Impacts of land use, rainfall, and temperature on soil conservation in the Loess Plateau of China

In the Loess Plateau, enhancing the function of soil conservation (SC) is essential for maintaining ecological sustainability. Land use (LU), rainfall, and temperature might all have a big influence on SC. In this study, we applied the InVEST model to assess the SC of a typical city, Yan'an, in 1990, 2000, 2010, and 2020. Effects of LU, rainfall, and temperature changes on SC were examined using correlation analysis, redundancy analysis (RDA), regression analysis, and frequency ratio analysis. The findings indicated that farmland (FC), forest land (FL), and grassland (GL) were Yan'an City's main LU types. The expansion of FL and GL areas has come at the expense of the FC areas, partly due to the "Grain for Green" Project, and this change has accelerated considerably since 2000. The total amount of SC in 1990, 2000, 2010, and 2020 generally showed a decreasing and then increasing trend, which was 0.96, 0.87, 1.22, and 1.39 billion tons respectively. In the research region, temperature, rainfall, and LU changes occurred all at once. The FL region was quite consistent with the geographical distribution of areas with low temperatures and heavy rainfall. The results of correlation analysis and RDA indicated that GL area and annual rainfall (PY) were the main causes of SC (p < 0.01). A strong connection (r = 0.63, p < 0.01) was also seen between the daily temperature range (Delta T) and SC. Increased LU-type area, rainfall, and temperature improved SC with a threshold range. Calculated by regression analysis, it recommended the FL <= 11040 km(2), GL >= 14720 km(2), and FC <= 7360 km(2) in Yan'an City. Rainfall and temperature showed no significant pattern and were difficult to regulate by human intervention. The improvement of SC should focus on adjusting the LU structure under the existing ecological planning. Accepting some degrees of uncertainty, our findings provide insights into how possible LU, rainfall, and temperature will affect SC. It's crucial both for future regional management and ecological sustainability development.