中国东北样带草地群落放牧干扰植物多样性的变化

放牧干扰是草地群落植物多样性变化的主要影响因素之一。中国东北样带9个草地群落放牧干扰植物多样性变化的研究结果表明：中牧或重牧阶段Shannon指数达最大值，形成中牧（重牧）>重牧（中牧）>轻牧>过牧的规律。群落物种丰富度、均匀度与多样性的相关分析表明，均匀度变化对多样性变化具有更大的贡献率，而丰富度呈下降趋势，即轻牧（中牧）>中牧（轻牧）>重牧>过牧。生活型功能群多样性也表现出明显的变化。中国东北样带草地群落植物多样性的分布格局是：草甸草原>典型草原>典型草原 >荒漠草原>碱化草原，并且群落物种丰富度对多样性有更大贡献率。

PLANT DIVERSITY CHANGE IN GRASSLAND COMMUNITIES ALONG A GRAZING DISTURBANCE GRADIENT IN THE NORTHEAST CHINA TRANSECT

Grazing disturbance is one of nain factors affecting change in plant diversity of grassland communities. The results of this study of nine major grassland communities along the grazing disturbance gradient in the Northeast China Transect showed that the Shannon index was the highest in moderate grazing or heavy grazing stages, changing as follows: Moderate grazing-Heavy grazing>Heavy grazing-Moderate grazing)>Light grazing>Over grazing. While species richness had a higher contribution to species diversity, compared with evenness, changes in evenness contributed most towards the rate of change in diversity than did changes in species richness. Life form diversity also manifested some obvious changes along the grazing disturbance gradient. The pattern of plant diversity of the steppe region in the Northeast China Transect was Meadow steppe > Typical steppe > Desert steppe > Alkaline meadow.