尕海湿地植被退化过程中有机碳及相关土壤酶活性变化特征

以青藏高原东缘尕海湿地不同植被退化程度样地为研究对象,采用定位研究与室内试验相结合的方法,研究植被退化过程对土壤有机碳和土壤酶活性的影响。结果表明:植被退化显著影响土壤有机碳含量和土壤酶活性,降低了土壤有机碳的含量和酶促反应效率,且这种影响随土层深度变化有所不同。四种植被退化阶段有机碳含量和酶活性均值总体上(0～100 cm)表现为未退化>轻度退化>中度退化>重度退化。不同土层中,20～40 cm土层的有机碳含量中度退化>轻度退化;0～10 cm土层中淀粉酶和纤二糖酶中度退化阶段活性值较高;20～100 cm土层中蔗糖酶重度退化阶段活性值最高,纤二糖酶活性重度退化>中度退化。同一退化程度土壤有机碳含量、蔗糖酶和纤二糖酶活性随土层深度增加显著降低(P<0.05);淀粉酶和纤维素酶活性在>40 cm土层中活性值有所上升,整体呈波动下降趋势。

Changes of organic carbon and related soil enzyme activities during vegetation degradation in Gahai Wetland

In order to study the effects of soil organic carbon (SOC) and soil enzyme activities during the vegetation degradation process, the field experiments were conducted in marsh meadow of Gahai Wetland on the eastern edge of Qinghai-Tibet Plateau. The main results were as follows: vegetation degradation significantly affected SOC content and soil enzyme activity, reduced SOC content and enzymatic reaction efficiency, and this effect varied with soil depth. The weighted mean values of organic carbon content and soil enzymes activity in 0-100 cm layers varied in different stages of vegetation degradation of marsh meadow, following an order of non-degradation > light degradation > moderate degradation > heavy degradation. In different soil layers, the organic carbon content in 20-40 cm soil layer was moderate degradation > light degradation, and the activity of amylase and cellobiose in 0-10 cm soil layer was moderate degradation > light degradation. In 20-100 cm soil layer, the activity values of invertase were the highest in heavy degradation stage, and the activity values of fiber disaccharidase showed heavy degradation > moderate degradation. With increasing soil layers, SOC content, invertase and fiber disaccharidase activity decreased significantly (P<0.05), while amylase and cellulase activities showed a fluctuating downward trend on the whole, and enzyme activity value increased slightly in the > 40 cm soil layer.