Forest soil conservation is pivotal for controlling soil erosion and ensuring ecological security. Taking the Qilian Mountains Area in China as the research region, this study used ArcMap 10.8 software to process data for six prefecture-level cities in the area from 2008 to 2023. The Revised Universal Soil Loss Equation (RUSLE) model was applied to quantify the forest soil conservation amount and evaluate its ecosystem service value (ESV). Their spatiotemporal variations and dynamic evolution patterns were analyzed, alongside the influence of soil organic matter (OM) and nitrogen (N), phosphorus (P), and potassium (K) contents. The results showed that the average contents of OM, N, P and K in the forest soils of the Qilian Mountains Area were 24.22 g·kg−1, 1.54 g·kg−1, 0.70 g·kg−1, and 19.96 g·kg−1, respectively, with significant regional heterogeneity. Haibei Tibetan Autonomous Prefecture (HBTAP) had the highest while Jinchang City (JC) had the lowest. From 2008 to 2023, the average annual forest soil conservation amount and its ESV of the region were 1.749 × 109 tons and 2.0444 × 1010 yuan, respectively, both showing a fluctuating trend of initial increase followed by a decrease. Spatially, HBTAP ranked first in average annual forest soil conservation amount per unit area and ESV. Jiuquan City (JQ) had the lowest forest soil conservation amount per unit area, and JC the lowest ESV. Forest soil conservation and its ESV in the region were affected by the contents of soil nutrients (OM and N, P, K elements), vegetation types and quality, topography, climate, and human activities (including ecological governance), which collectively intensified the spatiotemporal heterogeneity. These findings provide a theoretical basis for precise regional ecological protection and differentiated restoration strategies in arid regions.
Hu et al. (Sat,) studied this question.