| Wetland is called "the cradle of mankind'\ "a gene pool of living things" and "the kidney of nature " because of huge productiveness, ecological and environmental values. Wetland, forest and ocean are the three most important ecosystem on earth. With the violent increase of world population and rapid development of economy, wetland degrades for the changes of ecological character in wetlands ecosystem including decrease in wetland area, water pollution, biodiversity reduction and weakened function of wetland for mankind disturbing since 20th century. Some effective measures are adopted to prevent the degradation of wetland in many countries around world and the study on restoration and rebuild of degraded wetland ecosystem has been a focus in the past 20 years. Many works have been done in studying wetland ecosystem in plain and northern peat land, but little is reported on the same work at Qinghai-Tibetan Plateau in China, which is one of the most sensitive areas on global climate chnge in the world.Ruoergai wetland lying in the north-eastern part of Qinghai-Tibetan Plateau in China, covers an area of 1 million hm2 including moor, carex swamp, lakes and wet prairie. The global meaning of biodiversity and the important role on global climate change are ensured at the region because of vast area of high altitude moor land rare in the world. However, the excessive human activities resulted in the changes of wetland ecological character, the weakness ofwetland function, wetland soil degradation or desertification during half a century. Since 1990's, some measures of ecological restoration have been taken and the ecological environment has been improved. On the other hand, the people's health and the development of livestock husbandry are damaged due to the selenium response symptom (SRS) in the region, which is one of the five big pastoral areas in China.As was stated above, State Forestry Administration(SFA) began to carryout an international cooperated project------The biodiversity protection ofwetland and its sustainable utilization in China (Project No.:CPR/98/G32/A/lG/99), which was from three units including People's Republic of China (CPR),United Nations Development Program (UNDP) and Global Environment Fund (GEF) in 1999. The purposes of the project were to resolve question on protection and foundation restoration of wetland at four places (Sanjiang Plain,Ruoergai Plateau,Yian Cheng and Dongting Lake) where there were significance of the global biodiversity protection in China. This study was a part of the project and several ecological characters and changes of soil C and Se in the process of wetland ecological restoration were researched to require related information for the project in Ruoergai Plateau. Based on analysis of the changes of wetland water, vegetation, soils and economic development by field investigating, the study pointed out the important effects of ecological character change on the restoration, conservation of water and anti-drought in wetland ecosystem, also the influences of wetland ecological environment on accumulation and distribution of soil organic C, C fixation of wetland plant from atmosphere, and effect of C in wetland ecosystem using a field decomposition approach based on changes of quantity, formation and quality of soil organic matter, and C flow from plant to soil to provide theoretical foundation for the ecological restoration and resources utilization of wetland in Ruoergai Plateau. By studying the quantities and species, distribution of soil Se, the relationships between wetland ecological circumstances and Se efficiency, the effects of Se on growth, Glutathione Peroxidase (GSH-Px) activity and root activity of ryegrass (L. muliflorum Lamaubadd), it also explored the effective utilizing way of wetland soil Se under Se deficiency and the essentiality of Se on rye grass using a method of pot experiment to give a scientific guide of preventing and curing the SRS. The main research results were as follows:1. A series of ecological measures had...
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