黔西北乡土植物篱对典型石漠化区石灰土侵蚀动力学过程的调控

在自然降水条件下,定量研究黔西北喀斯特石漠化区典型乡土植物刺梨在坡耕地产流产沙的变化规律,分析该植物篱控制侵蚀产沙的水动力学机理。结果表明,刺梨植物篱截流、分流作用延缓径流产生及汇流时间,增加喀斯特坡面径流入渗量,减小坡面侵蚀动力。在不同降雨强度条件下,喀斯特坡面入渗率与径流量和产沙量呈负线性相关。植物根系缠绕串连黏结根土,改变土壤的入渗特性,增强土壤抗冲性与抗蚀能力。根系密度随土层深度增加而减少,减沙效应亦变小。土壤抗侵蚀能力与d<1mm的须根密度呈极显著正相关关系,与d≤2mm须根的根量、根长与土壤抗冲指数存在线性回归关系。当I30雨强为2.41mm时,植物篱小区几乎无流水侵蚀,而对照样地侵蚀产生较多泥沙;当I30为4.72,8.35mm时,研究小区皆已侵蚀产沙,并在对照样地侵蚀产生细沟,显示雨强加大,坡面产流动力加强,冲沙携沙能力加大。说明植物篱起到保水固土减沙和对土壤侵蚀水动力过程的调控。喀斯特坡面流侵蚀产沙水动力主要受降雨强度和雨滴动能影响,雨滴侵蚀力的大小取决于雨量、雨强、雨滴大小。侵蚀产沙量与雨强、降雨历时呈显著的幂函数关系。揭示了植物根系固土减沙和提高土壤抗侵蚀水动力的调控机理。

Regulation of Native Hedgerow on the Kinetic Process of Limestone Erosion in Typical Rocky Desertification Areas of Northwest Guizhou

Under natural rainfall conditions, the variations of runoff and sediment yield of typical native plant Rosa roxburghii quantitative studied on karst rocky desertification area of Northwest Guizhou, and the hydrodynamic mechanism of controlling erosion and sediment yield by hedgerow analyzed. The results showed that the interception and diversion of R. roxburghii hedgerow delayed runoff production and confluence time, increased runoff infiltration on karst slopes and reduced erosion power. Under different rainfall intensities, the infiltration rate of karst slope was negatively linearly correlated with runoff and sediment yield. The root system of plants twisted and banded the root soil in series, which changed the infiltration characteristics of the soil and enhanced the erosion resistance and corrosion resistance of the soil. Root density decreased with the increasing of soil depth and sediment reduction effect is also reduced. The soil erosion resistance was significantly positively correlated with the density of fibrous roots less than 1 mm, and linearly correlated with the quantity and length of fibrous roots less than 2 mm and the soil erosion resistance index. When the rainfall intensity of I₃₀ was 2.41 mm, there was almost no runoff erosion in hedgerow plot, but more sediment was produced in the control plot. When I₃₀ was 4.72 mm and 8.35 mm, the erosion and sediment yield of the study plots were all increased, and rills were formed in the control plot, which indicated that the rainfall intensity increased, the productivity of slope surface flow was strengthened, and the sand carrying capacity increased. It showed that hedgerows played an important role in water conservation, soil consolidation and sediment reduction, as well as in regulating the hydrodynamic process of soil erosion. The hydrodynamic forces of runoff erosion and sediment yield on karst slopes were mainly affected by rainfall intensity and kinetic energy of raindrops. The size of raindrop erosion depended on rainfall, rainfall intensity and raindrop size. Erosion sediment yield had a significant power function relationship with rainfall intensity and duration. It is reveals the regulation mechanisms of soil consolidation and sediment reduction by plant roots and the improvement of soil erosion resistance hydrodynamics.