Evolution of Landscape Ecological Risk and Identification of Critical Areas in the Yellow River Source Area Based on LUCC

A reasonable evaluation of the ecological risk status of the landscape in the Yellow River source area is of practical significance for optimizing the regional landscape pattern and maintaining ecosystem function. To explore the regional heterogeneity of ecological risk in the watershed landscape, a landscape ecological risk evaluation model is constructed to evaluate the ecological risk status of the watershed for 20 years, and correlation analysis is used to further reveal the characteristics of the relationship between ecological risk and land use. The results show that the rapid expansion of urbanization and the increasing intensity of land development and use has caused significant changes in the Yellow River source area ecological environment and various land use types. The area of grassland decreased the most, by a total of 6160.04 km(2), while the area of unused land increased the most, by a total of 2930.27 km(2). A total of 12,453.11 km(2) of land in the Yellow River source area was transformed, accounting for 9.52% of the total area. The most significant area of grassland was transferred out, accounting for 49.47% of the transferred area. During the study period, the proportion of area in the low-risk zone decreased from 54.75% to 36.35%, the proportion of area in the medium-low-risk zone increased from 21.75% to 31.74%, and the proportion of area in the medium-high-risk and high-risk zones increased from 10.63% to 14.38%. The high-risk areas are mainly located in areas with fragmented landscapes and are vulnerable to human activities. The mean ecological risk values in the study area show an increasing trend, and the spatial distribution shows a hierarchical distribution of "lower around the center and higher in the center". The global Moran's I index is higher than 0.68, which indicates that the ecological risk values have a significant positive correlation in space, the area of cold spots of ecological risk varies significantly, and the spatial pattern fluctuates frequently, while the spatial distribution of hot spots is relatively stable. Therefore, the landscape ecological risk in the Yellow River source area is rising, but the different risk levels and their spatial aggregation patterns and cold and hot spot areas continue to transform, which requires continuous planning of the landscape pattern to enhance the safety and stability of the regional ecosystem.