内蒙古羊草群落、功能群、物种变化及其与气候的关系

基于1981-1994年内蒙古羊草草原的群落学调查数据和同期气象资料,分析了羊草草原群落、功能群与主要物种变化及其生物量与气候的关系.结果表明,1981-1994年5月羊草群落多样性指数、优势度指数、丰富度指数、群落高度、群落生物量的年际变异显著高于其他月,其中羊草群落生物量的变异性自5-9月依次降低,生物量和多样性不存在显著相关性.羊草群落、功能群、物种的年际变异依次增大；不同功能群中一二年生草本和中生植物的年际波动最大,不同物种间的均衡效应降低了群落的变异性.羊草群落生物量具有气候累积效应,主要受上年10月至当年12月的均温、4-8月降水、上年10月至当年8月累积降水的影响,表明羊草群落生物量变化由不同时段的水热因子协同作用决定.

Variations of Leymus chinesis community, functional groups, plant species and their relationships with climate factors

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.