Spatiotemporal evolution of ecological vulnerability in the Yellow River Basin under ecological restoration initiatives

Drought, water shortage, and anthropogenic disturbance bring about serious ecological issues in the Yellow River Basin. In recent decades, the "Grain-for-Green" project, wind-sand control, and water ecological civilization construction are major events affecting the ecological vulnerability in the Yellow River Basin. Based on the "exposure-sensitivity-adaptability" framework and earth observation data, this study proposes an ecological vulnerability evaluation index system that reflects the impacts of natural and human stressors and assesses the ecological vulnerability in the Yellow River Basin during different policy periods. The results show that the overall ecological vulnerability level shows a decreasing trend from 2001 to 2019 in the Yellow River Basin, despite a slight increase in 2015 due to the impact of the dry climate. Medium ecological vulnerability level prevails in the Yellow River Basin. The vulnerability levels have obvious geographical spatial variation. The northern areas in the upper reaches are most vulnerable. Ecological vulnerability in the midstream is better than that in downstream. Ecological restoration policies had an overall positive influence on ecological vulnerability improvement. From 2001 to 2010, the percentages of Heavy (0.60-0.70) and Very heavy (>= 0.70) ecological vulnerability areas in upstream and midstream decreased by 13.3 % under the impact of priority forestry projects. The findings provide guidance for ecological restoration in the Yellow River Basin and the outlined approach is potentially transferable to assess the ecological vulnerability in other regions.