【摘要】 土壤碳（C）、氮（N）、磷（P）含量及其化学计量学特征在海拔梯度上具有较大的变化，它们在西藏高海拔地区垂直地带性分布规律尚不清楚。本文在西藏德姆拉山3 600～4 700 m以100 m海拔间隔对表层（0～10 cm）土壤养分和化学计量比进行研究，得到如下结果：（1）土壤SOC在海拔梯度上波动较大，TN和TP波动较小；（2）C/N、C/P主要随土壤SOC含量变化而变化，N/P在4 500 m最高；（3）不同海拔梯度土壤C/N比值总体高于全国均值，C/P和N/P比值总体低于全国均值。这些结果表明影响SOC及N、P变化的主要因素除了与海拔相关的气候条件外，还包括植被类型、土壤质地、地形、人类活动等，从而表现出较高的空间异质性；高原高海拔温度低使得土壤SOC、TN分解慢，分解速率相较全国水平低。研究结果促进了青藏高原山地森林土壤养分供应状况和限制因素的认识，并为德姆拉山森林土壤质量评价等提供数据基础。更多还原

【Abstract】 Soil carbon(C), nitrogen(N), and phosphorus(P) contents, together with their stoichiometric characteristics, exhibit large variations along altitudinal gradients. These variations in high-altitude regions of Xizang are not yet well understood. In this study, we investigated the surface soil(0 ～ 10 cm) chemical properties at altitudinal intervals of 100 m on the Demola Mountain in Xizang, ranging from 3 600 to 4 700 m. The results were as follows:(1) Soil organic carbon(SOC) fluctuated greatly along the altitude gradient, while total nitrogen and phosphorus showed smaller fluctuations;(2) C/N and C/P ratios mainly varied with SOC content, and N/P was the highest at 4 500 m;(3) Soil C/N ratios at different altitudes were generally higher than the national average, while C/P and N/P ratios were generally lower. These results indicated that besides altitude-related climatic conditions, the factors affecting SOC, N, and P variations also included vegetation type, soil texture, topography, and human activities, exihibiting a high degree of spatial heterogeneity. The low temperatures at high altitudes on the plateau slowed down the decomposition of soil SOC and TN, resulting in higher accumulation of SOC than the national average. The results facilitated understanding of the nutrient supply status and limiting factors of mountain forest soils on the Qinghai-Xizang Plateau, and provided useful data for the protection and assessment of forest soil quality on Demola Mountain.更多还原