Abstract:
Coal mining-induced surface cracks and subsidence lead to the degradation of soil physicochemical and microbial properties, as well as vegetation destruction. While extensive research has been conducted on these issues, investigations concerning the impact of surface cracks and subsidence on soil respiration across different closing stages in mining areas remain scarce. In December 2024 and April 2025, soil respiration was measured using an EMG-5 soil respiration analyzer around surface features at various developmental stages: early-stage non-closed cracks (S1, S2), mid-stage semi-closed cracks (S3), late-stage fully closed cracks (S4), partially self-repaired collapse pits (S5), and non-self-repaired collapse pits (S6). Concurrent observations of soil temperature and moisture were conducted to explore the effects of mining-induced surface cracks and collapse pits on soil respiration. The results indicate that during the early non-closed (S1, S2), mid-stage semi-closed (S3), and non-self-repaired collapse pit (S6) stages, soil respiration exhibited a “V”-shaped pattern. Specifically, respiration values were lowest at the centers of cracks and pits, increasing outwardly toward the sides. The sphere of influence on soil respiration was approximately 50–80 cm from the cracks and 20 cm from the collapse pits, with wider cracks exerting a more extensive influence range. In the late-stage fully closed (S4) and partially self-repaired subsidence (S5) stages, soil respiration displayed a wavy characteristic composed of multiple “V” shapes. No significant difference was observed between soil respiration at the centers of cracks or pits and that at any measured distance, suggesting self-healing characteristics in the study area. Improved self-healing effects corresponded to a smaller sphere of influence, with fully closed surface cracks showing almost no impact on surrounding soil respiration. The influence of soil temperature and moisture on soil respiration around cracks and collapse pits demonstrated distance dependence. Within a 5 cm range, soil moisture was the dominant factor (
P<0.01), whereas outside the 5 cm range, soil temperature prevailed (
P<0.05). Both factors showed a significant negative correlation, acting to inhibit soil respiration during the sampling periods. Consequently, artificial intervention is deemed unnecessary for surface cracks and collapse pits capable of self-repair. Conversely, for wide cracks and deep subsidence pits unable to self-repair, artificial restoration measures—such as soil backfilling and vegetation planting—are required to prevent further ecological deterioration. These findings deepen the understanding of how surface cracks and collapse pits disturb soil respiration processes and provide strategies and recommendations for ecological restoration in mining areas.