三江源地区退化高寒矮嵩草草甸剥蚀坑的成因

Mechanism of denuded pits developing in degraded alpine Kobresia humilis meadow in the Three Rivers Source Region

以三江源高寒草甸为对象,研究了退化草地剥蚀坑发生的阶段、区域、形成过程及发生机制,并就剥蚀坑发生对草地生产-生态服务功能的影响作了评述。结果表明:剥蚀坑发生于三江源黄河区域高寒草甸小嵩草群落时期,土壤草毡表层的极度发育、老化与死亡是剥蚀坑发生的前提,死亡草毡表层中植物根系的分解、风蚀引起土层的塌陷是剥蚀坑形成的过程。剥蚀坑的发生导致草地系统水分涵养和地球系统碳储蓄功能的降低。保持适当厚度草毡表层是维持高寒嵩草草甸稳定性的基础。

Occurrence of denuded pits in large area is a typical surface feature of the degraded alpine grasslands in the Three Rivers Source Region.The alpine Kobresia humilis meadow was selected as the research object to analysis the characteristics,developing process,occurrence mechanism of denuded pits in research area and discuss its impacts on the productivity and ecological service function.It indicated that the denuded pits take place in cracking period of Kobresia pygmaea meadow phrases,and widely developing in source region of the Yellow River than in the Yangtze River;Denuded pits forming is the synthesized result of dead plant root decomposition,clay erosion and collapse.It tremendously reduced the potential of water holding and carbon storage of alpine meadow ecosystem.It is the key for maintaining the stability of alpine Kobresia humilis meadow to keep a suitable thickness of Mattic epipedon.