Distribution of land use pattern at different terrain gradients in karst area based on GIS: A case in Benxi village,Youyang county

Studying land use change and its spatial expansion along the terrain gradient is of great significance for identifying the direction of land use change and its sustainable use. In this paper, a case study is conducted in Banxi village, Youyang county, Chongqing City. The regional differentiation in natural conditions is quite obvious, the topographic relief is relatively great, and comprehensive and multiple karst landforms are quite developed in the area. The major aims is to study the characteristics of land use pattern in the region and provide reference for adjusting land use structure and ecologic reconstruction in similar karst areas. The land use data in 2002 and 2011 in Banxi village are obtained by means of RS and GIS techniques, on the basic data of the topographic map(2002), land use status map (2002), SPOTS-5 remote sensing satellite images(2011). According to the above study and terrain index, distribution index and comprehensive land use degree index, changes of land use pattern in 2002 and 2011 in Banxi village of Youyang county is studied and the land use degree at that terrain gradient of the studying area is quantitatively analyzed in this paper.The results show that ,(1)the building land and cultivated land are obvious predominant at low terrain niche; the interval of the preponderant terrain niche obviously increased in woodland, and the woodland changes into uniform distribution from clumped distribution;(2)The preponderant terrain niches of the building land, cultivated land and water area as well as unused land generally remained stable during the study period. According to the quantitative expression of land use degree at terrain gradient, terrain niche interval is divided into three sections, i.e. 1-22, 23-47, 48-50, mainly representing the building land and cultivated land level, the forest land level, the barren land level, which occupies 54.23 %, 40.43 % and 5.34 % of the total study area respectively. Overall, the expansion forest land enables rocky desertification at high terrain to be controlled to some extent. In order to realize reforestation and ecological environment improvement quickly, dominant tree species at scrublands should be fostered and economic forest trees should be inter-planted in still preserved slope cropland focuses in 2011.