Response of the Characteristics of Alpine Meadow Plant Community to Disturbance Gradient of Human along Qinghai-Tibet Railway: A Case Study in the Alpine Meadow in Fenghuoshan Area

The alpine meadow communities under different human disturbance in Fenghuoshan area along the Qinghai-Tibet railway were selected to investigation.Five sampling lines were designed and 50 plots were investigated with the sample line transect.Based on the plot data,community characteristics were analyzed,such as the specific composition,the families and genera,the community physiognomy,and so on.In the alpine meadow communities,the frequency index,coverage index and species diversity index(Shannon-Wiener index H′,and Hill index D_1),the richness index(R_0) and the evenness index(E_1) were counted. It is found that the more intense of human disturbance,the more simple of the community composition of the family,genus and species.Along with the increase of human disturbance intensity,the species diversity index and the richness index reduce and the dominate plant species of communities trend from Kobresia pygmaea,K.pygmaea and K.humilis,Poa spp.and Littledalea racemosa,Poa spp.to Festuca spp.and Poa spp.According to the importance value of population responded to human disturbance gradient,the plant species in the area can be divided into 3 response species groups: invasive species group,sensitive species group and tolerant species group.The disturbance gradient was evidently correlative with the content of organic matter,total nitrogen,hydrolyze nitrogen,total phosphorus,readily available phosphorus,but that with total kalium and readily available kalium is not obvious.