不同放牧强度下土壤侵蚀对典型草原土壤有机碳的影响

Effects of Soil Erosion on the Soil Organic Carbon of Typical Steep Under Different Grazing Intensities

针对典型草原土壤侵蚀区的碳储量及碳流失问题,采用野外调查取样和人工模拟降雨相结合的方法,探讨了不同放牧强度下内蒙古大针茅典型草原的土壤侵蚀量、有机碳含量、有机碳流失量的变化情况。结果表明:(1)放牧强度对表层土壤有机碳的影响较大,有机碳储量呈先增加后减少的趋势,表现为轻度放牧>对照>中度放牧>重度放牧,且不同放牧强度下0—40cm土壤有机碳变化明显,为明显的垂直递减趋势;(2)降雨强度对草地土壤侵蚀的影响最大,其次为坡度,放牧强度的影响较小;(3)坡度一定时,土壤有机碳流失量受降雨强度的影响程度远大于放牧强度,降雨强度越大,放牧强度越大,土壤侵蚀量和土壤有机碳流失量就越大。可见,控制放牧强度和因地制宜的分区放牧对于控制草地土壤侵蚀十分必要。

Carbon storage and carbon loss were the serious issues in the soil erosion region of typical steppe.By field investigation and simulated rainfall,effects of grazing intensities on the soil erosion,soil organic carbon storage and carbon loss of typical steppe in Inner Mongolia were studied.The results showed that：（1）The grazing intensity had a great effect on the surface soil organic carbon,and the organic carbon storage increased firstly and then decreased,the ranking was the light grazing〉the no grazing〉the moderate grazing〉the heavy grazing;the soil organic carbon storage in 0—40cm soil layer under different grazing intensity changed significantly and showed a vertical decreasing trend.（2）PFTs were most important,followed by N soil,and finally climate the soil erosion was mainly affected by rainfall intensity,followed by slope,and finally grazing intensity.（3）As for the same slope,the rainfall intensity had a greater influence on soil organic carbon loss than the grazing intensity;the soil erosion and soil organic carbon loss increased with the increasing rainfall intensity and grazing intensity.The findings indicate that it is necessary to control grazing intensity for soil erosion for soil erosion in typical steep.