1. College of Geography and Tourism, Shaanxi Normal University, Xi’an 710119, China 2. College of Environment and Planning, Liaocheng University, Liaocheng 252000, China
As a key and demonstration area for the implementation of the national ecological project of returning farmland to forestry, Yan’an City is a concentrated area of ecological problems in China. It is of great significance to study the spatial and temporal differences of land ecological risks for the sustainable development of regional land and the formulation of differentiated land and resources development policies. According to the basic characteristics of land ecosystem, four risk indicators, namely vegetation coverage, percentage anomaly precipitation, land use structure risk index and soil erosion index, were selected to construct a comprehensive evaluation model of land ecological risk. Then on the basis of pixel scale, each factor index and comprehensive index of land ecological risk were calculated. In combination with exploratory spatial data analysis (ESDA), the spatial and temporal evolution of land ecological risk and spatial agglomeration effect in Yan’an City from 2000 to 2015 was analyzed. Then the corresponding suggestions for comprehensive management of land in different regions were put forward. The results are as follows: The land ecology of Yan’an City is in good condition as a whole, whereas the land comprehensive ecological risk and the risk of the four ecological factors temporally decrease on the whole; nevertheless, the area of Baota District and Luochuan County is higher in this aspect, and high comprehensive risk areas increase slightly. The land comprehensive ecological risk of Yan’an City shows a strong spatial agglomeration. Hot spots include urban hot spots located in urban construction areas and northern hot spots distributed in five districts and counties of Zichang County, Ansai District, Yanchuan County, and Wuqi County. The cold points are mainly located in Huanglong County, Yichuan County, Huangling County, Fuxian County and the southwest area of Ganquan County. Thanks to the implementation of national eco-engineering measures such as returning farmland to forestry (grassland) and closing hillsides for reforestation, the agglomeration degree of hot spots has been gradually weakening. However, the area of urban hot spots in Baota District continues to increase, and hence attention should be paid to strengthening ecological management. As cold spot areas in northwest Fuxian and western Yichuan County has been shrinking because of climate drought, attention should be paid to optimizing the allocation of water resources.
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