Improvement of soil quality after land reclamation is a key concern in mining areas. However, the characteristics and internal mechanisms of variation of bacterial community structure over different reclamation periods are currently unclear. The recovery and evolution of soil microbial community structure are important indicators of the level of soil quality improvement of reclaimed soil. Therefore, this study investigated soil samples from coal gangue-filled land after reclamation periods of 1, 6, and 15 years. To accomplish this, 16S rRNA gene libraries were produced to determine the microbial community composition of the soils. In addition, various soil microbial community characteristics in the filled reclamation areas were compared with soil samples from areas unaffected by coal mining. The results showed the following: (1) The diversity and abundance of bacterial communities in reclaimed soils was slightly different from that of natural soils. However, the soil bacterial community structure was highly similar to natural soil after a 15-year reclamation period; therefore, the recovery of bacterial communities can be used as an indicator of the effects of rehabilitation. (2) Some soil physicochemical properties are significantly correlated with the main bacteria in the soil. (3) The dominant bacteria included members of the phyla Firmicutes and Proteobacteria, as well as members of the genera Bacillus, Enterococcus, and Lactococcus. Taken together, the results of this study indicated that the application of microbial remediation technology can be used to adjust the soil microbial community structure, improve soil quality, and shorten the soil recovery period.

We explored the characteristics of soil bacterial communities and their ecological functions under different types of vegetation reclamation in open-pit mines on the Loess Plateau, which is the guiding significance for the selection of vegetation and the improvement of restoration effect in mining areas. The research object was to reclaim the soil of the aluminum mine waste dump in Xiaoyi County, Shanxi. The soil characteristics were measured under different types of vegetation reclamation. The soil bacterial community under different vegetation reclamation was measured using the 16S rRNA gene high-throughput sequencing technology. The ecological function was predicted using the PICRUSt method. The correlation between soil physical and chemical properties and bacterial community structure and function was analyzed. From the results, (1) the bacterial compositions of the reclaimed soil samples were 33 phyla, 90 classes, 121 orders, 207 families, 298 genera, and 140 species. The abundance and diversity of the soil microbial community showed the rule of yellow rose > lespedeza and sweet wormwood herb > alfalfa. (2) Proteobacteria were the dominant bacteria in alfalfa and sweet wormwood herb samples, accounting for 36.09–43.36%. Proteobacteria and actinobacteria were the dominant bacteria in the yellow rose and lespedeza samples accounted for 53.34–53.39%. α-Proteobacteria, actinobacteria, and β-proteobacteria were the dominant bacteria of the four vegetation types. The relative abundance of the α-proteobacteria and β-proteobacteria was positively correlated with soil organic carbon (SOC) and negatively correlated with soil total kalium (TK). Actinobacteria were positively correlated with available kalium (AK) and negatively correlated with SOC and total nitrogen (TN). (3) There was no difference in the primary functions of the soil bacterial community after the reclamation of different plants, and the main functions were metabolism, genetic information processing, and environmental information processing, with the function abundance accounting for 81.52%. (4) The abundance of functional genes in the metabolism of other amino acids, folding, sorting, and degradation and glycan biosynthesis and metabolism were relatively rich in the rhizosphere soil of yellow rose. The abundance of functional genes in signal molecules and interaction, transport, and catabolism in the rhizosphere soil of lespedeza was the highest. The abundance of functional genes in carbohydrate metabolism, translation, and energy metabolism in the rhizosphere soil of alfalfa was the highest. Therefore, there were significant differences in the structure and function of rhizosphere soil microbial communities among yellow rose, lespedeza, sweet wormwood herb, and alfalfa, and they were also affected by the soil properties. Hence, we concluded that the differences and diversity of soil microbial structure and function can help select plants for the sustainable development of soil remediation in mining areas.

To compare the effects of different remediation tree species on soil bacterial communities and provide a theoretical basis for the selection of ecosystem function promotion strategies after vegetation restoration, the characteristic changes in soil bacterial communities after Pinus tabulaeformis and Populus euramericana reclamation were explored using high-throughput sequencing and molecular ecological network methods. The results showed that: (1) With the increase in reclamation years, the reclaimed soil properties were close to the control group, and the soil properties of Pinus tabulaeformis were closer to the control group than those of P. euramericana. (2) The dominant bacteria under the canopies of P. tabulaeformis and P. euramericana was the same. Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, Gemmatimonadetes, Planctomycetes, Bacteroidetes, and Cyanobacteria were the dominant bacteria in the restored soil, accounting for more than 95% of the total abundance. The average values of the Shannon diversity index, Simpson diversity index, Chao 1 richness estimator, and abundance-based coverage estimator of the bacterial community in the P. euramericana reclaimed soil were higher than those in the P. tabulaeformis reclaimed soil. The influence of reclamation years on the bacterial community of samples is greater than that of species types. (3) The results of ecological network construction showed that the total number of nodes, total number of connections, and average connectivity of the soil bacterial network under P. euramericana reclamation were greater than those under P. tabulaeformis reclamation. The bacterial molecular ecological network under P. euramericana was more abundant. (4) Among the dominant bacteria, the relative abundance of Actinobacteria was negatively correlated with soil pH, soil total nitrogen content, and the activities of urease, invertase, and alkaline phosphatase, while the relative abundance of Proteobacteria and Bacteroidetes was positively correlated with these environmental factors. The relationship between the soil bacterial community of P. tabulaeformis and P. euramericana and the environmental factors is not completely the same, and even the interaction between some environmental factors and bacteria is opposite.

Surface mining activities cause severe disruption to ecosystems, resulting in the substantial destruction of surface vegetation, the loss of soil organic carbon stocks, and a decrease in the ecosystem’s ability to sequester carbon. The ecological restoration of mining areas has been found to significantly enhance the carbon storage capacity of ecosystems. This study evaluated ecological restoration strategies in Chongqing’s Tongluo Mountain mining area by integrating GF-6 satellite multispectral data (2 m panchromatic/8 m multispectral resolution) with ground surveys across 45 quadrats to develop a quadratic regression model based on vegetation indices and the field-measured biomass. The methodology quantified carbon storage variations among engineered restoration (ER), natural recovery (NR), and unmanaged sites (CWR) while identifying optimal vegetation configurations for karst ecosystems. The methodology combined the high-spatial-resolution satellite imagery for large-scale vegetation mapping with field-measured biomass calibration to enhance the quantitative accuracy, enabling an efficient carbon storage assessment across heterogeneous landscapes. This hybrid approach overcame the limitations of traditional plot-based methods by providing spatially explicit, cost-effective monitoring solutions for mining ecosystems. The results demonstrate that engineered restoration significantly enhances carbon sequestration, with the aboveground vegetation biomass reaching 5.07 ± 1.05 tC/ha, a value 21% higher than in natural recovery areas (4.18 ± 0.23 tC/ha) and 189% greater than at unmanaged sites (1.75 ± 1.03 tC/ha). In areas subjected to engineered restoration, both the vegetation and soil carbon storage showed an upward trend, with soil carbon sequestration being the primary form, contributing to 81% of the total carbon storage, and with engineered restoration areas exceeding natural recovery and unmanaged zones by 17.6% and 106%, respectively, in terms of their soil carbon density (40.41 ± 9.99 tC/ha). Significant variations in the carbon sequestration capacity were observed across vegetation types. Bamboo forests exhibited the highest carbon density (25.8 tC/ha), followed by tree forests (2.54 ± 0.53 tC/ha), while grasslands showed the lowest values (0.88 ± 0.52 tC/ha). For future restoration initiatives, it is advisable to select suitable vegetation types based on the local dominant species for a comprehensive approach.

Enhanced rock weathering is regarded as a promising carbon dioxide removal method because of its potential to sequester soil inorganic carbon (SIC). However, the influence of enhanced rock weathering on changes in soil organic carbon (SOC) content, fractions and stability remains poorly understood. A randomized block experiment design employing five basalt addition rates (0 (CK), 2.5, 5, 10 and 20 kg·m⁻²) and four replicates was designed to investigate the influences of basalt addition on SOC and SIC content and stocks, SOC fractions and SOC stability in subtropical cropland, where Zea mays L. and Brassica juncea (L.) Czern were annually rotated. Soil samples were collected from depths of 0–15 cm and 15–30 cm one year after the addition of basalt. The results showed that enhanced rock weathering increased the total carbon content and stock by increasing both the SOC and SIC in a one-year field experiment. Compared with CK, basalt addition rates of 2.5, 5, 10 and 20 kg·m⁻² increased the SOC stock by 16%, 23%, 21% and 19%, respectively, and the SIC stock by 37%, 30%, 35% and 32%, respectively. The labile carbon fraction was the primary organic carbon fraction, which accounted for more than 40% of the total SOC content. Enhanced rock weathering altered the content of the very labile carbon fraction due to its high sensitivity to basalt addition, but had little effect on the stable carbon fraction content in a one-year field experiment. Compared with CK, basalt addition increased the very labile carbon fraction content by 12% and 46%, respectively, according to samples from depths of 0–15 cm and 15–30 cm. Under basalt addition rates of 2.5, 5, 10 and 20 kg·m⁻², the SOC stability index was 26%, 21%, 17% and 20%, respectively, lower than that under the 0-addition rate in a one-year field experiment, which was 1.63, indicating that enhanced rock weathering reduced the SOC stability. Our findings indicated that enhanced rock weathering increased soil carbon (both of SOC and SIC) sequestration, but reduced the SOC stability in a one-year field experiment in subtropical croplands. These observed trends in changes in soil carbon will be further tested and evaluated as the experiment continues in the future.