黄河源河岸带植物根-土复合体抗蚀特性研究

Erodibility of Riparian Zone Alpine Meadow Soil-Root Composite in Source Region of Yellow River

为研究黄河源区河岸在冻融作用下土体抗蚀指数的变化特征,选择黄河源区河岸带3种不同覆被条件的高寒草甸植物群落及裸露地作为研究对象,通过野外原位取样,对其根-土复合体和素土试样进行室内冻融循环试验及抗水蚀试验,结果表明:未经冻融情况下,裸露地表层0~5 cm土体抗蚀指数最小(为2.22%),覆盖度为90%的金露梅+杂草地表层0~5 cm土体抗蚀指数最大(为83.33%),土体抗蚀指数随着植被覆盖度的提高而增大,相同植被覆盖度下土体中根系、有机质含量随着土层深度增加而降低,土体抗蚀指数相应减小;在冻融循环作用下,土体抗蚀指数随着冻融次数的增加总体呈减小的趋势,覆盖度为90%的华扁穗草地土体抗蚀指数下降幅度小于覆盖度为60%的华扁穗草地与覆盖度为90%的金露梅+杂草地的,不同覆盖度土体抗蚀指数在冻融循环9次后减小趋势变缓并有缓慢增大趋势;高覆盖度的华扁穗草和金露梅+杂草地具有较强的抗水蚀作用,对减缓河岸崩塌有一定的作用。

In order to study the characteristics of erosion resistance index of the riverbank soil under the action of freeze thaw,the indoor freeze thaw cycle test and erosion test with different depths were carried out on the soil root composite of the riparian zone alpine meadow area in the source region of the Yellow River.The test results show that the sample’s anti erosion index at bare ground in 0-5 cm depth is the smallest(2.22%),and at Potentilla fruticosa+non gramineous plants sample is the maximum(83.33%),which coverage is 90%and the anti erosion index is increased correspondingly with the increase of vegetation coverage.Under the condition of same coverage,the content of root system and organic matter decline with the decrease of soil depth and the sample’s anti erosion index fall off.Under the action of freeze thaw cycles,the sample’s anti erosion index decreases with the increase of freeze thaw cycles times.The decrease of the sample’s anti ero sion index of 90%coverage Blysmus sinocompressus is less than that 60%coverage Blysmus sinocompressus sample and 90%coverage Po tentilla fruticosa+non gramineous plants sample.When the freeze thaw cycle number reaches to 9,the anti erosion index of three kinds of soil samples is decreased slowly and then there is a slight increase trend.High coverage of Blysmus sinocompressus and Potentilla fruticosa samples has a strong anti water erosion effect and plays a certain role on slowing down the bank collapse.