不同护坡草本植物的根系分布特征及其对土壤抗剪强度的影响  

Root distribution features of typical herb plants for slope protection and their effects on soil shear strength

作　　者：李建兴[1] 何丙辉[1] 谌芸[1] 黄茹[1] 陶俊[1] 田太强[1] 

机构地区：[1]西南大学资源环境学院/三峡库区生态环境教育部重点实验室,重庆400715

出　　处：《农业工程学报》2013年第10期144-152,共9页Transactions of the Chinese Society of Agricultural Engineering

基　　金：中央高校基本科研业务费专项资金(XDJK2010C046);国家科技支撑计划项目(2011BAD31B03);国家自然科学基金(40971166)

摘　　要：为明确用于三峡库区植被构建的边坡植物物种根系特征与土壤抗剪强度之间的关系,该文以裸地为对照,应用WinRHIZO(Pro.2004c)根系分析系统对香根草(Vetiveria zizanioides(Lin.)Nash)、百喜草(Paspalum notatum Flugge)、狗牙根(Cynodon dactylon(L) Pers.)和紫花苜蓿(Medicago sativaL.)4种护坡草本的根系特征进行定量分析。研究发现:香根草的根长密度和根表面积密度显著大于其他草本;各草本类型的根长密度、根表面积密度及根重密度均随着土壤深度的增加递减,但随深度的增加,不同草本类型的差异逐步缩小;不同草本类型土壤内摩擦角φ和粘聚力c大小均为:香根草>百喜草>紫花苜蓿>狗牙根>裸地,且随土层深度的增加而降低;随着根长密度、根表面积密度的增大,土壤内摩擦角φ呈显著的对数增长,土壤粘聚力c呈显著的线性增长,且与直径D≤5mm不同径级的根系特征之间存在明显的相关性。结果表明:相对于裸地而言,4种草本均能显著增强土壤内摩擦角φ和粘聚力c,且根系对土壤内摩擦角φ的提高程度大于土壤粘聚力c;根长密度和根表面积密度,尤其是直径D≤5mm径级的根长密度和根表面积密度能很好的表征土壤的抗剪强度,可作为评估土壤抗剪强度的重要参数。Plant root systems play an important role in soil erosion control. To investigate characteristics of root systems of herb vegetation for erosion control in the Three Gorges Reservoir region and their influences on soil shear strength, we used bare land as a control. Four typical herb plants of erosion control, Vetiveria zizanioides （Lin.） Nash, Paspalum notatum Flugge, Cynodon dactylon （L） Pers. and Medicago sativa L., were selected and investigated in the experiments. Circular knives （base area： 30 cm2 , high： 10 cm） were used to take samples from the test area for analysis. Direct shear apparatus was applied to analyze soil shear strength. A root analysis system （WinRHIZOPro.2004c） was used to characterize the root systems. The results indicated that： 1） Vetiveria zizanioides （Lin.） Nash had the largest root length density and root surface area density. 2） Root length density, root surface area density, and root weight density of all typical herb plants were decreased with the increasing of soil depth, but the difference on root length density, root surface area density, and root weight density among different herb plants was not significant with the increasing soil depth. The root length density, root surface area density, and root weight density were 0.92 cm/cm3 , 0.29 cm2/cm3 , and 2.10 mg/cm3 for Cynodon dactylon （L） Pers., 1.01 cm/cm3 , 0.77 cm2 /cm3 and 34.72 mg/cm 3 for Medicago sativa L., 8.12 cm/cm3 , 3.12 cm2 /cm3 and 27.70 mg/cm3 for Vetiveria zizanioides （Lin.） Nash and 1.66 cm/cm3 , 0.71 cm2 /cm3 and 9.26 mg/cm3 for Paspalum notatum Flugge, respectively. 3） Soil shear strength was significantly different in the 4 herb plants. Even in the same herb plant, it had different patterns with the difference of soil layers. The internal friction angle φ and cohesion c declined with the increasing of soil depth. We found that the internal friction angle φ and cohesion c of all herb plants were higher than that of bare land. The sequence from high to low were： Vetiv

关 键 词：水土保持 土壤 剪切强度 护坡植物 根长密度 根表面积密度 剪切位移 

分 类 号：S157.1[农业科学—土壤学] S157[农业科学—农业基础科学]