This paper is the result of ecological geological survey engineering.

Objective To monitor the spatiotemporal distribution characteristics of ecological vulnerability in the middle and upper reaches of the Yellow River Basin, evaluate the status of ecological environment changes, reveal the dominant driving factors underlying variations in ecological vulnerability, and provide a scientific basis for the governance of ecologically fragile areas in the basin.

Methods Taking the middle and upper reaches of the Yellow River Basin as the study area, a comprehensive analysis was conducted using multi-source data including DEM, meteorological data, socio-economic data, remote sensing data, and land use data (CLCD). Nine evaluation indicators were selected, covering topography, meteorology, society, vegetation, and other dimensions. An ecological vulnerability assessment system was established based on the SRP model (Ecological Sensitivity-Ecological Resilience-Ecological Pressure). The indicator weights were determined comprehensively using the entropy weight method and AHP (Analytic Hierarchy Process). Ecological vulnerability was comprehensively evaluated for five periods: 2000, 2005, 2010, 2015, and 2020, to examine its spatiotemporal dynamic characteristics. Furthermore, the dominant influencing factors were identified and analyzed via the Geodetector model.

Results (1) Spatially, slight and low ecological vulnerability was mainly distributed in middle-to-high altitude mountainous areas dominated by forest land; moderate ecological vulnerability was concentrated in middle-altitude loess tablelands, medium-low relief mountainous hills and terraces, covered mainly by shrub-grass vegetation and farmland; high and extremely high ecological vulnerability was primarily distributed in the Mu Us Sandy Land, characterized by unused land. (2) According to factor detection results, the top five factors influencing ecological vulnerability in the study area, in descending order of significance, were Normalized Difference Vegetation Index (NDVI), annual average precipitation, land use type, annual average temperature, and elevation. (3) From 2000 to 2020, ecological vulnerability improved gradually and significantly, with the proportion of high and extremely high vulnerability areas decreasing from 39.43% to 18.32%. In terms of geomorphology, middle-altitude loess tablelands, middle-altitude mountains, and middle-altitude aeolian landforms ranked the top three geomorphic types in terms of the proportion of improved ecological environment area.

Conclusions Ecological vulnerability in the study area exhibits a distinct spatial pattern of low vulnerability in the southeast and southwest and high vulnerability in the central and northwest regions. The overall ecological vulnerability is at a moderate level, and the ecological environment shows an improving trend, which is closely related to ecological restoration supported by socio-economic development.