Li Chunjie, Guo Shili, Shang Songhao
School of Geographic Science and Tourism, Nanyang Normal University, Wolong Road No.1638, Nanyang, China.
Key Laboratory of Natural Disaster and Remote Sensing of Henan Province, Nanyang Normal University, Nanyang, China.
PLoS One. 2025 Jun 2;20(6):e0325425. doi: 10.1371/journal.pone.0325425. eCollection 2025.
The altitudinal gradient in mountainous areas triggers significant changes in landscape, climate, and vegetation, which in turn affect the vertical differentiation of soil type and their properties. Located in the transitional zone between the northern and southern climates of East Asia, Tongbai Mountain is of great geographical and ecological significance and is highly sensitive to global changes. However, systematic research on soil biogeochemical processes in the vertical zonation of mountainous areas in this transitional zone is still lacking. In this study, a sampling strategy based on altitude gradients was used, combined with a variety of advanced analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and Fourier transform infrared spectroscopy (FTIR), to comprehensively characterize the mineral composition, soil organic carbon (SOC), and heavy metal element distribution of soils at different altitudes in Mount Tongbai. The results showed that the mineral composition of the soil exhibited a clear gradient based on altitude. The Quartz content was higher at low and high altitudes, while the feldspar mineral content was highest in the middle altitudes. Illite increased with increasing altitude. SOC content increased significantly with increasing altitude, and hydroxyl, amino and aliphatic organic matter were enriched in high altitudes. Heavy metal elements such as Fe, Ti, Cu, and Zn increased in high altitudes, and the microstructure of soil aggregates in high altitudes was more complex and stable. Through a comprehensive analysis, MgO, Zr, 2929 cm⁻¹, 3423 cm⁻¹, and Cu were selected as sensitive biogeochemical factors in the vertical band spectrum. This study reveals for the first time the mechanism behind the coordinated evolution of soil minerals, SOC, and heavy metal elements driven by the altitude gradient. This deepens our understanding of biogeochemical processes in the vertical band spectrum of mountains in the climatic transition zone between North and South East Asia, and provides a scientific basis to formulate management strategies for mountain ecosystems in the climatic transition zone.
山区的海拔梯度引发了景观、气候和植被的显著变化，进而影响土壤类型及其性质的垂直分异。桐柏山位于东亚南北气候的过渡地带，具有重要的地理和生态意义，对全球变化高度敏感。然而，目前仍缺乏对该过渡带山区垂直地带性土壤生物地球化学过程的系统研究。本研究采用基于海拔梯度的采样策略，结合扫描电子显微镜（SEM）、X射线衍射（XRD）、X射线荧光光谱（XRF）和傅里叶变换红外光谱（FTIR）等多种先进分析技术，全面表征桐柏山不同海拔土壤的矿物组成、土壤有机碳（SOC）和重金属元素分布。结果表明，土壤矿物组成随海拔呈现明显梯度。石英含量在低海拔和高海拔较高，而长石矿物含量在中海拔最高。伊利石随海拔升高而增加。SOC含量随海拔升高显著增加，高海拔地区富含羟基、氨基和脂肪族有机质。Fe、Ti、Cu和Zn等重金属元素在高海拔地区增加，高海拔地区土壤团聚体的微观结构更复杂且稳定。通过综合分析，选择MgO、Zr、2929 cm⁻¹、3423 cm⁻¹和Cu作为垂直带谱中敏感的生物地球化学因子。本研究首次揭示了海拔梯度驱动下土壤矿物、SOC和重金属元素协同演化的机制。这加深了我们对东亚南北气候过渡带山区垂直带谱中生物地球化学过程的理解，并为制定气候过渡带山区生态系统管理策略提供了科学依据。
