Soil erosion-prone areas require effective microbial treatments to improve soil bacterial communities and functional traits. Understanding the driving effects of different microbial interventions on soil ecology is essential for restoration efforts. Single and combined microbial treatments were applied to soil. Bacterial community structure was analyzed via 16S IRNA high-throughput sequencing, and functional groups were predicted using FAPROTAX. Soil microbial carbon, nitrogen, metabolic entropy, and enzymatic activity were assessed. Microbial Carbon and Metabolic Activity: The Arbuscular mycorrhizal fungi (AMF) and Bacillus mucilaginosus (BM) (AMF.BM) treatment exhibited the highest microbial carbon content and the lowest metabolic entropy. The microbial carbon-to-nitrogen ratio ranged from 1.27 to 3.69 across all treatments. Bacterial Community Composition: The dominant bacterial phyla included Firmicutes, Proteobacteria, Acidobacteria, Bacteroidetes, and Actinobacteria. Diversity and Richness: The AMF and Trichoderma harzianum (TH) (AMF.TH) treatment significantly reduced diversity, richness, and phylogenetic diversity indices, while the AMF.BM treatment showed a significantly higher richness index (p < 0.05). Relative Abundance of Firmicutes: Compared to the control, the AMF, TH.BM, and TH treatments decreased the relative abundance of Firmicutes, whereas the AMF.TH treatment increased their relative abundance. Environmental Correlations: Redundancy and correlation analyses revealed significant correlations between soil organic matter, magnesium content, and sucrase activity and several major bacterial genera. Functional Prediction: The AMF.BM treatment enhanced the relative abundance and evenness of bacterial ecological functions, primarily driving nitrification, aerobic ammonia oxidation, and ureolysis. Microbial treatments differentially influence soil bacterial communities and functions. The AMF.BM combination shows the greatest potential for ecological restoration in erosion-prone soils.

Restoring soil microbial functioning in reclaimed coal gangue soils is critical for ecosystem recovery, yet how different organic amendments, particularly industrial by-products, regulate bacterial communities remains unclear. Here, we tested three organic inputs—the residue after evaporation (RAE) from vitamin C production, Trichoderma inoculation, and cattle manure—applied alone and in combination in a photovoltaic agroforestry system on coal gangue spoil. Our results indicate that the treatment based on manure increased bacterial α-diversity and favored taxa associated with organic matter transformation, including Actinobacteria and Acidobacteriota, suggesting expanded niche partitioning in response to heterogeneous substrates and nutrients. RAE alone supported communities closer to non-manure controls but, when co-applied with manure, further enhanced network connectivity and the prevalence of positive associations, indicating strengthened cooperative interactions and functional redundancy. In contrast, RAE combined with Trichoderma in the absence of manure reduced diversity, and simplified the co-occurrence network, suggesting resource monopolization and antagonism. Overall, RAE acted as a key driver of microbial cooperation and potential ecosystem resilience, and RAE-based amendments, particularly when integrated with manure, appear to be effective strategies for improving soil microbial functionality in degraded coal gangue soils.

The decline of Mongolian Scots pine (Pinus sylvestris var. mongolica) plantations in the “Three-North” shelterbelt region is closely linked to soil degradation. This study compared rhizosphere and non-rhizosphere soils across different stand ages, focusing on nutrient availability, microbial biomass, enzyme activities, and soil particle morphology. Results showed that SOC and TN accumulated with age, whereas AP, AK, and pH declined in older stands, indicating progressive acidification. Results demonstrated that SOC and TN increased with stand age, whereas AP, AK, and pH exhibited a marked decline in the older stands (stands aged ≥ 40 years), reflecting progressive acidification and nutrient depletion. Rhizosphere soils consistently displayed higher SOC, TN, microbial biomass, and enzyme activities than non-rhizosphere soils, largely driven by root exudation and enhanced microbial turnover. The increasing C_mic/N_mic ratio with age suggested a fungal-dominated microbial community, which may exacerbate stand decline by fostering pathogenic fungi. Scanning electron microscopy revealed pronounced particle fragmentation and surface roughness with increasing stand age, particularly in rhizosphere soils, indicating root-driven physical and biochemical weathering. These findings highlight the synergistic effects of stand development and rhizosphere processes on soil structure and fertility, providing a theoretical basis for the sustainable management and restoration of declining plantations.