梯度应力下植物根系在固土抗蚀受损后自修复的生物力学响应机制

The selection of soil erosion resistant plant species is the key to conserve soil erosion. Plant roots as a deformable living organism, have the ability of self-repair after soil erosion. This topic is based on four common soil and water conservation plants in Inner Mongolia complex erosion region by wind and water of the Jungar coalfield mining area. The theory and method of material mechanics, elastic-plastic mechanics, soil mechanics, soil and water conservation, and botany are used. The research contents include: i) mechanical and biological responses of plant roots under gradient stress; ii) the mechanical properties of the root system and its interspecies difference; iii) the impact of root microstructure on mechanical properties; iv) the response of plants to mechanical stimulation and organizational strain; v) the anatomical observation of the rootstock under the effect of gradient stress on self-repair; vi) and quantitative analysis of chemical components, and compare with the unimpaired biological microscopic mechanism of the root system after the damage of soil erosion. Through the above research, the biomechanical response mechanism of the root system in the repair of soil erosion will be revealed, in order to provide biomechanical basis for the selection and configuration of ecological restoration of complex erosion by wind and water in mining area and similar areas in Inner Mongolia. The research methods could be used for the similar research.

固土抗蚀植物种的选择是改善侵蚀区水土流失现状的关键。植物根系作为一种可变形的活性有机体，在固土抗蚀受损后具有自修复的能力。本课题以内蒙古风水复合侵蚀区的准格尔煤田矿区排土场4种常见水土保持植物为对象，采用材料力学、弹塑性力学、土力学、水土保持学以及植物学的理论和方法，研究植物根系在梯度应力下的力学和生物学响应过程，揭示根系在固土抗蚀受损后自修复的力学特性及其种间差异性。根系力学性能取决于它的微观结构，植物对力学刺激的响应也与组织应变有关，进行根茎在梯度应力下受损自我愈伤后的解剖学观察，以及化学组分的定量分析，并与未受扰动根茎进行比较，阐明根系在固土抗蚀受损后自修复的微观机理。通过上述内容的研究，揭示植物根系在梯度应力作用下固土抗蚀受损后自修复的生物力学响应机制，为该区域及其相似地区生态修复水土流失防治中植物种的选择及配置提供生物力学方面的科学依据。也为同类研究摸索试验和研究方法。

针对柠条、沙棘、杨柴、紫花苜蓿和沙打旺5种植物0～4mm根径不离体单根施加70%平均极限抗拉力受损待愈伤3个月后的存活特性和对极限抗拉力的影响；及针对柠条、沙棘和紫花苜蓿单根承受70%平均极限抗折力（径向损伤力）自修复3个月、5个月后的存活特性和对极限抗折力的影响；研究整株柠条、沙棘、紫花苜蓿根-土复合体分别承受该植物根土复合体平均极限剪力35%、55%和75%的损伤剪力，自修复1个月、3个月后的存活特性和对根土复合体抗剪特性的影响。主要结论：愈伤3个月后试验根存活率和活力值较平行对照（未受扰动）均有明显的下降，降低值大小顺序为沙棘＞柠条＞杨柴＞沙打旺＞紫花苜蓿。5种植物愈伤3个月后单根极限应变均值大小为紫花苜蓿14.89±0.98C＞沙棘13.35±0.95D＞杨柴12.68±0.82A＞沙打旺12.66±0.76B＞柠条8.68±0.43ABCD，弹性模量均值大小为沙打旺4.12±0.35C＞杨柴3.61±0.12B＞紫花苜蓿2.79±0.14AD＞柠条2.21±0.21A＞沙棘1.64±0.13D。单根极限抗拉力和抗拉强度的值均比平行对照的值低，愈伤自修复后恢复抗侵蚀能力顺序为：紫花苜蓿＞杨柴＞沙打旺＞中国沙棘＞小叶锦鸡儿，活性值稳定性顺序为：紫花苜蓿＞小叶锦鸡儿＞沙打旺＞杨柴＞中国沙棘。总体呈现草本植物的恢复能力优于半灌木和灌木，且根径越大，存活率越低。5种植物在代表根径级0-1.5mm范围内平行对照和自修复后的单根极限抗拉力和抗拉强度大小顺序均为：小叶锦鸡儿＞中国沙棘＞杨柴＞沙打旺＞紫花苜蓿，即灌木＞半灌木＞草本植物。抗折受损愈伤自修复呈现的规律和结论与抗拉受损愈伤自修复的规律和结论一致。3种植物根土复合体在受35%、55%和75%程度3个剪力损伤力自修复1个月后，植株整体存活率分别为76.67%、70%、53.33%，自修复3个月后的存活率分别为100%、93.33%、80%。75%的剪力损伤力对3种植物根系自修复后的抗剪强度影响显著，且抗剪强度最小，55%的损伤力其次，35%的损伤力经一定时间自修复后最能够接近平行对照的固土能力。表明受到的损伤力越小、愈伤自修复时间越长，整体的存活率越高。3种植物相比较，自修复能力大小顺序为柠条锦鸡儿＞沙棘＞紫花苜蓿。