退化高寒草甸土壤有机碳组分特征
Characteristics of Soil Organic Carbon Fractions in Alpine Meadow with Different Degradation

在青海省三江源区，选择甘德县青珍乡高寒草甸典型样区，划分5种不同退化程度样地（未退化、轻度退化、中度退化、重度退化和极度退化），10 cm 等深度采集表土土壤样品，分析土壤有机碳和有机碳组分质量分数变化。结果表明，研究区内高寒草甸土壤表土有机碳及组分质量分数随退化程度的加剧和土层的加深而呈显著下降。与原生植被相比，轻度退化、中度退化、重度退化和极度退化下 0~30 cm 土层土壤有机碳质量分数分别平均降低21.7%、38.8%、67.4%和79.6%，土壤轻组有机碳质量分数分别平均降低22.8%、43.9%、68.8%和81.2%，土壤重组有机碳质量分数分别平均降低21.4%、38.3%、67.0%和79.0%。轻组占有机碳的比例为22.02%~27.04%，重组占有机碳的比例为72.96%~77.98%，有机碳量的分布主要集中在重组。总的来看，表层土壤有机碳及组分质量分数在生态系统退化下的变化剧烈。随退化程度的加剧，高寒草甸土壤有机碳质量分数下降迅速，损失严重。
In source area of the Yellow River, Yangtze River and Lancangjiang River in Qinghai province, China, a typical area of alpine meadow in Qingzhen town, Gande county was sampled in this study. Five types of sampling plots was classified according to different degraded degree (undegradation, light degradation, moderate degradation, heavy degradation, extreme degradation). Topsoil （0-30 cm）samples were collected by interval sampling of 10 cm depth. Soil organic carbon and fractions contents were measured. The results showed that contents of soil organic carbon and carbon fractions were dramatically decreased with degradation aggravation and deep soil layer. Compared with the primary vegetation, under the conditions of slight, moderate, serious and extreme degradation, soil organic carbon content of topsoil（0-30 cm）declined by 21.7%, 38.8% ,67.4% and 79.6%, respectively; light fraction of soil organic carbon declined by 22.8%、43.9%、68.8% and 81.2%,respectively, and heavy fraction of soil organic carbon declined by 21.4%,38.3%,67.0% and 79.0%, respectively. The percentage of soil light fraction organic carbon to organic carbon content ranged from 22.02% to 27.04%, and the percentage of soil heavy fraction organic carbon to organic carbon content ranged from 72.96% to 77.98%, which meant that soil organic carbon content mainly distributed in heavy fraction. In general, topsoil soil organic carbon and organic carbon fractions contents changed dramatically in ecosystem degradation. Alpine meadow soil organic carbon content was decreased rapidly as degradation aggravation. Therefore, alpine meadow conservation is significant for the sustainable development of animal husbandry and the protection of terrestrial soil carbon stock in the areas of the Yellow River, Yangtze River and Lancangjiang River.