古尔班通古特沙漠西南缘柽柳沙包的土壤化学计量特征

柽柳沙包作为沙漠地区一种特殊的生物地貌景观,在维持区域生态环境稳定中发挥着极为重要的作用。以古尔班通古特沙漠西南缘的典型柽柳沙包为研究对象,通过对土壤含水量、pH值、电导率、粒径及土壤有机碳（SOC）、总氮（TN）、总磷（TP）含量的分析,探讨了古尔班通古特沙漠柽柳沙包中土壤C、N、P的化学计量特征、垂直变化规律及影响因素。结果表明：（1）随着土层深度增加,SOC和TN均呈先升高后降低的变化,且C、N在表层土壤含量最高,具有"肥岛效应";总磷（TP）含量总体变化幅度较小,呈弱变异。随着土层深度增加,土壤C/N呈先降低后升高再降低的变化,C/P和N/P呈先降低后升高的变化。（2）与全球及中国平均值相比,古尔班通古特沙漠柽柳沙包土壤C、N、P、C/N、C/P及N/P均相对较低,而C/N相对较高,土壤养分缺乏程度表现为N > C > P。土壤养分元素及化学计量比多呈显著的线性关系,且土壤化学计量比在0-200 cm层主要受C、N的制约,在200-500 cm层不仅受C、N的制约,也受P的限制。（3）土壤C、N、P化学计量特征在0-200 cm层主要受降水、温度及蒸发等气候因素的影响,而在200-500 cm层易受土壤含水量的影响;此外,粘、粉、沙粒含量在整个土壤剖面中对土壤C、N、P化学计量特征也具有明显的影响。

Soil stoichiometric characteristics of Tamarix cones in the southwest margin of Gurbantunggut Desert

Tamarix cones, as one of special bio-geographical phenomena, play a crucial role in maintaining the stability of desert environments. The main objectives of this study were to explore soil carbon (C), nitrogen (N), and phosphorus (P) stoichiometric features, and to clarify the relationships between soil C, N, P stoichiometry and environmental factors in the southwest of Gurbantunggut Desert. Soil samples were collected in the Tamarix cones for analyzing soil physico-chemical properties including pH, electrical conductivity (EC), water content, grain composition, organic carbon (OC), total nitrogen (TN) and total phosphorus (TP) content. The results showed that (1) with the increase of soil depth, the SOC and TN decreased firstly and then increased, and soil C and N were the highest in the surface layer, showing "fertile island effect"; and TP was weakly fluctuated along the soil profiles. With the increase of soil depth, C/N decreased firstly and then increased, and decreased again. C/P and N/P decreased firstly and then increased. (2) Compared with the global soils and the averages of China, soil C, N, P, C/P and N/P in the Tamarix cones were relatively lower, but C/N was relatively higher. The degree of deficiency of soil nutrient elements were ranked in order N > C > P. The soil nutrients and their stoichiometric ratios exhibited a significantly linear relationships with other nutrients, and the stoichiometric ratios were dominated by C and N in surface layers (0-200 cm), while in deep layers (200-500 cm) they were limited not only C and N, but also P. (3) In the soil layers of 0-200 cm, soil nutrients and its stoichiometry were susceptible to climatic factors such as precipitation, temperature and evaporation. However, in the soil layers of 200-500cm, soil nutrient and its stoichiometriy was influenced by soil water content.. Soil clay, silt and sand also had significant effects on soil C, N, P and their stoichiometric ratios throughout the soil profiles.