[Terrain gradient effects and functional zoning of land use and crop cultivation types in the Red River Basin, Yunnan Province, China].

in total, the planting areas of single cropping rice and sugarcane fluctuated, whereas rapeseed planting decreased. Cultivated land, built-up land, and water bodies were concentrated at low terrain positions (level of terrain position index was 1-3), whereas forests were concentrated at high terrain positions (level of terrain position index was 8-10), grasslands occurred predominantly at mid-to-low positions (level of terrain position index was 1-5). Single-cropping rice tended to expand toward higher terrain positions. Maize was distributed relatively evenly at mid positions. Sugarcane and rapeseed were concentrated at mid and low terrain positions, respectively. The basin could be divided into four functional zones: urban-agricultural coordinated development zone, transitional agro-pastoral composite zone, ecological forestry and steep-slope management zone, and natural ecological conservation zone. The findings would provide a scientific basis for regional land use planning and agricultural structural adjustment.