School of Geographical Sciences, Qinghai Normal University, Xining, 810008, Qinghai, China.
Qinghai Provincial Key Laboratory of Physical Geography and Environmental Processes, Qinghai Normal University, Xining, 810008, Qinghai, China.
Environ Monit Assess. 2023 May 25;195(6):724. doi: 10.1007/s10661-023-11251-4.
Soil carbon and nitrogen levels are key indicators of soil fertility and are used to assess ecological value and safeguard the environment. Previous studies have focused on the contributions of vegetation, topography, physical and chemical qualities, and meteorology to soil carbon and nitrogen change, but there has been little consideration of landscape and ecological environment types as potential driving forces. The study investigated the horizontal and vertical distribution and influencing factors of total carbon and total nitrogen in soil at 0-20 and 20-50 cm depths in the source region of the Heihe River. A total of 16 influencing factors related to soil, vegetation, landscape, and ecological environment were selected, and their individual and synergistic effects on the distributions of total carbon and total nitrogen in soil were assessed. The results show gradually decreasing average values of soil total carbon and total nitrogen from the surface layer to the bottom layer, with larger values in the southeast part of the sampling region and smaller values in the northwest. Larger values of soil total carbon and total nitrogen at sampling points are distributed in areas with higher clay and silt and lower soil bulk density, pH, and sand. For environmental factors, larger values of soil total carbon and total nitrogen are distributed in areas with higher annual rainfall, net primary productivity, vegetation index, and urban building index, and lower surface moisture, maximum patch index, boundary density, and bare soil index. Among soil factors, soil bulk density and silt are most closely associated with soil total carbon and total nitrogen. Among surface factors, vegetation index, soil erosion, and urban building index have the greatest influence on vertical distribution, and maximum patch index, surface moisture, and net primary productivity have the greatest influence on horizontal distribution. In conclusion, vegetation, landscape, and soil physical properties all have a significant impact on the distribution of soil carbon and nitrogen, suggesting better strategies to improve soil fertility.
土壤碳氮水平是土壤肥力的关键指标，用于评估生态价值和保护环境。先前的研究集中于植被、地形、物理和化学性质以及气象对土壤碳氮变化的贡献，但很少考虑景观和生态环境类型作为潜在驱动力。本研究调查了黑河源头地区土壤在 0-20cm 和 20-50cm 深度的总碳和总氮的水平和垂直分布及其影响因素。共选取了 16 个与土壤、植被、景观和生态环境有关的影响因素，评估了它们对土壤总碳和总氮分布的单独和协同作用。结果表明，土壤总碳和总氮从表层到底层逐渐减少，采样区东南部值较大，西北部值较小。土壤总碳和总氮值较大的采样点分布在粘土和粉土含量较高、土壤容重、pH 值和沙含量较低的地区。对于环境因素，土壤总碳和总氮值较大的地区分布在年降雨量、净初级生产力、植被指数和城市建筑指数较高、地表湿度、最大斑块指数、边界密度和裸土指数较低的地区。在土壤因素中，土壤容重和粉土与土壤总碳和总氮关系最密切。在地表因素中，植被指数、土壤侵蚀和城市建筑指数对垂直分布的影响最大，最大斑块指数、地表湿度和净初级生产力对水平分布的影响最大。总之，植被、景观和土壤物理性质对土壤碳氮的分布有显著影响，这表明改善土壤肥力的策略需要更好地考虑这些因素。
