三江源土壤养分分布特征及其对主要气候要素的响应

Distribution of Soil Nutrients and Response to Main Climatic Factors in Three River Source

选择三江源地区22 个高寒草甸样地进行土壤分层（0-10,10-20,20-30 cm）取样,测定土壤的pH 值、有机碳（Totalorganic carbon,TOC）、全氮（Total nitrogen,TN）、速效氮（Available N）、全磷（Total phosphorus,TP）和速效磷（AvailableP,AP）,并与年均温（Mean annual temperature,MAT）和年降水量（Mean annual precipitation,MAP）进行相关分析.结果表明：在研究区域,从西北向东南pH 值依次降低,而土壤养分中的有机碳、全氮和速效氮的分布特征则相反.随着土壤深度的增加,pH 值先保持不变后稍微增大,土壤各养分含量呈减少趋势,其中10-20 和20-30 cm 土壤中的全氮含量分别为3.85,3.40 g·kg^-1,速效磷含量分别为3.67 和3.90 mg·kg^-1,即全氮和速效磷含量在深层土壤中变化幅度不大.在对温度降水响应方面,有机碳、全氮和全磷,对年降水量比年平均温度更敏感,呈现显著的正相关关系;土壤pH 值与年降水量呈显著的负相关关系;土壤pH 值和大部分养分在浅层土壤比深层土壤对温度降水的灵敏度大,然而速效磷与年均温的负相关关系在20-30 cm（-0.617,P〈0.01）土壤中大于0-10 cm（-0.509,P〈0.05）、10-20 cm（-0.521,P〈0.05）土壤.

Twenty-two sites in alpine meadow were chosen to determined the spatial pattern of the soil pH, total organic C (TOC), total N (TN), total P (TP), available N (AN)and available P (AP), Three River Source. We explored the correlation relationships between soil nutrient content and mean annual temperature (MAT), mean annual precipitation (MAP). The results indicated that the pH decreased gradually, but the characteristic of distribution of TOC, TN and AN was increased from northwest to southeast. pH was increased slightly with the increased of soil depth. However, the content of soil nutrients was decreased. In the soil depths of 10~20 cm and 20~30 cm, the content of TN was 3.85 g·kg-1, 3.40 g·kg-1 and the content of AP was 3.67 mg·kg-1, 3.90 mg·kg-1 respectively. In terms of the response to MAT and MAP, the TOC, AN, AP were more sensitive to MAP than MAT which have a significant positive correlation; on the other hand, the pH has a significant negative correlation with MAP. Besides, the sensitivity of pH and mostly soil nutrients to MAT and MAP was higher in shallow soil than the deeper soil depths, but the negative relationship between AP and MAT was higher in 20~30 cm (-0.617,P<0.01) than that in 0~10 cm (-0.509,P<0.05) and 10~20cm (-0.521,P<0.05) soil depth.