Comparative research on the plant communities of moderate-degraded and heavy-degraded stipa alpine grassland

A study was conducted at the Sanjiaocheng sheep breeding farm of Qinghai province,which is located on the north bank of Qinghai Lake with natural alpine grassland.A comparative research on the plant communities between moderate-degraded and heavy-degraded alpine grassland was conducted,the result showed that with the aggravation of grassland degradation,the coverage,species diversity indexes,evenness indexes of plant communities decreased.The accumulative rate of biomass of plant communities decreaed,leading to primary production decreased.The percentage of fine forages such as grasses decreased with the increasing of forbs.The seasonal change rate of litter appearedas decomposing rate from June to July,and as accumulative rate from August to September.The decomposing rate of moderate-degraded plots was more than heavy-degraded plots and the accumulative rate of moderate-deqraded plots was less than heavy-degraded plots.