Evaluation of Wetland Ecosystem Services in Wuliangsuhai
乌梁素海湿地生态系统服务功能及价值评估

The wetland ecosystem services in arid and semi-arid regions are very important to local environment and livelihood of people. Located in an arid region of northwestern China, Wuliangsuhai is the largest wetland in the valley of the Yellow River. Based on field investigation and statistic data available, a frame of wetland ecosystem services in Wuliangsuhai and methods to evaluate their values are constructed. According to their features, two kinds of ecosystem services are identified: product supply services of direct values and environmental and life support services of indirect values. The main technique for valuing this ecological function of the wetland is the production function approach, and valuing the non-market environmental services through the use of surrogate market valuation. Results show that the direct values including provision of ecosystem products, and recreation and tourism are 0.45×108 RMB, mainly the values of reed production. The indirect values in terms of water resource regulating, wildlife habitat provision, environmental purification, air ingredients controlling, and culture services are 6.68×108 RMB, which is 14.84 times higher than direct values. From above estimated values, it can be concluded that the wetland ecosystem services have great ecological and economic values. The values of wetland ecosystem services in Wuliangsuhai are ranked as follows: regulating air ingredients > water resources regulating > wildlife habitat provision > products provision > environmental purification > recreation and tourism. The function of regulating air ingredients is of the highest value, which indicates that this function is very important in wetlands dominated by emergent macrophytes. The value of regulating water resources is 26.08 percent of the total ecosystem values, and the percentage was lower compared to results achieved in similar researches in other regions. It is indicated that shortage of water resource and eutrophication caused by non-point pollution from Hetao irrigation district are major problems facing Wuliangsuhai to fulfill wetland ecosystem services. The methods applied in the paper are convenient and widely used, but the criteria and principles of evaluation especially for wildlife habitat provision and culture services need to be improved in further studies.