坡耕地不同水土保持措施对径流泥沙与土壤碳库的影响

自然降雨条件下,采用标准径流小区法,研究了迤者小流域不同水土保持措施试验区水土流失和有机碳的流失特征.结果表明:(1)泥沙作为土壤有机碳流失的重要载体,导致泥沙结合态有机碳的流失量占总有机碳流失量的82.0％以上,最高达97.33％;(2)与裸露荒地(CK)相比,坡面林草措施和等高反坡阶措施均具有一定的蓄水减流和保土减沙效应,其减流率分别为94.47％、61.70％,减沙率分别为94.81％、64.80％;(3)与CK相比,2种坡面措施均具有减少土壤有机碳储量损失的作用,并在一定程度上减缓了土壤有机碳库的负效应.雨季前后,CK坡面小区有机碳储量的减少率达14.39％,明显高于林草坡面3.83％的减少率和反坡水平阶坡面6.25％的减少率.因此,坡面水土保持措施的实施通过改变下垫面及地表微地形,减少坡面径流及径流所携带的泥沙与养分元素,进而减少坡耕地有机碳的输出.

Properties of runoff, sediment and soil carbon stock under different soil and water conservation measures in sloping farmland

By using standard runoff plots observation method, under the natural rainfall condition, this paper studied the properties of soil and water loss and organic carbon loss under different soil and water conservation measures in the Yizhe small watershed area in Kunming. The results were as follows:(1) As the important carrier of soil organic carbon, the loss of sediment-bonded soil organic carbon accounted for over 82.0% of the total organic carbon loss with runoff, and the maximum proportion could reach 97.33%. (2) Compared with CK, these vegetation cover and reverse-slope level terrace measures had great effects on promoting soil and water conservation and on reducing the runoff and sediment. The reduction rate of runoff by the two measures were 94.47% and 61.70% respectively, and sediment reduction rates of them were 94.81% and 64.80% . (3) Compared with CK, the two measures could reduce the loss of soil carbon storage, and could mitigate the negative effect of soil carbon storage to some extent as well. The reduction rate of soil carbon storage of CK was 14.39% through the rainy season, which was significantly higher than those of vegetation cover and reverse-slope level terrace measures with the reduction rate 3.83% and 6.25% respectively. The results suggested that the soil and water conservation measures had remarkable effect on reducing the loss of soil organic carbon on the slope mainly by changing underlying surface and microtopography of the land surface, interrupting runoff on the slope and reducing the sediment and nutrient elements by the runoff and sediment.