香根草植物篱对三峡库区坡耕地侵蚀分布的影响

为探究植物篱对坡耕地侵蚀分布的影响,设置1个坡度(15°)、3个降雨强度(60,90,120 mm/h)和3种坡面条件(裸坡对照CK、植物篱P和仅有植物篱根系R),采用稀土元素氧化物将坡面分成5段(自上而下),开展室内人工模拟降雨试验。结果表明:随着降雨强度的增加,各坡面条件示踪坡段的侵蚀速率和侵蚀量均有所增加,整体上均表现为CK>R>P的趋势,植物篱可以显著降低坡面各部位的侵蚀速率及其侵蚀量,且使得侵蚀产沙主要集中在坡中部的Ce、La和Yb 3个示踪区。与CK坡面条件相比,R与P坡面条件下Sm和Ce示踪坡段对总侵蚀量的平均贡献率分别减少77.15%,90.38%和30.01%,28.35%,而Yb、La和Eu示踪坡段对总侵蚀量的平均贡献率分别增加54.34%,35.39%和12.39%,40.58%以及101.45%,91.31%。研究结果表明,植物篱造成坡面下部侵蚀贡献减小而中上部侵蚀贡献增加,坡面侵蚀部位整体上移,对坡地侵蚀的空间分布有显著影响。

Effects of Vetiveria Zizanioides Hedgerow on the Erosion Distribution of Slope Land in the Three Gorges Reservoir Area

In order to reveal the influence of hedgerow on the erosion distribution of sloping land, the slope was divided into five sections (from top to bottom) by using rare earth element oxides, and the simulated rainfall experiments were conducted at one slope gradient (15°), three rainfall intensities (60, 90 and 120 mm/h) and three slope conditions (CK-control slope, P-hedgerow and R-only hedgerow root). The results showed that with the increase of rainfall intensity, the erosion rate and erosion amount of the tracer slope sections in each slope condition increased, and the overall trend was CK>R>P. The hedgerow could significantly reduce the erosion rate and its erosion amount in all parts of the slope, and the erosion sand production was mainly concentrated in the three tracer areas of Ce, La and Yb in the middle of the slope. Compared with CK slope condition, the average contribution rate of Sm and Ce tracer slope sections to total erosion decreased by 77.15%, 90.38% and 30.01%, 28.35% under R and P slope conditions, respectively, while the average contribution rate of Yb, La and Eu tracer slope sections to total erosion increased by 54.34%, 35.39% and 12.39%, 40.58% and 101.45%, 91.31%, respectively. The results indicated that hedgerow caused a decrease in erosion contribution from the lower part of the slope and an increase in erosion contribution from the middle and upper parts of the slope, which had a significant effect on the spatial distribution of slope erosion by shifting the overall erosion site upward.