Organic Fertilizer Effects on Ecosystem Multifunctionality and Trade-Offs in Alpine Mine Reclamation

Reclamation measures are essential tools for enhancing ecosystem functions and promoting ecological sustainability. This study focused on the Jiangnan mining area within the Muli coalfield in Qinghai Province, China. Four organic fertilizer reclamation treatments were established, namely, unfertilized control (CK, 0), low fertilizer (LF, consisting of sheep manure at 165 m3/ha and commercial organic fertilizer at 7.5 t/ha), medium fertilizer (MF, using 330 m3/ha of sheep manure and 15.0 t/ha of commercial organic fertilizer), and high fertilizer (HF, using 495 m3/ha of sheep manure and 22.5 t/ha of commercial organic fertilizer), with a natural meadow near the experimental site selected as a reference for evaluation. Through a field vegetation survey and indoor analysis, the primary productivity, water conservation, carbon cycle, nitrogen cycle, and phosphorus cycle of five ecosystem functions and ecosystem multifunctionality (EMF) were quantified, and the trade-off relationships among ecosystem functions were analyzed. The findings indicate the following: (1) Compared to the unfertilized control, organic fertilizer reclamation significantly enhanced all individual ecosystem functions and EMF, with the EMF value under the high-fertilizer treatment (EMF = 0.69) even exceeding that of the natural grassland (EMF = 0.60). (2) This intervention altered the original trade-off patterns (ERMSD = 0.03), intensifying trade-offs among multiple ecological functions (ERMSD = 0.09), whereas natural grassland exhibited the strongest trade-off intensity (ERMSD = 0.26). In summary, while organic fertilizer reclamation effectively enhances the multifunctionality of alpine mining ecosystems, it also amplifies trade-off effects among ecological functions to varying degrees. Therefore, future long-term positioning observations are required to evaluate the ecological stability and sustainability of this restoration technology under extreme climatic conditions and to further explore reasonable grazing and mowing management plans in order to coordinate multiple ecological functions, thereby promoting the development of the reclamation ecosystem in alpine mining areas toward coordination and health.