A comparative evaluation of rehabilitation approaches for ecological recovery in arid limestone mine sites

Limestone mining in arid regions, particularly within fragile environments, leads to severe environmental pollution and ecological degradation. Developing a scientifically sound and effective ecological rehabilitation strategy is therefore critical. This study constructed a three-dimensional ecological rehabilitation model integrating soil amelioration and vegetation reconstruction. Seven resilient shrub species (Caragana korshinskii, Corethrodendron scoparium, Atriplex canescens, Calligonum mongolicum, Caryopteris mongholica, Nitraria tangutorum, and Tamarix laxa) and four soil matrix reconstruction treatments-sand:soil:organic fertilizer (8:1:1), sand:soil:compound fertilizer (8:1:1), sand:soil (8:2), and soil:organic fertilizer (9:1)-were evaluated for their effects on soil, plant, and microbial indicators. A comprehensive evaluation system was established to identify the optimal rehabilitation approach. The results indicate that organic fertilizer treatments reduced soil EC by 16.39% and increased microbial biomass carbon (MBC), MBC/nitrogen (MBC/MBN), and MBC/phosphorus (MBC/MBP) by over 41.50%, while improving the height and canopy of C. korshinskii by 71.05% and 180.00%, respectively. Plant species significantly influenced soil properties, with T. laxa achieving the highest soil organic matter and total nitrogen content. Soil matrix amendments and plant species both significantly affected microbial β-diversity. Ultimately, the combination of T. laxa and the sand:soil:organic fertilizer treatment was identified as the optimal rehabilitation strategy. These findings provide critical insights for rehabilitating degraded limestone mine areas in arid regions.