Hydrological mechanisms and vegetation–soil moisture decoupling in restored alpine grasslands of the Qinghai-Tibet Plateau mining areas

The alpine grassland ecosystem of the Qinghai-Tibet Plateau plays a critical role in maintaining regional water conservation functions and ecological security. However, mining activities have caused severe degradation to alpine grasslands, and current understanding of vegetation reconstruction and soil moisture coupling relationships under different restoration approaches remains limited for the fragile alpine ecosystems in Qinghai-Tibet Plateau mining areas, particularly lacking empirical studies based on continuous monitoring data. This study employed automated soil moisture-temperature monitoring systems combined with vegetation surveys, using structural equation modelling and random forest methods to systematically compare vegetation-soil moisture coupling characteristics among native grassland (NG), artificial grassland restored with imported soil (AIS), and artificial grassland restored with land levelling (ALL) in alpine grassland mining areas. Results showed that artificially established grasslands after mining activities exhibited 36.2%-89% biomass decline and a total of 15 plant species were lost, with complete disappearance of the key functional group Cyperaceae . Soil moisture content at 10-50 cm depth decreased by 13.2%, and water storage capacity declined by 16.3%-45.4%. Different restoration approaches showed differential effects: vegetation coverage of AIS was 3.7-10.3 times that of ALL, while the latter achieved higher soil moisture content through mine tailings particle size regulation. Structural equation modelling confirmed the dual effects of vegetation restoration on soil moisture, revealing the mechanisms of mine tailings particle size regulation and plant root systems in grassland water storage recovery. This study elucidates the vegetation-soil moisture decoupling patterns in artificially restored mining grasslands, providing a scientific basis for developing differentiated restoration strategies that balance vegetation establishment and water conservation. • Reveals the asynchrony between vegetation restoration and soil moisture recovery in mining areas. • Quantifies dual effects of vegetation restoration on soil moisture via structural equation modelling. • Identifies pros and cons of imported soil method and direct seeding method for mining area restoration. • Provides differentiated adaptive strategies for balancing revegetation and water conservation in mining areas.