不同放牧强度下荒漠草原土壤有机碳及其δ~(13)C值分布特征

以内蒙古短花针茅荒漠草原为研究对象,通过测定不同载畜率下土壤部分理化性质、土壤有机碳含量和δ~(13)C值.探讨随放牧强度增加土壤有机碳深度分布和δ~(13)C值的组成差异特征.结果显示:随深度增加.有机碳含量呈线性急剧降低,变化范围在16.17～6.26 g/kg之间,而土壤有机碳的δ~(13)C值不断增大.变化范围在-22.5‰～-14.3‰.放牧对土壤有机碳的影响主要在0-20 cm土层,且放牧强度越大,有机碳含量越低,有机质分解程度越大,δ~(13)C值越偏正,δ~(13)C值的深度变化特征还表明.土壤剖面形成发育过程中当地气候和植被发生了很大的变化,可能实现了由C_4植物占优势向C_3植物占优势的变迁.

Distribution Characteristics of Soil Organic Carbon and Its Stable Carbon Isotope Composition in Desertification Grassland under Different Grazing Intensities

Stipa breviflora desertification grassland in Inner Mongolia were selected as a case to study effect of spatial distribution Characteristics of soil organic carbon and difference in stable carbon isotope composition with the increase of grazing.The results showed that the soil organic carbon contents showed a sharp linear decrease with the depth increasing,being 16.17～6.26 g/kg,but with the depth increase the δ~(13)C value of soil organic carbon also increasing,and the δ~(13)C value are between-22.5‰～-14.3‰.The influence of grazing on soil organic carbon mainly in 0-20 cm layer,and the greater the grazing intensity,the lower the soil organic carbon contents,the greater the degree of organic matter decomposition,and the great the δ~(13)C value.The spatial distribution characteristics of δ~(13)C also shows that the local climate and vegetation changed a lot when soil profile development process,and experienced the changes of C_4 to C_3 in the dominant plant possibly.