Xingyu Liu

Coal-dominated resource-based cities face a structurally embedded carbon-neutrality gap, shaped by the simultaneous pressures of industrial carbon lock-in and ecological fragility. China’s dual-carbon targets impose severe transition pressure on such regions, where carbon-intensive industries, strong path dependence, and limited decarbonization flexibility compound the challenge. Forest carbon sinks offer a cost-effective approach for offsetting residual emissions. However, water scarcity and restricted land-carrying capacity impose hard ecological ceilings on sink expansion in semi-arid areas such as the Loess Plateau. Existing studies have largely focused on national or provincial scales, with few addressing the coupled dynamics of industrial emissions and water-limited sink capacity at the county level. This study examines Shenmu, China’s largest coal-producing county-level city and a national energy-chemical industrial base. Using time-series data spanning 2010–2025, we project multi-scenario carbon emissions via an extended STIRPAT model with ridge regression, estimate forest carbon sink potential through a growing-stock (GS) gradient model cross-validated against GM(1,1), and systematically quantify the resulting carbon-neutrality gap. The results show that energy activities dominate total emissions throughout, consistently exceeding 90% of the aggregate. Under the baseline scenario, emissions reach 407.96 MtCO₂eq in 2060 without peaking; under moderate mitigation, emissions peak at 269.39 MtCO₂eq in 2050; under strengthened mitigation, emissions peak at 225.80 MtCO₂eq before 2040 and subsequently decline. Forest carbon sinks are projected to offset 2.1–11.2% of emissions by 2060 under all scenarios, constrained by climatic aridity, finite afforestation potential, and water–soil carrying capacity thresholds. The carbon-neutrality gap remains structurally positive across every scenario, reflecting a fundamental asymmetry between rigid emission growth and ecologically bounded sink capacity. These findings indicate that only an integrated pathway combining industrial restructuring, energy decarbonization, diversified ecological sinks, and CCUS deployment can substantially narrow the gap; carbon neutrality by 2060 is unattainable through natural sinks alone.

A newly discovered facultative anaerobic strain, designated as LXY-3^T, was obtained from a soil sample collected at an industrial site in Guangxi, China, known for heavy metal processing. An investigation including phenotypic, chemotaxonomic, and genomic traits was conducted. Phylogenetic analysis based on 16S rRNA showed that LXY-3^T belonged to the genus Paenibacillus. The closest phylogenetic relative of this strain was Paenibacillus anaericanus MH21^T with the similarity of 97.03%. Iso-C_15:0, antéiso-C_15:0, and C_16:1 ω7c alcohol were the major cellular fatty acids. The predominant polar lipids comprised diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), unidentified phospholipids (PL1-PL8), unidentified resistant material (RM1–RM4), and lipids (L1–L3). For genome sequencing, the genomic DNA G+C content of the strain is 51.2 mol%. Comparative genomic analysis revealed that the average nucleotide identity (ANI) values between strain LXY-3^T and its closest phylogenetic relatives within the genus Paenibacillus (represented by type strains) were consistently below the 95% species demarcation threshold. Nitrogen fixation gene cluster (nifB, nifE, nifK, nifN, nifV, nifX, nifD, and nifH) was conserved in the strain. Correspondingly, digital DNA–DNA hybridization (dDDH) values remained below the 70% cutoff for species delineation. These genomic metrics provide compelling evidence that strain LXY-3^T represents a novel species within the genus Paenibacillus. The type strain LXY-3^T (=CGMCC 1.64949^T = JCM 37600^T) is proposed.

Two bacterial strains, designated LXY-1^T and LXY-4^T, were isolated from soil samples collected at a heavy metal smelting plant located in Guangxi, China. Phylogenetic analysis indicated that these strains formed two distinct lineages within the genus Neobacillus. Both strains were characterized as facultative anaerobic, Gram-positive staining, endospore-forming, non-motile, short-rod bacteria. The major cellular fatty acids identified in these strains included C_16:0, iso-C_15:0, antéiso-C_15:0, and antéiso-C_17:0. The predominant polar lipids comprised diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG). The average nucleotide identity (ANI) values between the newly isolated strains and their closest phylogenetic relatives, the type strains of the genus Neobacillus, were found to be below 95%, with corresponding digital DNA–DNA hybridization (dDDH) values remaining below 70%. Based on a comprehensive polyphasic taxonomic analysis incorporating chemotaxonomic, phenotypic, phylogenetic, and genomic data, we proposed that strains LXY-1^T and LXY-4^T represent two novel species of the genus Neobacillus, for which the names Neobacillus terrisolis sp. nov. and Neobacillus solisequens sp. nov. are designated. The type strains are LXY-1^T (= CGMCC 30313^T = JCM 37671^T) and LXY-4^T (= CGMCC 1.62901^T = JCM 37672^T), respectively.

Engineering construction and mining activities have resulted in numerous exposed rocky slopes, posing significant geological and ecological challenges. To address these issues, this study developed compound microbial agents composed of functional microorganisms and applied them in a field-based ecological restoration project on typical high and steep rocky slopes in Southwest China. The aim was to restore the micro-ecological environment of the slopes by reconstructing the soil conditions. After 240 days of restoration, soil available phosphorus increased from < 2.0 to 6.10 mg/kg, available potassium from 62.80 to 75.00 mg/kg, organic matter from 8.90 to 12.86 g/kg, and organic carbon from 0.70 to 0.73%. Total nitrogen and total phosphorus slightly increased, indicating improved soil fertility. The addition of compound microbial agents enhanced microecological stability while maintaining the overall structure of the indigenous microbial communities. The progressive development of biological soil crusts and rock fissures facilitated the colonization of algae, lichens, mosses, and higher plants. By the 8th month, vegetation coverage exceeded 30% in some areas. This study presents an effective field-based model for the microbial ecological restoration of rocky slopes and offers insights into ecosystem-recovery mechanisms supporting sustainable land management.

To address the ecological restoration needs of steep rocky slopes in southwestern China, this study systematically investigated the mechanisms by which bioremediation technologies influence soil microbial community structure and functional genes involved in carbon and nitrogen cycling. By spraying composite microbial agents (containing functional strains such as Clostridium and Desulfovibrio) and combining Illumina high-throughput sequencing with metagenomic analysis, we evaluated dynamic changes in soil fertility, microbial diversity, and functional genes over a 13 months restoration period. The results showed that total nitrogen (TN), total carbon (TC), and organic matter (OM) contents in the bioremediation area increased by 547.4%, 540.6%, and 1765.7%, respectively, compared to the natural crust group, significantly enhancing the nutrient supply capacity of barren rocky soil. Microbial diversity and richness increased, with functional phyla such as Proteobacteria and Actinobacteriota exhibiting abundance increaseed of 24.5% and 3.4%, respectively, driving synergistic enhancement of carbon, nitrogen, and phosphorus cycling. Metagenomic analysis revealed that carbon fixation genes and nitrogen fixation gene clusters (e.g., nifZ, nifX) were upregulated in the restoration group compared to the control group. This enhancement was achieved by regulating CO2 hydration and biological nitrogen fixation pathways, significantly improving carbon and nitrogen sequestration efficiency in the ecosystem. From a molecular ecology perspective, this study elucidates the mechanism by which microbial remediation facilitates rapid ecological restoration of slopes through reshaping functional microbial networks and activating key metabolic gene expression. These findings provide a theoretical foundation for sustainable restoration of rocky slopes.

Forest carbon sink (FCS) is essential for achieving carbon neutrality and supporting sustainable development in ecologically fragile, resource-based cities such as those on the Loess Plateau. Despite the success of national afforestation programs, economic valuations of FCS at the city level remain limited. This study develops an integrated framework combining carbon stock estimation, regional carbon pricing, and net present value (NPV)-based valuation. Using Shenmu City in Shaanxi Province as a case study, forest carbon stocks from 2010 to 2023 are estimated based on the 2006 IPCC Guidelines. Future stocks (2024–2060) are projected using the GM (1,1) model. A dynamic pricing mechanism with a government-guaranteed floor price is applied under three offset scenarios (5%, 10%, 15%). The results show that Shenmu’s forest carbon stock could reach 20.67 million tonnes of CO₂ by 2060, and under a 15% offset scenario, the peak NPV reaches CNY 4.02 billion. Higher offset ratios increase FCS value by 18–22%, reflecting the growing scarcity of carbon credits. The pricing model improves market stability and investor confidence. This study provides a replicable approach for carbon sink valuation in semi-arid areas and offers policy insights aligned with SDG 13 (Climate Action) and SDG 15 (Life on Land).