Response of soil quality to ecosystems after revegetation in a coal mine reclamation area

Revegetation is widely acknowledged as a vital strategy for the ecological restoration of coal mine reclamation areas. However, the mechanisms governing the internal regulation of ecosystems through vegetation succession over extended reclamation periods remain poorly understood. To address this gap, this study investigated the regulatory roles of ecosystem structure and functional factors in mining areas after vegetation reconstruction, as well as their dynamic effects on soil quality. This study specifically focused on the ecosystems of artificial Hippophae rhamnoides forests in the Ordos Mining Area of Inner Mongolia during different restoration periods. This study aimed to elucidate these dynamics by analysing soil quality, network structure, and ecosystem function in H. rhamnoides forests across different reclamation durations. Preliminary findings revealed the following: (1) the minimum data set for assessing soil quality in H. rhamnoides forest land within coal mine reclamation areas included sand, the bacterial Chao1 index, the fungal Shannon index, total phosphorus (TP), total soil porosity (TCP), soil organic matter (OM), available phosphorus (AP), and capillary water-holding capacity (CWHC), among which soil OM and the bacterial Chao1 index were identified as the key indicators for evaluating soil quality. Furthermore, the soil quality index of the H. rhamnoides forest improved with increasing reclamation duration. (2) As the number of reclamation years increased, the ecosystem network became more interconnected and structurally stable. The number of links within the network structure peaked in the seventh year after reclamation. Revegetation altered the hubs of the ecosystem network, with soil grain size and water-holding capacity emerging as significant hubs. Over time, biomass and herbaceous diversity gradually became crucial factors in ecosystems. (3) Soil quality in the H. rhamnoides forest was influenced by various ecological functional factors, as demonstrated by structural equation modelling. Soil OM, AP, and understory herbaceous diversity were identified as the primary factors affecting soil quality.