黄土高原区主导生态风险识别及分异性研究——以黄河流域中游为例

黄河流域作为典型的生态脆弱区，其生态问题复杂多样，亟待全面的生态治理和修复。同时，黄河流域生态保护和高质量发展是当前我国发展战略之一。明确黄河流域存在的生态问题，做好区域生态修复，开展综合治理是黄河流域可持续发展的重点。因此把握黄河流域的自然条件的区域差异，开展综合性的生态风险识别与评价，明确区域风险空间异质性分布与特点，是服务于区域生态修复、促进黄河流域高质量发展的重点。结合黄河流域中游气候、地形、植被等多自然本底情况识别风险源，建立服务于研究区生态保护和修复的区域生态风险评价体系，并通过GEE和GIS平台，可视化和量化了各类生态风险，并采用空间相关分析明确了生态风险的主要成因。结果表明：1）研究区的生态风险空间分布具有显著的区域特征，各个要素的生态风险呈现明显的东南和西北的差异、不同土地覆被情况的差异、人类活动带与非人类活动带的差异以及河流沿河与非沿岸的差异；2）植被净生态系统生产力呈现东南高西北低的特征，温度植被干旱指数显示西北部、山西、陕西南部存在较高的干旱风险，土壤侵蚀风险主要存在于黄河沿岸、其他河谷地带以及西北部，防风固沙服务能力在山西省山区以及植被生长较好的地区较高；3）综合生态风险评价显示宁夏以及陕西北部多数地区属于高风险区，低风险区主要分布在研究区西南部以及山西省西部沿线地区；4）双变量的Moran''s I指数显示地表温度、植被覆盖和汛期降水是导致综合生态风险西北和东南差异的主要原因，坡度是导致局部风险差异的主要原因。

Identification and differentiation of dominant ecological risks in the Loess Plateau: A case study of the middle Yellow River Basin

As a typical eco-fragile region crossing northern China, the Yellow River Basin has complex and diverse ecological problems and is in urgent need of comprehensive ecological governance and restoration. Meanwhile, the ecological protection and high-quality development of the Yellow River Basin is one of the current development strategies in China. In order to achieve sustainable development of the Yellow River, it is necessary to identify the existing ecological problems, and then carry out regional ecological restoration and comprehensive management. Therefore, grasping the regional differences of the natural conditions in the Yellow River Basin, carrying out comprehensive ecological risk identification and evaluation, and clarifying the spatial heterogeneity distribution and characteristics of regional ecological risks are key points to serve regional ecological restoration and promote high-quality development in the Yellow River Basin. Ecological risk assessment as a method to quantify complex ecological risks can provide decision makers with quantification and visualization of risk scenarios. This paper takes the middle reaches of the Yellow River Basin-Loess Plateau area as the study area. We identify risk sources by combining multiple natural background conditions such as climate, topography and vegetation in the middle reaches of the Yellow River Basin. A regional ecological risk assessment system serving the ecological protection and restoration through Google Earth Engine and GIS platforms has been established to analyze the spatial heterogeneity of various types of ecological risks and clarify the main causes of ecological risks by the method of spatial correlation. The results show that:1) Four categories of ecological risk factors spatially clearly reflect regional issues. The spatial distribution of ecological risk in the study area has significantly regional characteristics. Firstly, there is a significant difference in ecological risk between the southeast and northwest of the study area. Secondly, there are differences in ecological risks under different land cover types. Thirdly, there are also significant differences in ecological risk between anthropogenic and non-anthropogenic zones. Finally, there are also differences between riverine and non-riverine shores. 2) In terms of the spatial distribution of the four categories of ecological risk factors, the net ecosystem productivity of vegetation shows characteristics of high in the southeast and low in the northwest. The temperature vegetation dryness index shows that there is a higher risk of drought in northwestern areas, Shanxi and southern Shaanxi. The soil erosion risk mainly exists along the Yellow River, other river valley areas and in the northwestern area. The services of windbreak and sand fixation is higher in mountainous areas and areas with better vegetation condition in Shanxi Province. 3) The comprehensively ecological risk assessment shows that most areas in Ningxia and northern Shaanxi are in the high-risk status, and the low-risk areas are mainly located in the southwestern study area and along the western Shanxi Province. 4) The bivariate Moran index explains the spatial drivers of ecological risk, which shows that surface temperature, vegetation condition and flood season precipitation are the main causes of the differences of comprehensive ecological risk between the northwestern and southeastern parts of the study area, and slope is the main reason for the regional difference in ecological risks.