中国温带草地土壤硫的分布特征及其与环境因子的关系

以内蒙古和青藏高原的6种主要草地类型为研究对象,分析了不同类型草地表层土壤硫(S)的分布特征及其与环境因子的关系。结果表明:1)青藏高原草原表层土壤(0—10 cm)的全硫含量(430.8 mg/kg)显著高于内蒙古草原(181.4 mg/kg;P0.01)。土壤硫素一般以有机硫的形式存在,具有植物有效性的土壤无机硫所占比例较少,内蒙古土壤这一比例为14.7%,青藏高原为24.5%。2)土壤硫的含量与土壤C、N的分布格局关系紧密,呈显著正相关关系;与土壤p H呈负相关关系。内蒙古与青藏高原研究区土壤的C/S和N/S值较低,这表明硫可能成为对草原生产力起限制性作用的营养元素。3)内蒙古草原表层土壤全硫、水溶性硫、吸附性硫均与年均温呈显著负相关(P0.05);土壤硫与年均降水呈显著正相关关系(P0.05)。青藏高原草地土壤硫中,除水溶性硫与年均降水呈显著正相关关系外,其余土壤硫含量均未与气候因子呈现显著相关关系。

Spatial variation in surface soil sulfur in the temperate grasslands of china and environmental constraints

Using field data collected in six major temperate grasslands on the Inner Mongolian Plateau and the Tibetan Plateau (Qinghai and Tibet), we analyzed spatial variation in surface soil sulfur and associated environmental constraints. The concentration of sulfur in surface soil (i.e., 0-10 cm depth) was significantly higher in the Tibetan grasslands (430.8 mg/kg) than in the Inner Mongolian grasslands (181.4 mg/kg). The surface soil sulfur was mainly in organic form, and there was relatively little inorganic sulfur at the sampling sites that can be absorbed by plants. The percentages of inorganic sulfur at the sampling sites in the Tibetan and Inner Mongolian grasslands were 24.5% and 14.7%, respectively. The concentrations of surface soil sulfur were significantly positively related to surface soil carbon and nitrogen and negatively related to soil pH. The C/S and N/S ratios were low in all of the study sites, indicating that sulfur could be the major nutrient constraint in vegetation productivity in the temperate grasslands of China. In the Inner Mongolian grasslands, the concentrations of total sulfur, solvent sulfur, and adsorbed sulfur were significantly positively related to annual precipitation and negatively related to annual mean temperature. However, in the Tibetan grasslands, most sulfur types were not associated with climatic factors, except for solvent sulfur, which was significantly positively related to annual precipitation.