基于地形梯度的三峡库区景观生态风险特征

景观生态风险评价可以较好地反映外界压力源对生态系统的负面影响，分析景观生态风险等级在地形梯度上的分布特征，可为三峡库区生态文明建设和人类活动管控提供科学依据。利用Landsat(OLI/ETM+)2000年、2010年、2020年影像数据，采用GIS网格法、克里金插值法构建景观生态风险指数模型，选取高程、坡度、地形位指数，基于地形梯度对三峡库区景观态风险等级特征进行了研究。结果表明：(1)三峡库区景观生态风险等级分布呈现较强的空间分异特征，各景观生态风险等级面积呈现动态变化。整个研究期间，低风险区、中风险区、高风险区面积增加，较低风险区和较高风险区面积减少。(2)景观格局发生改变的区域优势分布集中在地形位指数小于1.24的区域。景观生态风险等级变化类型以稳定型为主，其次是前期变化型、后期变化型、反复变化型、持续变化型，在前期和后期景观生态风险等级转化分别呈现为“较高—高—高”“较高—较高—中”型的转换特征。(3)景观生态风险等级地形梯度特征表现为库区上游的低风险区向地形位指数大于0.62的区域扩散较多，较低风险区的分布向地形位指数小于1.03的区域集中，库区中下游的较高风险区则主要向高...

Landscape Ecological Risk Characteristics of Three Gorges Reservoir Area Based on Terrain Gradient

Landscape ecological risk assessment can better reflect the negative impact of external stressors on the ecosystem, and analyze the distribution characteristics of landscape ecological risk levels on the terrain gradient, which can provide scientific basis for ecological civilization construction and human activities control in the Three Gorges reservoir area. Based on Landsat(OLI/ETM+)image data in 2000, 2010 and 2020, the landscape ecological risk index model was built by using GIS grid method and Kriging interpolation method, and the characteristics of landscape risk grade in Three Gorges reservoir area were studied by selecting elevation, slope and topographic index. The results show that:(1)the distribution of landscape ecological risk grades in the Three Gorges reservoir area showed strong spatial differentiation characteristics, and the area of each landscape ecological risk grade showed dynamic changes; during the whole study period, the areas with low-risk, medium-risk and high-risk increased, while the areas of lower-risk and higher-risk areas decreased;(2)the areas where the landscape pattern changed concentrated in areas where the topographic index was less than 1.24; the change type of landscape ecological risk level was mainly stable, followed by early change type, late change type, repeated change type and continuous change type; in the early and late stage, the transformation of landscape ecological risk level was characterized by ‘high-high-high' and ‘high-high-medium', respectively;(3)the characteristics of landscape ecological risk grade terrain gradient showed that the low-risk areas in the upper reaches of the reservoir area spread more to areas with topographic index greater than 0.62, and the distribution of low-risk areas concentrated in areas with topographic index greater than 1.03, while the higher-risk areas in the middle and lower reaches of the reservoir area mainly transformed into high-risk areas and medium-risk areas, with the areas transformed into high-risk areas concentrated in areas with topographic index less than 1.03 and those transformed into medium-risk areas concentrated in areas with topographic index less than 1.03. On the whole, the risk value of landscape ecology in the Three Gorges Reservoir area has increased, and the overall ecological environment has been under great pressure. The changes of landscape pattern concentrated in the early stage and the areas with topographic index less than 1.24.