放牧对松嫩草原碱化羊草草地植物多样性的影响

Impact of Grazing on Species Diversity on Salinealkalized Leymus chinensis Grassland

松嫩草原碱化羊草草地放牧场植物多样性的研究表明，放牧改变群落内物种的竞争力和环境条件，导致群落类型和种群分布的变化，从而引起植物多样性的变化。随放牧逆行演替的进行，植物种丰富度、植物多样性及均匀度都呈先增后减的变化趋势，适牧阶段最高，极牧阶段也有较大提高。在植被垂直结构方面，由下至上，植物多样性、丰富度和均匀度均呈递减趋势。在上层，过牧和极牧阶段具有较高的多样性指数和均匀度。对主要代表群落的研究表明，羊草群落、角碱蓬群落和羊草－寸草苔群落植物多样性和均匀度都较低，羊草－匍枝委陵菜＋寸草苔群落植物多样性、均匀度和丰富度最高。

eymus chinensis grassland is the main natural grazing land in Songnen, Northeast China.Changes in species diversity under grazing were studied in grazing successional series.The results showed that variety of community types and plant population distribution caused by grazing were the primary factors in changing species diversity.The species richness,diversity and evenness increased from light grazing to proper grazing,then decreased with the increase of grazing intensity,and slightly increased again in grassland extremely over grazed.In respect of profile structure of community,the species richness,diversity and evenness decreased from the bottom of communities to the top.The species diversity and evenness were much higher at the top layer of the communities after over grazing.The results from the main communities showed that the species diversity,richness and evenness of Leymus chinensis-Potentilla flagellaris+Carex duriuscula,L.chinensis-C.squarrosa+C.duriuscula and L.chinensis+Artemisia scoparia-C.vergata communities were much higher than other communities.The species diversity and evenness of L.chinensis,L.chinensis-C.duriuscula and Suaeda corniculata communities were very low.