The Effect Of Species Loss On Community Function In A Tibetan Alpine Meadow

To understand the response mechanism of grassland community function to land use and global change such as grazing,we conducted a systematic species elimination experiment in a Tibetan Alpine Meadow since 2011.The experiment began in 2015 to 2017,in order to discuss the response of species loss on grassland community function,we measured and analyzed the community productivity,community photosynthetic rate,seedling number,ground temperature and relative humidity,and soil temperature in every plot subjected control(CK)or artificial removal of gramineous;kobresia,forbs and all plants.The results show that:(1)As the number of forbs in the community was more,the species richness of the community decreased significantly after the removal of Forbs.Although the biomass of gramineae increased significantly,the total biomass of the community was still lower than that of the control.The variation of photosynthetic rate was not obvious.The daily maximum temperature of soil increased and the daily minimum temperature decreased,which lead the variation of soil temperature and relative humidity increased significantly.Compared with CK,the number and the species richness of seedling were also significant changes due to the loss of forbs.(2)After the removal of gramineae,the biomass of forbs increased obviously,but the total biomass of the community did not decrease because of the loss of gramineae.The elimination of gramineae had little effect on community photosynthetic rate,ground temperature and relative humidity,soil temperature,seedling number and seedling species richness.(3)Eliminating dominant kobresia could increase the total biomass of the community,but the species richness,community photosynthesis rate,ground temperature and relative humidity,soil temperature,seedling number and species richness did not change significantly due to the loss of dominant species.Based on the above results,we conclude that forbs were very important in maintaining the function of community in a Tibetan Alpine Meadow.And the loss of some forbs with high abundance will have a profound effect on the alpine meadow ecosystem.Compared with forbs,the decrease or loss of the abundance of gramineae and kobresia species in the local community had little effect on the function of the community,and might be restored rapidly through asexual reproduction.