喀斯特高原峡谷区顶坛花椒与金银花林地土壤抗侵蚀特征

Soil Erosion Resistance Characteristics of Zanthoxylum Bungeanum and Lonicera Japonica Forest Land in Canyon Areas of Karst Plateau

喀斯特石漠化综合治理中经济型植物的选择与种植是遏制石漠化发展势头、改善石漠化地区人居环境,实现当地农民脱贫致富的有效措施。为了探讨喀斯特石漠化综合治理区不同经济型植物的水土保持功能效应,选择喀斯特高原花江峡谷地区普遍种植的乡土植物顶坛花椒纯林(以下简称花椒林)、金银花纯林(以下简称金银花林)、金银花-花椒混交林(以下简称混交林)和撂荒地(以下简称对照)4种类型作为研究对象,探讨其林下土壤的抗侵蚀特征。结果表明:(1)不同类型土壤非毛管孔隙度和总孔隙度越大,土壤入渗能力越好,而土壤容重增大会导致土壤渗透性变差。(2)不同类型土壤抗冲性系数为金银花林(2.02min·g^(-1))大于混交林(0.82min·g^(-1))大于花椒林(0.43 min·g^(-1))大于对照(0.31min·g^(-1))。(3)在土壤的抗蚀性方面混交林的土壤抗蚀性优于金银花林、花椒林和对照。(4)从土壤入渗性能、抗蚀性、抗冲性3方面进行总体评价,混交林有利于提高土壤的抗侵蚀能力。

【Objective】Rocky desertification in karst areas is a leading problem in Guizhou Province,Southwest China,especially the Huajiang Valley,which is one of the most prominent areas suffering from the problem.In order to address this problem with comprehensive ecological measures,it is of great essence for us to recover forest vegetation so as to promote changes in structure of the ecoenvironment in karst areas.However,there are still many major issues waiting to be solved in management of the desertification,for example,what kind of ecological as well as economic plants to be selected,how to make reasonable and effective use of natural elements and people’s subjective sense of motivation under harmonization between the conditions of local eco-environment and the needs for economical development;how to realize sustainable development of the ecology and economy;how to build a society where people and nature coexist harmoniously;and how to teach people to live coexistently with ecology.Therefore,the paper is aimed to address these issues in an attempt to provide some scientific basis for restoration of water reserving forests and construction of eco-environment.To that end,investigations were made in the Huajiang karst gorge area to explore effects of Zanthoxylum planispinum var dintanensis forest and Lonicera japonica forest controlling soil erosion.Four plots of forests were set up for comparison in effect on soil erosion,i.e.Plot A,a tract of pure Zanthoxylum planispinum var dintanensis forest;Plot B,a tract of pure,Lonicera japonica forest;Plot C,a tract of Lonicera japonica-Zanthoxylum planispinum var dintanensis mixed forest;and Plot D,a tract of deserted land.The trees are native in the Huajiang karst valley area.【Method】Three key indices of soil erosion resistance,i.e.soil permeability,soil scour resistance and soil erosion durability,were measured.To measure soil permeability,the cutting ring method was adopted.Based on volume of the water(mm)passing through a cutting ring per unit of time,initial-infiltration rate(mm·min-1),stable-infiltration rate(mm·min-1),and average-infiltration rate(mm·min-1)of water were worked out,and then soil permeability was.To measure soil scout resistance,the undisturbed soil scouring trough method designed by Jiang,et al.was used.It is mainly expressed by how long it takes for water flow to scour one gram of soil at a flow velocity set in line with mean annual rainfall.And to measure soil erosion durability,soil samples collected from the four plots were sifted trough a stack of sieves(7 mm and10 mm)to get soil particles 7~10 mm in size,of which 50 were taken out for erosion test that lasted for10 min.and how many particles were collapsed was recorded every minute for calculation of percentage of the collapsed particles against the total particles tested,the index value of soil erosion durability.【Result】1)In all the soils,regardless of type,the higher the non-capillary porosity and the total porosity,the higher the soil permeability,while,the higher the bulk density,the lower the soil permeability.2)In terms of soil scour resistance,the four plots displayed an order of Plot A(2.02 min·g-1)>Plot C(0.82 min·g-1)>Plot B(0.43 min·g-1)>Plot D(0.31 min·g-1)3.In terms of soil erosion durability,Plot C was in the lead among the four.【Conclusion】After overall evaluations of soil permeability,soil scour resistance and soil erosion durability of the four plots,a conclusion comes as that mixed forest is the most conducive to improvement of soil erosion resistance.