不同退化阶段高寒草甸土壤化学计量特征

为了阐明不同退化阶段高寒草甸土壤的化学计量特征,沿着高寒草甸退化的梯度选取了原生嵩草草甸、轻度退化草甸和严重沙化草甸,测定了高寒草甸退化过程中不同深度土壤的有机碳、全氮、全磷和全钾含量。结果表明:随着高寒草甸的退化,0～100cm土壤的有机碳、全氮、全磷和全钾含量以及碳氮比、碳磷比、碳钾比、氮磷比、氮钾比和磷钾比均呈降低趋势,且土壤有机碳对高寒草甸退化的敏感性最高,全氮、全磷和全钾的敏感性依次降低,表层20cm的土壤有机碳和全氮可作为表征高寒草甸退化程度最敏感的土壤养分指标。另外,随着草甸的退化,土壤的有机碳、全氮、全磷和全钾含量及其化学计量比的垂直分布明显不同:随着土壤深度的增加,原生嵩草草甸和轻度退化草甸的土壤有机碳、全氮和全磷含量以及碳氮比、碳磷比、碳钾比、氮磷比、氮钾比和磷钾比在0～40cm范围内锐减,在40cm以下缓慢降低并趋于稳定;而沙化草甸土壤的有机碳、全氮、全磷和全钾及其化学计量比随着土壤深度的增加保持不变。

Soil stoichiometry characteristics of alpine meadow at its different degradation stages

To clarify the soil stoichiometry characteristics of alpine meadow at its different degradation stages, the native Kobresia meadow, mildly degraded meadow, and seriously degraded sandy meadow were selected to measure their soil organic carbon (SOC), total nitrogen (N), total phosphorous (P), and total potassium (K) contents at different soil depths. With the degradation of alpine meadow, the SOC, N, P, K, C∶N, C∶P, C∶K, N∶P, N∶K, and P∶K in 0-100 cm profiles presently a decreasing trend, and SOC was most sensitive to the degradation, followed by total N, P, and K. The SOC and N in top (0-20 cm) soil could be used as the most sensitive indicators for the degradation degree of alpine meadow. The vertical distribution of SOC, N, P, and K differed with the degradation stage of the alpine meadow. For native Kobresia meadow and mildly degraded meadow, the SOC, N, P, K, C∶N, C∶P, C∶K, N∶P, N∶K, and P∶K in 0-40 cm soil layer decreased sharply with soil depth, but those in 40-100 cm soil layer had a slow decrease and tended to be stable; for seriously degraded sandy meadow, these stoichiometry characteristics remained unchanged with soil depth.