Abstract:To study the temporal and spatial evolution law and driving force mechanism of navel orange orchard land, and formulate sustainable land use policy and maintain a good balance between economic development and ecological environment protection in the Three Gorges Reservoir area, Fengjie County of Chongqing, the main production area of navel orange, was selected as the research area, the temporal and spatial evolution pattern of navel orange orchard in Fengjie County from 2000 to 2019 was explored by using multi-source data such as geographical national conditions data and remote sensing images. On the basis of natural and socio-economic categories, policy category was introduced, totally 26 potential factors of pixel and township scales were selected, and then the random forest regression method was used to quantitatively analyze the relative importance of driving factors of land use change in navel orange orchard, and the marginal effects of main factors were also analyzed. The results showed that the navel orange orchard in Fengjie County was expanded rapidly from 2000 to 2019, with an overall scale increase of 150% and an average annual growth of 7.5%. They were mainly distributed along the Yangtze River, Meixi River, Daxi River, Caotang River, Zhuyi River and other main water systems in a zonal distribution, and gradually expanded along the river valley direction. The relative importance of the following driving factors ranked in the top nine were as follows: distance from water source, distance from urban area, soil pH value at pixel scale, and average slope, average elevation, special fund for poverty alleviation of navel orange industry, special fund for modern agricultural citrus industry, science and technology project fund of navel orange industry at township scale and aspect. The contribution of policy factors in the expansion of navel orange orchard was significant, which indicated that more appropriate policies were needed to be formulated to guide the healthy development of navel orange industry. The marginal dependence of navel orange orchard expansion on the main driving factors was strong, and there were differences among different spatial levels. On the whole, the expansion of navel orange orchards tended to occur in areas with average slope of 15°~25°, average elevation of 200~450m, distance from water source less than 3km, soil pH value of 5.5~7.6, financial support and good location conditions. The relative importance of the driving factors of land use/cover change (LUCC) in navel orange orchard was quantitatively analyzed, the driving mechanism of navel orange orchard expansion was explained, and effective technical reference for formulating land use policies was provided to guide the sustainable development of navel orange industry.
