放牧干扰对东祁连山高寒草地植物群落物种多样性的影响

放牧干扰是改变草地植物群落物种多样性的主要因素之一。通过研究东祁连山高寒草地放牧干扰梯度对植物群落物种多样性的影响,结果表明,放牧过程中,牲畜的啃食、践踏等作用干扰了草地环境,改变了群落内物种的竞争力和环境条件,使群落类型和种群组成与分布发生变化,物种优势地位发生更替,从而引起植物群落多样性的变化。随着放牧强度的增大,群落丰富度逐渐下降。多样性指数在中牧或重牧阶段达最大值,过牧阶段也较高,略有所增加, 主要是由于群落均匀度的增加。生活型功能群也表现出了明显的变化。放牧干扰对草地生态系统是一种常见现象,是推动草地生态系统进化和演变的外在驱动力。其利弊取决于干扰本身的性质、强度以及草地群落的结构特征,适度的放牧干扰可以促进物种多样性的维持与保护。

Effect of grazing disturbance on species diversity of alpine grassland plant community in Eastern Qilian Mountains

Grazing disturbance is one of main factors affecting species diversity of grassland plant communities. The species diversity was studied along grazing disturbance gradient of alpine grassland in the Eastern Qilian Mountains. The results showed that the grazing disturbed pastureland environment due to gnawing and treading of livestock, which changed plant species composition, population dominance and variety of community types,and then caused the changes of species diversity. As a consequence, the species richness of different communities were gradually lowered with the aggravating of grazing intensity. The species evenness and diversity indices reached the highest in heavy degradation or moderate degradation stages,and slightly increased again in over degradation stages and were related to the species evenness increases of the different communities. Life form also manifested some obvious changes along grazing disturbance gradient. Grazing disturbance was a common phenomenon, and also was the external driving function for the grassland ecosystem as it pushed forward the evolution and development of grassland ecosystem. Grazing disturbance had positive or negative effects on vegetation and was sometimes helpful for species diversity maintenance and conservation.