毛竹和雷竹地下系统结构及生物力学性质

Structure and biomechanical properties of underground system of Moso bamboo and Lei bamboo

利用植物稳定山体边坡是一种环保、经济、可持续的生物工程措施,符合生态文明建设新理念。以亚热带典型散生竹种毛竹和雷竹地下系统结构为研究对象,描述毛竹和雷竹根系在土壤中的空间分布状况,探究影响毛竹和雷竹地下系统生物力学性质的因素。结果表明:随着土层的深入,3个径级的毛竹和雷竹根系长度和体积所占比重均表现出逐渐减少的趋势,0-40 cm土层中集中了80%以上的根系。毛竹和雷竹径级D≤1 mm根系占全部根系长度的比重均为最大,大小依次为雷竹鞭根(83.62%)>雷竹竹根(80.46%)>毛竹鞭根(75.70%)>毛竹竹根(70.45%),毛竹径级D≥2mm根系体积所占比重最大,分别为竹根78.73%和鞭根70.23%,雷竹径级D≥2mm(43.60%)和D=1-2mm(39.76%)竹根体积比例相当,径级D=1-2mm鞭根体积为最大(50.78%);毛竹和雷竹不同生长阶段竹鞭抗拉强度和弹性模量之间均存在显著差异,中龄竹鞭抗拉强度显著高于幼龄和老龄,而中龄竹鞭的弹性模量显著低于幼龄和老龄,说明生长阶段是影响竹鞭抗拉强度和弹性模量的因素;饱和含水率条件下,毛竹和雷竹根系抗拉强度与直径呈负幂函数关系,12%含水率条件下,毛竹鞭根和雷竹竹根抗拉强度和直径仍然呈负幂函数关系,毛竹竹根和雷竹鞭根抗拉强度和直径关系不显著。毛竹和雷竹地下系统抗剪切强度与干物质量均呈幂函数关系,毛竹抗剪切强度增加趋势高于雷竹。

Slope stabilization by vegetation is an environment-friendly,cost-effective,and sustainable biological engineering measure,which fits in with the new concept of ecological civilization construction.We took the underground system of Moso bamboo and Lei bamboo,which were typical scattered bamboo in subtropical zone of China,as study objects to describe the spatial distribution condition of root systems and to explore the factors affecting the biomechanical properties of underground system.The results showed that the proportion of length and volume for three diameter classes presented the trend of gradual decline with the depth of the soil.More than 80%of roots concentrated in the 0-40 cm soil layer.The proportion of length for D≤1 mm diameter class of root system was the highest.The order of proportion was Lei bamboo rhizome root(83.62%),Lei bamboo basal root(80.46%),Moso bamboo rhizome root(75.70%),and Moso bamboo basal root(70.45%).The proportion of volume for D≥2 mm diameter class of Moso bamboo was the biggest with the rhizome root and basal root being 78.73%and 70.23%,respectively.The proportion of volume for D≥2 mm and D=1-2 mm diameter classes for Lei bamboo rhizome root was similar.The volume for D=1-2 mm diameter class was the biggest(50.78%).There were significant differences between the rhizome growth stages of tensile strength and modulus strength for both Moso bamboo and Lei bamboo.The tensile strength of middle-aged rhizome was obvious higher than that of young and old aged rhizome,while the modulus strength of middle-aged rhizome was significant lower than that of young and old aged rhizome.It showed that the growth stage was a factor influencing the biomechanical properties of Moso bamboo and Lei bamboo.The relationship between tensile strength and diameter of Moso bamboo and Lei bamboo root systems were both in negative power function with the saturated moisture content,and that of Moso bamboo basal root and Lei bamboo rhizome root were still in negative power function with 12%moisture content.However,the relationship between tensile strength and diameter of Moso bamboo rhizome root and Lei bamboo basal root were not significant any more.The relationship between shear strength and dry matter quality of underground systems of Moso bamboo and Lei bamboo were both in power function,and the increasing trend of shear strength for Moso bamboo was higher than that of Lei bamboo.