Spatial differentiation and formation mechanism of ecological sensitivity in large river basins: A case study of the Yellow River Basin, China

Conducting ecological sensitivity assessment is a crucial approach for pinpointing regional ecological environmental issues, which can offer a scientific basis to aid in the prevention of regional ecological degradation and ensuring regional ecological security. With the protection and high-quality development of the Yellow River Basin (YRB) at the level of a national strategy in China, there is a critical need for a comprehensive assessment of the YRB’s ecological sensitivity. To this end, this study aimed to construct a new ecological sensitivity evaluation index system from three perspectives: natural ecosystem, natural-social ecosystem, and social ecosystem. The ecological sensitivity index was quantified using the entire-array-polygon indicator method, and the spatiotemporal changes of ecological sensitivity in the YRB and its sub-basins were analyzed from 2000 to 2020. The optimal parameters-based geographical detector model was employed to delve into the mechanisms driving the spatial variation in ecological sensitivity. We found that (1) from 2000 to 2020, ecological sensitivity in the YRB exhibited a bimodal trend. Spatially, it tended to be low in the western and eastern parts while it was relatively high in the southern and central regions. (2) The YRB displayed notable clustering effects in terms of ecological sensitivity. The source area showed both “high-high” and “low-low” groupings, the upstream area showed a predominance of “low-low” clusters, while the midstream area and downstream area were demonstrated by concentrated “high-high” clusters. However, the clustering effect in downstream gradually weakened over time. (3) The ecological sensitivity of the YRB was primarily driven by factors like shifts in climate change and soil erosion. There were also marked differences in spatial heterogeneity of ecological sensitivity across different sub-basins. Moreover, the influence of interactive factors on the YRB's ecological sensitivity and its sub-basins was enhanced. The research findings enhance our understanding of ecological issues faced by the YRB and establish a foundation for developing strategies to protect and manage its environmental ecosystem effectively.