水分梯度下高寒草甸土壤功能性状对放牧强度的响应

Response of alpine meadow soil functional traits to grazing intensity under water gradient

摘要:

【目的】揭示青藏高原暖湿化背景下放牧与水分二者的耦合效应对高寒草甸土壤功能性状的影响。【方法】于 2019 年 6-8 月在青海省海北地区低（A）、中（B）、高（C）3 个水分梯度的高寒草甸实验样地进行不同放牧试验数据的采集。【结果】1）除磷外，各水分梯度土壤全氮和土壤有机质含量均有显著差异，且 B、C 样地土壤全氮含量明显高于 A 样地；2）3 种水分梯度下土壤全氮含量随放牧强度的变化趋势基本一致，均随放牧强度增加呈下降趋势；3）土壤有机质含量表现为随水分梯度增加土壤有机质含量增加，C 样地土壤有机质含量最高而 A 样地最低；4）各水分梯度下地下生物量对放牧强度的响应不甚一致，与 CK 相比，A 样地表现为放牧后地下生物量增加，B 和 C 样地表现为放牧后降低。【结论】土壤功能性状受多因子共同调控，需综合考虑，但对于未退化的高寒草甸生态系统，轻度至中度放牧仍是最优利用策略。

Abstract:

【Objective】 In order to reveal the influence of the coupling effect of grazing and water on the soil func- tional properties of Alpine Meadow under the background of warm and humid Qinghai Tibet Plateau【. Method】 Graz- ing experiments with different intensities were carried out in the alpine meadow experimental plots with three water gradients of low (A)，medium (B) and high (C) in Haibei area of Qinghai Province from June to August 2019. 【Result】The results showed that: 1) except for phosphorus，the contents of soil total nitrogen and soil organic matter in each water gradient were significantly different，and the contents of soil total nitrogen in sample plots B and C were significantly higher than that in sample plot A. 2) the variation trend of soil total nitrogen content under the three wa- ter gradients was basically the same with the increase of grazing intensity，and decreased with the increase of grazing intensity. 3) The content of soil organic matter increased with the increase of water gradient.The content of soil or- ganic matter in sample C was significantly higher than those in the other two samples，and the content of soil organic matter in sample A was the lowest.4) The response of underground biomass to grazing intensity under each water gra- dient was not very consistent.Compared with CK，the underground biomass of sample plot A increased after grazing， and those of sample plots B and C decreased after grazing.【Conclusion】 Soil functional properties are regulated by multiple factors and need to be considered comprehensively.However，for the undegraded alpine meadow ecosystem， light to moderate grazing is still the best utilization strategy.