The natural restoration of degraded rangeland ecosystem in Heshan hill land
鹤山退化草坡生态系统的自然恢复

This study examined the 20 years trend of natural restoration of a degraded grassland ecosystem in Heshan hilly land.In the past two decades,rangeland research in Heshan has mainly focused on plant succession and soil development.More recently,mechanisms studied have been attempted to explain the initial plant colonization on hilly land,as well as community and ecosystem recovery after disturbance.The results showed that herbs and shrubs were the dominant plants in the community and only a small number of the shade-intolerant tree species had invaded.It showed the characteristics of assembly of pioneer communities.The organic carbon content,soluble nitrogen,available phosphorus,and available potassium had recovered to the level of the local climax community.Part of the ecological functions such as water and soil conservation had recovered.While the functions of water and soil conservation recovered first,more time was needed for productivity and other functions to completely recover,suggesting the idiosyncratic nature of different ecosystem variables in response to time and climate change.Particularly,nutrient cycling recovered very slowly by natural restoration and artificial plantation may be necessary to accelerate the restoration process.