不同降雨强度下坡地覆盖对土壤有机碳流失的影响

Effects of Downhill Coverage on Soil Organic Carbon Loss Under Different Rainfall Intensities

采用模拟降雨试验研究不同降雨强度下坡地覆盖对因地表径流泥沙流失的有机碳影响。结果表明:降雨强度越高,土壤覆盖度越低,土壤有机碳流失量越高。影响土壤有机碳流失的因素表现为降雨强度>土壤覆盖度>地面坡度。降雨过程中,降雨强度由60mm/h增至120mm/h,土壤有机碳流失量增大。覆盖度较小时,降雨强度对土壤有机碳流失起决定作用。降雨强度≤60mm/h时,植物覆盖层抑制土壤有机碳流失,重度覆盖(覆盖度100%)、轻度覆盖(覆盖度50%)与裸露地(覆盖度0%)相比,土壤有机碳流失量分别减少56.2%和36.3%。同时,土壤有机碳流失量随地面坡度由5°升至10°增加4.6%,初始产流时间提前14s。降雨强度与土壤有机碳流失量呈正相关,土壤覆盖度与泥沙流失量(土壤侵蚀量)以及土壤有机碳流失量呈负相关,径流中土壤有机碳流失量随着土壤侵蚀量同步变化。

Effects of downhill coverage on runoff sediment loss of soil organic carbon were studied by rainfall simulations under different rainfall intensities. The results showed that the runoff loss amount of soil organic carbon increased with increasing rainfall intensity and decreasing soil coverage. Impact of the runoff loss of soil organic carbon was rainfall intensity soil surface coverage ground slope. The loss amount of soil organic carbon increased with the rainfall intensities strengthened from 60 mm/h to 120 mm/h. When soil surface coverage was decreased, rainfall intensity played a decisive role on the runoff loss of soil organic carbon. The vegetation coverage inhibited the runoff loss of soil organic carbon with rainfall intensity ≤60 mm/h. Under this condition, compared with the bare land（0% coverage）, the loss amount of soil organic carbon decreased by 56.2% and 36.3% in severe cover（100% coverage） and mild coverage（coverage 50%）, respectively. Simultaneously, the loss amount of soil organic carbon increased by 4. 6° with the ground slope being changed from 5° to 10°, and the initial runoff was ahead of 14 s. There was a positive correlation between rainfall intensity and the runoff loss of soil organic carbon. Besides, a negative correlation was found both soil coverage and sediment loss（soil erosion） of soil organic carbon. The runoff loss of soil organic carbon changed with soil erosion simultaneously.