Variations of Leymus chinesis community, functional groups, plant species and their relationships with climate factors
内蒙古羊草群落、功能群、物种变化及其与气候的关系

Inter-annual variations of Leymus chinensis community, functional groups, plant species and their relationships with climate factors were analyzed in this paper based on a series of investigation data (1981-1994) together with related meteorological data. The results showed that the main species of Leymus chinensis community are perennial grass and xerads, which were mainly induced by the semi-arid climate conditions. During 1981-1994, the variability of the above-ground biomass which is the highest among the indices declined from species, functional group to community level, with the most significant variation in annual and biennial as well as the mesophytes. It was implied that the xerads in this semi-arid area is adaptable to the climate and the biennials could not put remarkable impact on the community because of its low percentage. The results also indicated that when climate fluctuated, the growth characteristics of plant species were more sensitive than community composition. There was a significant relationship between the biomass of community and perennial grass as well as xerads. It should be noted that different responsiveness leveled off the variation. Especially, the obvious compensatory effects in the dynamics of biomass between dominant species Leymus chinensis and Stipa grandis enhanced community stability. The variability of community biomass decreased from May to September, and there was no significant relationship between biodiversity and biomass. During the whole growing season, grass was more easily influenced on re-greening stage resulting from the simple community structure; grass with peculiar reproductive strategy was relatively stable in the late period of growing season. In order to reveal the shifts of community, the comprehensive analysis of diversity, biomass, species composition, interference, nutrient and climatic factors is necessary. The shift of biomass is relevant to mean annual temperature during last October- December, precipitation from April to August, and accumulative precipitation during last October to August, indicating that it was related to the comprehensive effect of temperature and precipitation.