不同草本植物根系对土壤渗透性的影响

Influence of Different Herbaceous Roots on Soil Permeability

[目的]揭示当地排土场不同草本植物根系对土壤渗透性的影响,阐明预测草本植物根系提升土壤渗透性的最优指标,并得出草本植物根系提升土壤渗透性的最佳径级,为排土场生态修复植物选择提供重要依据。[方法]以海州露天矿排土场为研究地点,以轴根型紫花地丁、根蘖型苦荬菜和根茎型水麦冬为研究对象,采用图片像素换算法量化3种根系在不同土层深度范围内的根系分布特征;并结合渗透试验获取3种草本植物原状根土复合体的渗透参数,进而探究了根土复合体根系分布参数与渗透参数的关系。[结果]3种草本植物均能提升土壤的渗透性能,轴根型、根茎型和根蘖型根土复合体的初始入渗率、稳渗率、平均渗透速率、渗透总量相较于素土分别提升82.23%~254.99%,85.59%~307.63%,72.02%~325.91%,62.93%~246.98%。3种草本植物根系的根长密度和根表面积密度与根土复合体的渗透参数均呈现线性相关,根表面积密度的相关性强于根长密度。3种根系对土壤渗透性的增强作用主要归功于0.5 mm<D≤1.5 mm径级,它们均存在提升土壤渗透性的最佳径级。[结论]草本植物根系能够提升土壤渗透性,根表面积密度是最佳预测指标,且不同根系均存在最佳径级。

[Objective]The aims of this study are to reveal the effects of different herb roots on soil permeability in local dump sites,to clarify the optimal index for predicting the improvement of soil permeability by herbaceous plant roots,to obtain the optimal diameter grade of herbaceous plant roots to improve soil permeability,so as to provide an important basis for the selection of ecological restoration plants in the dump.[Methods]Haizhou open pit dump was taken as the study site.The axial root type of Viola philippica,the tiller root type of Ixeris polycephala and the rhizome root type of Triglochin palustris were the objects of the study.The root distribution characteristics of three kinds of roots in different soil depths were quantified by image pixel conversion method.Combined with the penetration test,the permeability parameters of the undisturbed root-soil complex of three herbaceous plants were obtained.The relationship between root distribution parameters and permeability parameters of the root-soil complex was explored.[Results]All three herbs can improve soil permeability.Compared with plain soil,the initial infiltration rate,steady infiltration rate,average infiltration rate and total infiltration rate of axial,rhizoid and tillering root soil composites increase by 82.23%~254.99%,85.59%~307.63%,72.02%~325.91%and 62.93%~246.98%,respectively.The root length density and root surface area density of the three herbaceous roots are linearly correlated with the permeability parameters of the root soil complex,and the correlation of root surface area density is stronger than that of root length density.The enhancement effect of three kinds of roots on soil permeability is mainly attributed to the diameter class of 0.5 mm<D≤1.5 mm,and they all have the best diameter class to enhance soil permeability.[Conclusion]Herbaceous roots can improve soil permeability,and root surface area density is the best predictor,and different roots have the best diameter class.