基于流变学法探究植被恢复下土壤力学稳定性

Rheological Evaluation of Soil Mechanical Stability During Vegetation Restoration

[目的]为探究黄土高原植被恢复过程中土壤微结构稳定性的演变规律。[方法]选取子午岭林区4个不同植被演替阶段的土壤为研究对象,通过流变学方法振幅扫描测试方式测定不同基质势(0,-3,-10 kPa)下土壤抗剪切强度参数和黏弹性参数,并分析其与土壤理化性质之间的关系。[结果](1)土壤抗剪切强度和黏弹性随植被演替阶段的增加而增加,主要是由于植被恢复过程中土壤有机碳、交换性Ca^(2+)、砂粒质量分数增加和Na^(+)下降提高土壤颗粒间的黏附力和摩擦力。(2)土壤抗剪切强度参数随基质势的降低而增加,在低基质势条件下,土壤抗剪切强度参数(G′_(LVE)、τ_(LVE)和τ_(max))与交换性Ca^(2+)、砂粒质量分数相关性不显著,而在高基质势条件下,土壤抗剪切强度参数与交换性Ca^(2+)呈显著正相关(p<0.05),τ_(max)、G′_(LVE)、τ_(YP)和G′_(YP)均与砂粒质量分数呈显著正相关。(3)土壤黏弹性参数(γ_(YP)和I_(Z))随基质势的降低而降低;高基质势条件下土壤黏弹性参数与有机碳呈正相关,且随着基质势的降低,相关性逐渐减弱;不同基质势下黏弹性参数均与黏粒质量分数呈显著负相关。(4)土壤整体力学稳定性在0 kPa时与土壤Ca^(2+)呈正相关,-3 kPa时与土壤粉粒、K^(+)呈负相关,-10 kPa时与黏粒质量分数呈正相关关系。[结论]研究结果揭示土壤在不同植被类型不同基质势下的力学稳定性变化规律及影响机制,为理解黄土高原植被恢复过程中土壤特性的演变提供重要依据,也为未来的土壤保护和生态恢复工作提供理论支撑。

[Objective]This study is aiming to evaluate the dynamic evolution of soil microstructure stability during vegetation restoration on the Loess Plateau.[Methods]Soil samples from four stages of vegetation succession in the Ziwuling forest region were examined.Utilizing the amplitude sweep test method,soil shear strength and viscoelastic parameters were assessed under various matric potentials(0,-3 and-10 kPa).Correlation analyses between these parameters and soil physicochemical properties were conducted.[Results](1)Soil shear strength and viscoelasticity exhibited an increasing trend with advancing vegetation succession stages,attributed primarily to the increasing of soil organic carbon,exchangeable Ca^(2+)and sand content,along with reduced Na+during vegetation recovery.This augmentation contributed to enhanced interparticle adhesion and frictional forces.(2)The soil shear strength parameter increased with the decreasing of matric potential.Under low matric potential conditions,there was no significant correlation between soil shear strength parameters(G′LVE、τ_(LVE)andτ_(max))and exchangeable Ca^(2+)and sand content.Under high matric potential conditions,soil shear strength parameters showed a significant positive correlation with exchangeable Ca^(2+)(p<0.05),whileτ_(max),G′_(LVE),τ_(YP),and G′YP exhibited significant positive correlations with sand content.(3)Soil viscoelastic parameters(γ_(YP)and I z)showed a decreasing trend with declining matric potential.Particularly,under high matric potential conditions,these parameters exhibited a positive correlation with organic carbon content,which gradually attenuated with the decreasing of matrix potential.Viscoelastic parameters were negatively correlated with clay content under different matric potentials.(4)The overall mechanical stability of soil was positively correlated with soil Ca^(2+)at 0 kPa,negatively correlated with soil silt and K^(+)content at-3 kPa,and positively correlated with clay content at-10 kPa.[Conclusion]The changes and influencing mechanism of soil mechanical stability under different vegetation types and different matric potentials were revealed,which provided an important basis for understanding the evolution of soil characteristics in the process of vegetation restoration on the Loess Plateau,and also provided theoretical support for soil protection and ecological restoration in the future.