Change Of Farmland Ecosystem Services Values And Its Driving Forces In Northwestern Arid Area

Ecosystem services were the foundation of human existence and the source of human welfare. Cultivated land was the essence of land resources and the support of farmland ecosystems. The quantity and quality of cultivated land were the basis of farmland ecosystem services and functions.Minqin County, located between Badain Jaran Desert and Tengger Desert, was an epitome of Chinese arid area and West China's fragile ecological environment. Recently, due to climate change and increased intensity of human activities, land degradation (land salinization, desertification), decline of vegaetation and shortage of water has becoming the most serious problems to restrict the development of local agriculture and economy. Based on the theories and methods of ecosystem services, the datas from Minqin County's economic and social development, qualitative and quantitative methods was used in this paper to explore the process of change of Minqin farmland area,farmland ecosystem services and its driving forces. The preliminary study results were listed as below in detail.(1) Change of farmland area of Minqin countyThe arable land of Minqin county has changed as a fluctuation in the pasted 60 years as rapid increase-fast decrease-slow decrease-slow increase-frequent fluctuation. The change trend can be divided into seven periods, such as, rapid increase from 1949 to 1956,rapid decline during 1957-1962, slow decrease from 1963to 1970, slow increase from 1971 to 1979, slow reduction from1980 to 1984, slow increase during 1985-2000 and frequent fluctuation from 2001 to 2008. As to the cultivated land area per person, it changed as a rapid increase-rapid reduction-decline slowly in the pasted 60 years. It can be divided into three periods such as, fast decrease from 1949 to 1955, quick increase from 1956 to 1963 and increase from1964 to 2008.(2) The principal driving forces of arable land changeThe principal component analysis results showed that the driving forces of cultivated land change can be summarized as socio-economic development, agricultural technology, water use (the contribution rate of the former three factor is 72.28%), and the and meteorological factors and environmental factors has a contribution rate of 15.75% to cultivated land change.(3) Spatial change of cultivated land of Minqin countyThere was a significant difference of the spatial distribution and area of cultivated land of Minqin county. There was an apparently decrease of cultivaed land during 1978 to 2000 in many townships, such as, Xuebai, Sushan, Dongba, Jiahe, Datan, Quanshan, Xiqu, Donghu, Shoucheng. The relative change rate of Changning, Sanlei, Daba, Hongshaliang, Hongshagang and Nanhu were larger than 1, the change of the whole county.During the period of 2001 to 2008, the cultivated land area of Xiqu, Donghu, Shoucheng, Shuangcike were decreased. And the other township has an opposite trend. In addition to Shuangcike village, Sanlei town and Hongshaliang village, The relative change rate of all the township were larger than 1 except Shuangcike, Sanlei and Hongshaliang, that is, the relative change rate were larger than that of the whole county.(4) Change of farmland ecosystem service value of MinqinMinqin County farmland ecosystem service value was 12.8×108 and 12.93×108 yuan a-1 in 2000 and 2008, respectively. Coefficient of different development and the scarcity of ecological resource were used to rectify ecosystem service value. And the rectified ecosystem services value were 16.39×108 and 24.19×108 yuan a-1 of 2000 and 2008, respectively. It can be drawn the conclusion that socio-economic development level and the amount of water resource had a major impact on willingness to pay for ecosystem service. The developed of economy and the scarcer of resource, the higher of willingness to pay for ecosytem service, vice versa. (5) Spatial change of farmland ecosystem servicesThere were some significant differences of farmland ecosystem service value amont the different township in Minqin county. There was a decrease of ecosystem services value of township of Dongba, Suangcike, Xiqu, Donghu, Shouchengand Hongshaliang from 2000 to 2008, and the other township has an increase of ecosystem service from 2000 to 2008. The change rate of ecosystem service value of Sanlei, Dongba, Shuangcike, Hongshaliang were smaller than that of Minqin county.(6) The main driving forces of farmland ecosystem service value changeIt can be drawn that farmland ecosystem service value change had been mainly coeffected by climate change, water resources, socio-economic development, scientific and technological progress, and so on.