关键词: 秦岭北麓, 不同植被类型, 土壤有机碳含量, 空间分布, 环境因子

Abstract: Aims Exploring the high-precision distribution and influencing factors of soil organic carbon (SOC) content under different vegetation types in the northern foot of the Qinling Mountains, that of great significance for accurately assessing the region's soil carbon pool and evaluating its ecosystem service functions. Methods Taking the typical vegetation types of broadleaf forest, coniferous forest, shrubland, grassland, and cropland in the ecological protection area of the northern foot of the Qinling Mountains as the research objects, this study evaluated the distribution patterns of SOC in the 0–100 cm soil profile across these five vegetation types based on a large amount of SOC data obtained from 431 sample points using the Kriging interpolation method. Additionally, path analysis was employed to investigate the main influencing factors of SOC pools in these five vegetation types. Important findings In the northern foot of the Qinling Mountains, the SOC content in the surface layer (0–10 cm) reaches its peak. Among the vegetation types, broadleaf forest has the highest average organic carbon content of 19.45 g/kg, while shrubland has the lowest average organic carbon content of 14.50 g/kg, which is approximately 74.6% of that in broadleaf forests. Across the entire 0–100 cm soil profile, the SOC content ranges for the five vegetation types—broadleaf forest, coniferous forest, shrubland, grassland, and cropland—are 2.60–37.27 g/kg, 3.02–14.01 g/kg, 4.41–13.38 g/kg, 4.00–10.83 g/kg, and 3.05–14.31 g/kg, respectively. The average SOC contents are 7.32 g/kg, 6.44 g/kg, 6.95 g/kg, 6.03 g/kg, and 5.90 g/kg, respectively. Cropland has the lowest average SOC content, which is approximately 80.6% of that in broadleaf forests. The influence of various factors on SOC content varied among vegetation types. Terrain features (elevation, slope, aspect), vegetation cover (NDVI), climatic conditions (mean annual temperature and precipitation), soil physicochemical properties (pH, total nitrogen, total phosphorus, total potassium), and soil texture (sand, silt, and clay content) collectively explained 25%, 30%, 38%, 59%, and 16% of the spatial variability in SOC content for broadleaf forest, coniferous forest, shrubland, grassland, and cropland, respectively. Climatic factors and soil physicochemical properties exerted the greatest influence, with mean annual temperature and total nitrogen being the primary affecting factors.

Key words: the northern foot of Qinling Mountains, different vegetation types, soil organic carbon content, spatial distribution, environmental factors