不同放牧强度下荒漠草原碳密度的变化

Change of carbon density in desert steppe under different grazing intensities

【目的】研究不同放牧强度下荒漠草原植被地上部、根系碳密度及土壤有机碳含量的动态变化,旨在揭示不同放牧强度对荒漠草原植被、土壤碳截存的影响。【方法】在内蒙古苏尼特右旗荒漠草原试验示范基地,设置轻度、中度、重度、极重度放牧和围栏封育(对照区,CK)5个处理,于2012-05-09测定不同放牧强度下荒漠草原植被地上部碳密度、根系碳密度及土壤有机碳含量。【结果】在5-9月,随着放牧强度的增加,荒漠草原植被地上部、0~30cm土层根系碳密度及土壤有机碳含量均呈下降趋势。除轻度放牧区外,其他强度放牧区地上部碳密度与对照区均有明显差异。在不同放牧强度下,荒漠草原地上部碳密度5-9月的动态变化规律一致,均呈单峰型曲线,峰值均出现在8月份。在同一放牧强度下,对照区0~30cm土层根系碳密度随着时间延长而增加,而轻度、中度、重度和极重度放牧区0~30cm土层根系碳密度均呈单峰型变化,峰值出现在7月或8月。在6-9月,与对照区相比,除轻度放牧区0~30cm土层平均土壤有机碳含量增加外,其他放牧强度下土壤有机碳含量均明显降低。【结论】荒漠草原植被地上部和根系碳密度均随放牧强度的增加而降低,轻度放牧有助于土壤有机碳含量的增加。

【Objective】Changes of above/below ground carbon densities and soil carbon content in desert steppe under different grazing intensities were investigated to reveal the influences of grazing intensity on the carbon storage.【Method】In desert steppe trial base in Sonid Youqi,Inner Mongolia,5different treatments including CK,light grazing,moderate grazing,heavy grazing and extremely heavy grazing were set up.The above ground carbon density,root carbon density and soil organic carbon content under different grazing intensities were measured from May to September in 2012.【Result】With the increase of grazing intensity,the above ground carbon density,root carbon density and soil organic carbon content in desert steppe decreased from May to September.The above ground carbon densities in all grazing plots exceptlight grazing plot had significant difference compared to the CK.With the same grazing intensity,the above ground carbon density from May to September showed identical single-peak variation with peak value in August.Root carbon density in the soil layer of 0-30cm in CK increased with time while it showed single peak variation with peak value in July or August in grazing plots.From June to September,the average soil organic carbon content in soil layer of 0-30cm decreased in all grazing plots except light grazing plot compared to CK.【Conclusion】The above ground and root carbon densities in desert steppe decreased as the increase of grazing intensity,and light grazing was beneficial to the increase of soil organic carbon content.