Assessing the relative contribution of climate change and human activity factors to spatiotemporal distributions of sand fixation service in the Loess Plateau

The Loess Plateau is one of the most severely eroded regions in China. Assessing the spatiotemporal changes in wind erosion control services is of significant importance for the ecological protection of the Loess Plateau. The dynamic changes in these services are primarily influenced by human activities and natural climate changes. However, existing studies lack a quantitative evaluation of the contributions of climate change and human activities to the spatiotemporal changes in wind erosion control services on the Loess Plateau. This study utilized a modified soil wind erosion equation and partial derivative method to investigate the response characteristics of wind erosion control service changes on the Loess Plateau to climatic factors and human activities and quantified the relative contributions of these two driving factors. Additionally, the key threshold points of precipitation and grazing affecting soil wind erosion were found by constraint-line method. The results indicated that the amount of the sand fixation per unit area on the Loess Plateau increased slowly at a rate of 0.05 t·hm−2·a−1 from 2000 to 2013 and then increased at a rate of 0.97 t·hm−2·a−1 from 2013 to 2020. Spatially, 47.55% of the area showed an increasing trend, while 41.32% of the area showed a decreasing trend. Overall, the contribution of climate change to the variation in sand fixation services on the Loess Plateau is greater than that of human activities, but their contributions exhibit spatial heterogeneity. In the A2, B1, and B2 subregions, the decrease in sand fixation services and the increase in the A2 subregion are primarily influenced by human activities. Between 2000 and 2020, the average contributions of wind speed and precipitation to SR (sand fixation per unit area) on the Loess Plateau were 0.243 t·hm-2·a-1 and 0.09 t·hm-2·a-1, respectively, making them the most significant climatic drivers of SR changes. In coal mining areas on the Loess Plateau, the amount of the sand fixation per unit area mainly showed a decreasing trend (52.30%), while the conversion of cropland and unused land to grassland significantly promoted an increase in the amount of sand fixation, accounting for 50.30% of the total increase. After grazing intensity reaches a threshold (around 13.51%–35.84%), SR declines rapidly with further increases in grazing intensity. Various major ecological projects have also significantly promoted the increase in wind erosion control. The study results can pr