Patterns and driving factors of soil nutrient stoichiometry under three land use types in the alpine region of Tibet, China

Purpose Understanding the variations and driving variables of soil ecological stoichiometry in high-altitude alpine ecosystems is crucial for the effective management and regulation of vulnerable environments. In high-altitude alpine ecosystems with limited data availability, the connection between soil nutrient content, particularly soil nutrient stoichiometry and land use types, remains unclear. This study aimed to investigate the characteristics and control of soil nutrient stoichiometric ratios under different land use patterns. Methods A transect covering farmland (FA), forestland (FO), and grassland (GR) was established in the southeast of Tibet Autonomous Region, and totally, 59 sampling points at an interval of 25–30 km were selected for field survey and sampling. The patterns and drivers of soil nutrient stoichiometry under various land use types were studied by measuring soil properties at different depths (0–10 cm, 10–20 cm, and 20–30 cm). Results Soil organic carbon (SOC), total nitrogen (TN), C:N, C:P, and N:P ratios in FO and GR were higher than those in FA, while total phosphorus (TP) exhibited the opposite trend. Both SOC content and C:P ratio were significantly influenced by soil depth ( p < 0.05), showing a declining tendency with the increasing soil depth. TN, TP, C:N, and N:P were not affected by soil depth ( p > 0.05). Redundancy analysis indicated that mean annual rainfall, total porosity, and slope were the key factors affecting soil nutrient stoichiometry in FA and FO, while nutrient stoichiometry in GR was mainly affected by bulk density, altitude, and slope. In the random forest model, soil properties, climate, and topography could jointly explain 60.81⁓84.78% of the total differences in SOC, TN, and TP concentrations and stoichiometric ratios. Conclusion Our findings showed that SOC, TN, and TP concentrations and their ratios were significantly influenced by land use patterns and that the driving factors of SOC, TN, TP concentrations and their stoichiometric ratios were different. This work provides a basis for understanding ecosystem processes and designing sustainable soil and environmental management decisions in alpine regions. Graphical abstract