Characteristics of carbon, nitrogen, and phosphorus in soil aggregates under different restoration methods on cut slopes in the Qinghai-Tibet Plateau mining area.

Extensive cut slopes resulting from anthropogenic engineering activities in alpine mining areas of the Qinghai-Tibet Plateau have led to soil structure fragmentation and nutrient loss, threatening ecosystem stability. This study systematically compared soil aggregate stability and carbon-nitrogen-phosphorus nutrient characteristics among three restoration methods for cut slopes (three-dimensional netting [TCS], frame beams [FCS], and galvanized wire mesh [GCS]) relative to unrestored cut slopes (UCS) in the Jiama Mining Area, Tibet. The results demonstrated that TCS and FCS significantly increased the proportion of soil macroaggregates (>0.25 mm) by 7.55 %-18.61 %, with significantly higher mean weight diameter (MWD) values (1.10-1.31) compared to GCS and UCS (0.86-1.00) (p < 0.05). TCS and FCS showed significantly higher soil organic carbon (SOC), total nitrogen (TN) content and C/P ratios compared to UCS (p < 0.05). The highest C/N ratios occurred in FCS, while the highest N/P ratios were observed in TCS. Redundancy analysis and a random forest model indicated that macroaggregate content, enzyme activity, and available nutrients were the key factors enhancing soil nutrients. Partial least squares path modeling (PLS-PM) revealed that macroaggregate content and easily extractable glomalin-related soil protein (EEGRSP) directly exerted significant positive effects on soil aggregate stability. In cut slope ecosystems of Qinghai-Tibet Plateau mining areas, FCS and TCS collectively regulated soil pH by maintaining stable aggregate structures and high enzyme activity, thereby influencing the regional nutrient stoichiometric balance. This study demonstrated that ecological restoration in alpine mining areas should prioritize three-dimensional netting and frame beam strategies to enhance aggregate stability and nutrient retention capacity, providing theoretical foundations for adaptive ecosystem management in vulnerable zones.