Analysis on the socio-economic driving forces of land use changes in mountain area

The Upper Reaches of the Heihe River is the water source of the whole Basin, in which the way of land use different from the middle and lower reaches of the Heihe River because of particular natural features and human activities. The variation processes of the land use structure in the Upper Reaches of the Heihe River have an important effect on water resources and ecosystem of the whole watershed. The methods of remote sensing image analysis, transfer matrix and principal component analysis were employed in this paper to analyze quantitatively the course of spatial and temporal variations of three main types that woodland, grassland and cultivated land in mountain area of the Upper Reaches of the Heihe River Basin. The artificial motivation of land use changes in the study area had been indicated. The results showed: (1) the variation stages of land use demonstrated clearly in the study area, in which three kinds of land use types as cultivated land, grassland and forest land had transformed obviously in two stages of 1987-1999 and 1999-2010, that is, the area of forest decreased continuously, the area of grassland decreased at the first stage and then increased at the second stage, the cultivated land increased sharply; (2) spatial variation of single land of three types was remarkable, the distribution of forest land presented acreage in the eastern part more large than western and southern less than northern part; the area of grassland were the largest, and distribution patterns of it display more in eastern and more in south; the area of cultivated land were the least, they mainly distributed along the valleys of the Heihe River, and (3) the forest and grassland degraded seriously. The main causes of land degradation in the area under study led by population increase with excessive use of land.