Vegetation dynamics and their responses to climate change are of significant spatial and temporal heterogeneity. The Sichuan–Tibet Railway (STR) is a major construction project of the 14th Five-Year Plan for Economic and Social Development of the People’s Republic of China that is of great significance to promoting the social and economic development of Sichuan–Tibet areas. The planned railway line crosses areas with a complex geological condition and fragile ecological environment, where the regional vegetation dynamics are sensitive to climate change, topographic conditions and human activities. So, analyzing the vegetation variations in the complex vertical ecosystem and exploring their responses to hydrothermal factors are critical for providing technical support for the ecological program’s implementation along the route of the planned railway line. Based on MOD13Q1 Normalized Difference Vegetation Index (NDVI) data for the growing season (May to October) during 2001–2020, a Theil-Sen trend analysis, Mann–Kendall test, Hurst exponent analysis and partial correlation analysis were used to detect the vegetation dynamics, predict the vegetation sustainability, examine the relationship between vegetation change and hydrothermal factors, regionalize the driving forces for vegetation growth and explore the interannual variation pattern of driving factors. The growing season NDVI along the Ya’an–Linzhi section of the STR showed a marked rate of increase (0.0009/year) during the past 20 years, and the vegetation’s slight improvement areas accounted for the largest proportion (47.53%). Among the three hydrothermal parameters (temperature, precipitation and radiation), the correlation between vegetation growth and the temperature was the most significant, and the vegetation response to precipitation was the most immediate. The vegetation changes were affected by the combined impact of climatic and non-climatic factors, and the proportion of hydrothermal factors’ combined driving force slightly increased during the study period. Based on the Hurst exponent, the future vegetation sustainability of the area along the Ya’an–Linzhi section of the STR faces a risk of degradation, and more effective conservations should be implemented during the railway construction period to protect the regional ecological environment.

Dual isotopes of sulfate (δ³⁴SSO₄ and δ¹⁸OSO₄), along with isotopes in water and trace elements of geothermal waters, are systematically investigated to quantitatively elucidate sulfate sources and oxygen and sulfur isotopic behaviors during deep groundwater circulation and to constrain reservoir temperatures in the Jimo nonvolcanic geothermal system on the eastern coast of China. The results show that δ³⁴SSO₄ and δ¹⁸OSO₄ values in geothermal waters ranged from −21.0 to 5.7‰ and from 1.1 to 8.8‰, respectively. An increase in SO₄ concentrations (140–796 mg/L) with a systematic decrease in δ³⁴SSO₄ and δ¹⁸OSO₄ values was observed along the flow path from the central to eastern and western parts. The sulfate in the Middle Group was predominantly from atmospheric deposition, with sulfide oxidation contributions of <27%. In contrast, 80–85% of SO₄ in the Eastern Group is derived from pyrite oxidation. In the Western Group, the oxidation of multiple metal sulfides contributed 43–66% of SO₄. Sulfate oxidation and mixing of shallow groundwater caused reservoir temperatures to be underestimated by 9 ± 6–14 ± 16% using silica and K-Mg geothermometers but overestimated by up to 52–62% using sulfate–water oxygen isotope geothermometers. The estimated average target reservoir temperature was 144 ± 8 °C, with geothermal waters circulating to depths of 3.6–4.6 km. This study offers new insights into the significant impact of sulfate-related processes on geothermometric estimates, a factor often overlooked when using aqueous geothermometers. It also provides valuable guidance for accurately estimating target geothermal reservoir temperatures and advancing exploration in nonvolcanic geothermal systems.

The granite rubble soil produced through excavation during construction is nutrient-poor and has a simplified microbial community, making it difficult for plants to grow and increasing the challenges of ecological restoration. Recent studies have demonstrated that microbial inoculants significantly promote plant growth and are considered a potential factor influencing root development. Microorganisms influence root development either directly or indirectly, forming beneficial symbiotic relationships with plant roots. However, the mechanisms by which microorganisms affect root development and root anatomy, as well as the dynamics of soil microbial communities following the artificial application of microbial inoculants, remain unclear. This experiment utilized granite rubble soil from construction excavation in a pot trial, implementing five different treatment methods. After the fast-growing grass species tall fescue (Festuca arundinacea) was planted, four growth-promoting microbial inoculants—Bacillus subtilis (K), Bacillus amyloliquefaciens (JD), Aspergillus niger (H), and Trichoderma harzianum (HC)—were applied to the soil in the pots. These treatments were compared with a control group (CK) that received no microbial inoculant. At 120 days of plant growth, the composition of the soil microbial community, biomass, root structure, and root anatomy were measured for each treatment group. This analysis aimed to explore the effects of different microbial treatments on the microbial communities and root development of Festuca arundinacea root soil. The study found that the addition of microbial inoculants reduced the number of microbial operational taxonomic units (OTUs) of bacteria and fungi in the soil, affecting both the marker species and their abundance at the phylum level. Additionally, microbial inoculants promoted the development of the tall fescue root structure, increasing metrics such as the total root length, root surface area, root volume, and root-to-shoot ratio per plant. Redundancy analysis (RDA) revealed that the area ratios of various components in the root anatomy of tall fescue’s primary roots, such as the root cortex area, stele area, and the number of lateral roots, were influenced by Proteobacteria. Mortierellomycota was found to affect the root epidermis area.

The rapid expansion of tunnel engineering in China has led to extensive excavation of gravelly soils, resulting in significant land occupation that threatens the ecological environment and surrounding biota. As a result, there is an increasing need for effective ecological restoration of nutrient-poor gravelly soils, where challenges in vegetation establishment and sustainable soil management persist. This study evaluates the potential of Bacillus subtilis to promote the growth of Festuca arundinacea in engineered gravel soils through a controlled greenhouse experiment, examining its effects on plant growth, soil nutrient dynamics, and microbial community structure. The results showed that, compared to the control group (CK), neither the Bacillus subtilis treatment group (Bs) nor the nutrient application treatment group (LB) significantly altered the soil bacterial species composition at the phylum level. However, at the genus level, Azotobacter dominated the LB group, while Sphingomonas was the predominant genus in both the CK and Bs groups. Additionally, Bacillus subtilis significantly increased bacterial diversity relative to the nutrient application treatment, leading to substantial changes in microbial community composition. Furthermore, Bacillus subtilis notably enhanced both aboveground and belowground biomass, improved nutrient uptake, and increased the availability of phosphorus and potassium. It also stimulated soil enzymatic activities involved in carbon, nitrogen, and phosphorus cycling, emphasizing its critical role in nutrient cycling. Thus, Bacillus subtilis–driven soil enhancement offers a promising solution for ecological restoration in nutrient-poor gravelly soils, where conventional amendments are often ineffective. These findings underscore the potential of microbial-plant synergies to improve soil fertility and support sustainable vegetation restoration.

《地球科学》(ISSN 1000-2383;CN42-1874/P) (原刊名《地球科学——中国地质大学学报》ISSN 1000-2383;CN42-1233/P)，创刊于1957年，是由教育部主管、中国地质大学主办的综合性地学学术理论期刊，月刊，2015年改名为《地球科学》,她以反映中国地质大学教学与科研最新的、高水平的基础地质、应用地质、资源与环境地质及地学工程技术研究成果为主要任务。