不同植被盖度香根草减少沟渠侵蚀和C,N,P流失的有效性

Effects of Different Vegetation Coverage of Vetiver in Reducing Ditch Erosion and C, N, P Loss

[目的]探究植物在降低沟渠侵蚀及减少C,N,P流失方面的影响,为流域沟渠侵蚀防控及污染物治理提供技术支撑。[方法]以中国南亚热带集约化蔗区那辣流域沟渠为研究对象,在沟渠中植入不同植被盖度:全部裸露,植被覆盖度为0(BG);部分覆盖,植被覆盖度1%~40%(SC);大部分覆盖,植被覆盖41%~80%(MC);全覆盖,植被覆盖81%~100%(CC)的草本植物香根草。对4—10月的植草沟渠在降雨后定期实地调查和监测,量化不同植被盖度下沟渠的侵蚀与养分流失特征。[结果](1)4—10月,不同植被盖度沟渠宽度、侵蚀量和C,N,P流失量随着时间的增加逐渐增加,大小均表现为:BG>SC>MC>CC。(2)相比于BG,SC,MC和CC沟渠侵蚀量分别降低了37.01%,71.60%和75.04%;C流失量分别降低了35.56%,70.91%和75.23%,N流失量分别降低了35.89%,71.01%和74.39%;P流失量分别降低了34.22%,70.59%和77.01%。(3)相关性分析表明,沟渠侵蚀量与覆盖度和植物根系密度均达到极显著负相关关系(p<0.01),分别解释了沟渠侵蚀变化的91.94%和89.23%。[结论]流域内植草,随着沟渠植被盖度的增加,沟蚀量和养分流失量逐渐降低,且植被盖度在处理MC和CC之间差异不显著。这一结果在改善其他水源区沟渠的侵蚀及降低污染物方面可提供参考依据。

[Objective]The influences of plants on reducing ditch erosion and C,N and P loss were studied in order to provide technical support for the prevention of ditch erosion and pollution control.[Methods]The study was conducted on ditches of the Nala River basin in the intensive sugarcane growing area of Southern Subtropical China.Vetiver(Vetiveria zizanioides,a herbaceous plant)was planted at different vegetation coverage amounts〔bare ground.vegetation coverage of 0%(BG);somewhat covered,vegetation coverage of 1%—40%(SC);mostly covered,vegetation coverage of 41%—80%(MC);completely covered,vegetation coverage of 81%—100%(CC)〕in the ditches.Regular field investigation and monitoring of planted ditches were conducted after rainfall events from April to October,and the characteristics of erosion and nutrient loss under different vegetation coverage were quantified.[Results]①From April to October,the width,erosion amount,and nutrient loss of ditches with different vegetation coverage gradually increased over time.Values for all three parameters followed the same order of BG>SC>MC>CC;②Compared with BG,the erosion amounts for SC,MC,and CC decreased by 37.01%,71.60%and 75.04%;C loss decreased by 35.56%,70.91%and 75.23%;N loss decreased by 35.89%,71.01%and 74.39%,and P loss decreased by 34.22%,70.59%and 77.01%,respectively;③Correlation analysis showed that the erosion amount for ditches was significantly negatively correlated with vetiver grass coverage and plant root density(p<0.01),accounting for 91.94%and 89.23%of the erosion changes,respectively.[Conclusion]As vegetation coverage increased,ditch erosion and nutrient loss gradually decreased.There were no significant differences in ditch erosion and nutrient loss when vegetation coverage was between MC and CC.These results provide guidance for ameliorating ditch erosion and reducing pollutants in other water source areas.