过牧对草地生态系统服务价值的影响——以甘肃省玛曲县为例

Effects of Excessive Grazing on Grassland Eco-system Services Valuation

文章以甘肃省玛曲县为例,通过对该县草地状况的分析,以玛曲县20世纪80年代草地状况作为过牧前状态,目前草地状况作为过牧后状态,探讨过牧对草地生态系统服务价值的影响,并通过对该县草地生态系统的分析,建立了过牧对草地生态系统服务价值影响评价指标体系,即食物生产、调节大气、营养物质循环与贮存、控制侵蚀、涵养水源、环境污染净化六大功能。最后运用生态经济学方法对过牧造成的经济损失进行了初步估算。结果表明,玛曲县由于过牧造成的直接和间接经济损失分别为:食物生产1.50×108元,调节大气1.04×109元,营养物质循环与贮存0.99×108元,控制侵蚀1.02×107元,涵养水源3.94×108元,环境污染净化2.9×107元,总经济损失达到1.72×109元,其中,间接经济损失占91.3%。

Grassland eco-system service provides a natural environment condition and function that grassland eco-system forms and sustains human being survival.And it does not only offer raw materials for husbandry,but also some regulating and supporting services.In fact the latter function and their values are most important,but usually neglected.In recent 20 years,excessive grazing has exerted severe negative influence on grassland eco-system services,especially on its environment sustaining service,and the resultant economic losses are very great. Thus this paper discusses the effects of excessive grazing on grassland eco-system services values,by taking Maqu county as an example and analyzes its grassland conditions by taking grassland conditions in the 1980s as pre-excessive grazing and the present conditions as postexcessive grazing.Firstly,based on the analyses of grassland eco-system,the index system of effects of excessive grazing on grassland eco-system services valuation was constructed,including food production,atmospheric regulation,nutrition circulation and storage,erosion control,water conservation and environmental purification.Then by choosing reasonable ecological economic methods and parameters based on other＇s researches,assessment method of every index was established.Finally,using the above methods,the economic losses of excessive grazing were primarily estimated. The results showed that economic losses in food production,atmospheric regulation,nutrition circulation and environmental purification values of grassland in Maqu county in the 1980s were 4.28×10^8 yuan,2.96×10^9 yuan,2.84×10^8 yuan and 8.3×10^7 yuan,respectively, while at present those values were 2.78×10^8 yuan, 1.92×10^9 yuan,1.85×10^8 yuan and 5.4×10^7 yuan,respectively.Due to excessive grazing,the economic losses lation and storage,erosion control,water of food production,atmospheric conservation and environmental regulation,nutrition circupurification services were 1.50 ×10^8 yuan, 1.04 ×10^9 yuan,0.99 ×10^8 yuan,1.02 ×10^7 yuan,3.94 × 10^8 yuan and 2.9 × 10^7 yuan, respectively.The total economic losses reached 1.72×10^9 yuan,in which direct economic losses accounted for 8.7% ,and indirect economic losses were enormous and accounted for 91.3%. Among these services, the values of atmospheric regulation and water conservation services were higher,while those of erosion control and environmental purification services were lower.