不同退化程度高寒草地土壤有机碳分布特征

在青海省三江源区选择了甘德县青珍乡高寒草甸和玛多县花石峡镇高寒草原典型样区,各划分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),分层采集0~10,10~20和20~30 cm不同深度土层样品,分析土壤有机碳含量。结果表明:研究区内高寒草地土壤表土有机碳含量及有机碳密度均随退化程度的加剧和土层的加深呈显著下降,各退化程度间均差异极显著(P0.01)。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土层有机碳含量在青珍样地分别平均降低了21.7%,38.8%,67.4%和79.6%,花石峡样地分别平均降低了19.4%,44.4%,67.0%和79.7%。表层土壤有机碳及有机碳密度在生态系统退化下变化剧烈,不同土层不同退化程度高寒草甸土壤有机碳含量及有机碳密度均高于高寒草原草地,估计退化下土壤有机碳密度平均下降了16 t/hm2,累积退化下表土有机碳损失可能在12 Pg以上。

Distribution characteristics of soil organic carbon on different degradation degree alpine grassland

In this study,typical areas of alpine grassland in Qingzhen,Gande and Huashixia,Maduo which are located at the source area of the Yellow River,Qinghai Province,China were selected and5 types＇ different degraded degree sampling plots（ non- degradation,light degradation,moderate degradation,heavy degradation,extreme degradation） were identified. Topsoil（ 0 - 30 cm） samples were collected using 10 cm depth interval sampling. And soil organic carbon contents were analyzed.Results showed that soil organic carbon contents and organic carbon density were significant decrease as degradation aggravation and soil layer deepen,and there have extremely significant difference among various degradation degree（ P〈0. 01）. Compared to primary vegetation,topsoil（ 0 - 30 cm）soil organic carbon content declined by 21. 7%,38. 8%,67. 4% and 79. 6% under slightly declined,moderately declined,seriously declined and severely declined degree on Qingzhen sampling plots respectively,and by 19. 4%,44. 4%,67. 0% and 79. 7% on Huashixia sampling plots. In general,topsoil soil organic carbon contents and organic carbon density change dramatically in ecosystem degradation. Soil organic carbon contents and organic carbon density of alpine meadow are higher than that of alpine grassland among various degradation degree and soil layer. It is estimated,topsoil organic carbon density average reduction of 16 t / hm^2 on degeneration. A total of over 12 Pg C may have lost.