三江并流区水库消落带5种草本根系形态及抗拉特性

为揭示三江并流区水库消落带5种草本植物在浅层土壤中的根系形态及抗拉力学特性,筛选消落带优势固土草本,以澜沧江黄登水库消落带的花叶芦竹(Arundo donax var.versicolor)、风车草(Cyperus alternifolius L.)、美人蕉(Canna indica L.)、菖蒲(Acorus calamus L.)和芦苇(Phragmites communis Trin.)为对象,分析了根系形态,并进行室内单根拉伸试验。结果表明:(1)5种草本根系都发育良好,花叶芦竹和风车草根系的所有形态指标都位居前二,根系较为发达; 5种草本直径大于1 mm的根系长度、表面积和体积在各自总根系中占比最大,且除芦苇外,其余4种草本直径大于2 mm的根系体积占比最大,达到58.53%～92.86%。(2)5种草本根系的平均抗拉力、抗拉强度以花叶芦竹(33.04 N,34.33 MPa)最大,美人蕉(10.26 N,7.54 MPa)最小,根系抗拉力、抗拉强度分别随直径增大呈幂函数增大、减小。(3)5种草本根系平均极限延伸率以菖蒲(24.28%)最大,美人蕉(8.20%)最小; 平均杨氏模量以花叶芦竹(313.44 MPa)最大,菖蒲(70.47 MPa)最小,根系杨氏模量与直径呈幂函数负相关。综上,5种草本都适应了研究区环境,均可作为黄登水库消落带植被重建的候选物种; 直径大于1 mm的根系是5种草本根系的主体,直径大于2 mm的根系整体上对体积贡献最大; 花叶芦竹不仅根系发达,且其抵抗拉伸作用的能力最强,固土能力最强,是黄登水库消落带水土保持的优势草本。研究结果可适当推广到三江并流区和其他水库消落带。

Root Morphology and Tensile Characteristics of Five Kinds of Herbs in Reservoir Fluctuating Zone of Three Parallel Rivers

In order to reveal the root morphology and tensile mechanical properties of five herbaceous plants in the reservoir fluctuating zone of the three parallel rivers, the dominant herbs of soil fixation and erosion resistance were selected. Arundo donax var. versicolor,Cyperus alternifolius L., Canna indica L., Acorus calamus L. and Phragmites communis Trin in the fluctuating zone of Huangdeng Reservoir on the Lancang River were selected as the samples in this study. The root morphology was analyzed and the root tensile property was measured by laboratory tests. The results show that:(1)the roots of the five herbs are well developed, and the root morphological indexes of the Arundo donax var. and the Cyperus alternifolius L. were in the top two, the roots of the two species are relatively developed; the root length, surface area and volume of the Five Herbs with diameter greater than 1 mm account for the largest proportion in their total roots, and the root volumes of the other four herbs with diameter greater than 2 mm account for the largest proportion, reaching 58.53% ～ 92.86%, except the Phragmites communis Trin;(2)the highest average tensile force and tensile strength of the five herbs is the Arundo donax var. versicolor(33.04 N, 34.33 MPa), and the lowest is the Canna indica L.(10.26 N, 7.54 MPa); with the increase of root diameter, the root tensile force and the root tensile strength of five herbs significantly increase, decrease; these relationships can both be well fitted by power function;(3)the maximum single root limit extensile rate of five herbs was the Acorus calamus L.(24.28%)and the lowest was the Arundo donax var. versicolor (8.20%), the maximum average Young's modulus is the Arundo donax var. versicolor(313.44 MPa), and the smallest is the Acorus calamus L.(70.47 MPa). There is a negative correlation between Young's modulus and root diameter. To sum up, the five herbaceous plants are well adapted to the environment of the study area, and can be used as candidate species for vegetation restoration of the fluctuating zone of the Huangdeng reservoir. The morphological indexes of the root system of the Arundo donax var. versicolor and the Cyperus alternifolius L. are significantly higher than those of the other three herbs, and the root system is relatively developed. The ability of the Arundo donax var. to resist the tensile action of the outer boundary is the strongest, and its soil fixation ability is the strongest, the results showed that the dominant herb for water and soil conservation in the fluctuating zone of the Huangdeng reservoir is the Arundo donax var. These results can be appropriately extended to the three parallel rivers area and other reservoir fluctuation zones.