坡位对优势植物分布与根系力学特性影响

Impact of Slope Position on the Distribution and Biomechanical Properties of Roots of Dominant Herbs

本试验选取青海贵德地区席芨滩滑坡区为研究区,以异针茅(Stipa aliena Keng)和阿洼早熟禾(Poa araratica Trautv.)为研究对象,以取样点、坡位和植物种为独立变量,采用单因素方差分析,对供试植物根系力学特性指标进行分析。结果表明:随坡位上升,土体含水率降低,坡顶和坡中低于坡脚;相同坡位处,采样点差异总体上未导致根系力学特性产生显著性差异;坡位对植物根系力学特性产生影响,表现为随坡位升高,阿洼早熟禾根径、抗拉力、拉伸极限应变率增加,而抗拉强度和杨氏模量降低,异针茅则表现出不一致的变化规律;与异针茅相比,阿洼早熟禾根径、抗拉力和拉伸极限应变率较高,而其抗拉强度和杨氏模量较低。研究结果可为干旱半干旱区开展边坡植物生态恢复,以及坡面水土流失、浅层滑坡等灾害防治提供理论支撑。

Xijitan giant landslide located in the Guide county,Qinghai,were selected as the study area;and two herbaceous species(Stipa aliena Keng and Poa araratica Trautv.)growing in such area were selected as the study species.Slope position and species were selected as the independent variables to test their impacts on the soil moisture content,soil natural density,the distribution of the species,and the biomechanical properties of roots of plants in the vegetative communities based on One-way ANOVA analysis.The results show that with slope position increasing,soil moisture content decreased and the slope toe had a higher soil moisture content,followed by slope top and slope middle,respectively.In the same slope position,sampling position leads to insignificant difference on the biomechanical properties of plant roots.However,slope position caused a significant difference on the biomechanical properties of roots,that is,with slope position increasing,the diameter,tensile resistance,and tensile strain at crack of P.araratica roots increased,whereas its tensile strength and Young’s modulus decreased.Conversely,this variation was totally different from that for S.aliena.Besides,compared to S.aliena,P.araratica had a higher variation in its diameter,tensile resistance and tensile strain at crack,but a lower variation in its tensile strength and Young’s modulus.The results could provide a theoretical basis for slope ecological restoration,soil erosion and shallow landslide prevention and control in arid and semi-arid areas of the upper Reaches of the Yellow River.