贺兰山西坡不同海拔梯度草地土壤磷特征及其影响因素

对贺兰山西坡不同海拔的不同类型草地土壤磷素的空间分布特征以及环境及植被因素对土壤磷素的影响进行了研究。结果表明，0-10和10-20 cm土层土壤全磷(TP)含量随着海拔由高到低而显著降低；两土层中，土壤全磷与土壤有机碳、土壤中0.05 mm粘粉粒含量及植被盖度之间呈显著正相关(P＜0.05)，土壤全磷沿土壤剖面的垂直分布没有一致规律性；土壤速效磷含量随着海拔高度和草地类型的变化没有呈现出一定的变化规律，两土层中土壤速效磷/全磷比值(AP/TP)与土壤pH值以及年平均气温呈显著正相关(P＜0.05)，说明该区土壤pH值和温度的变化能显著影响土壤磷的活化；多数样地0-10 cm土层速效磷显著高于10-20 cm土层，可能归因于植物对磷素的表聚作用。

Soil phosphorus and influencing factors in the grasslands at different elevations on west-slope of Helan Mountain,Inner Mongolia

In order to understand the soil phosphorus (P) distribution in different types of grasslands at different elevations and analyze the effects of meteorological factors, soil properties and vegetation on the soil phosphorus, a study was conducted on the west slope of Helan Mountain in Alxa, Inner Mongolia. The results indicated that total soil phosphorus (TP) in both 0-10 and 10-20 cm soil layers declined with decreasing altitude and significantly positively correlated (P＜0.05) with the contents of soil organic carbon and soil particle less than 0.05 mm and vegetation coverage. There was no consistent regularity for vertical distribution of TP content along the soil profiles and distribution of soil available phosphorus (AP) along altitude and grassland types. The ratios of AP/TP in both 0-10 and 10-20 cm soil layers significantly positively correlated (P＜0.05) with soil pH and annual average air temperature which suggesting that soil pH and temperature could significantly affect the activation of soil phosphorus. In most of the plots, AP content in 0-10 cm soil layers were significantly higher than that in 10-20 cm soil layers maybe as the result of surface accumulation effects of vegetation to soil phosphorus.