干热河谷区4种典型植被土壤抗剪性能影响因素探究

Influencing Factors of Soil Shear Performance of Four Typical Vegetations in Dry-Hot Valley Area

【目的】通过探究金沙江干热河谷地区不同植被类型土壤抗剪性能与土壤理化性质之间的关系,为金沙江干热河谷地区防治水土流失、减少土壤侵蚀提供有效依据。【方法】以金沙江干热河谷地区云南省永仁县的4种典型植被(台湾相思、锥连栎、余甘子、云南松)为研究对象。采用野外调查、室内分析和直剪试验的方法,探讨这4种植被土壤在0~10 cm、10~20 cm、20~30 cm土层深度土壤理化性质对土壤抗剪强度的影响。【结果】(1)不同植被类型土壤理化性质存在显著差异(P<0.05),且随土层深度的变化差异显著(P<0.05);(2)不同植被类型土壤抗剪强度随土层深度的变化存在显著差异(P<0.05)。在4种垂压下,台湾相思植被土壤抗剪强度随土层深度的增加逐渐增大,锥连栎植被土壤抗剪强度随土层深度的增加逐渐减小,其余两种植被土壤抗剪强度随土层深度的变化存在差异性。不同植被类型土壤抗剪强度指标存在显著差异(P<0.05),在10~30 cm土层,台湾相思和余甘子植被土壤仍然有较强的粘聚力。在0~20 cm土层,锥连栎和云南松植被土壤内摩擦角较大;(3)土壤抗剪强度指标与土壤理化性质的相关性分析表明,土壤的抗剪性能与土壤理化性质(含水率、容重、全氮、全钾、全磷、交换镁、水解氮、有机质)之间有着密切关系;(4)通过对土壤理化性质进行因子分析(KMO为0.605,Bartlett球形检验P<0.01)提取了3个公因子,累积贡献率为85.636%。第一公因子包括指标:土壤容重、全钾、全磷,贡献率为40.485%;第二公因子包括指标:水解氮、全氮、有机质,贡献率为31.675%;第三公因子包括指标:含水率、交换镁,贡献率为13.385%。【结论】通过研究金沙江干热河谷区4种典型植被土壤抗剪性能与土壤理化性质之间的关系发现,土壤理化性质对土壤抗剪性能有显著性影响。通过因子分析将多个理化性质指标降维分类后发现,土壤理化性质主要通过影响土壤内摩擦角来影响土壤抗剪强度。综上,云南松和锥连栎两种植被可用来加强浅层土壤的稳定性,台湾相思和余甘子两种植被则更倾向于提升深层土壤的稳定性。

[Objective]The relationship between soil shear strength and soil physical and chemical properties of different vegetation types in the dry-hot valley of Jinsha River was explored to provide an effective basis for preventing soil erosion and reducing soil erosion in the area[.Method]Four typical vegetations(Acacia confusa,Quercus franchetii,Phyllanthus emblica,Pinus yunnanensis)in Yongren County of Yunnan Province in the dry-hot valley of Jinsha River were taken as the research objects.Field investigation,laboratory analysis and direct shear test were used to explore the effects of soil physical and chemical properties on soil shear strength in 0-10 cm,10-20 cm and 20-30 cm soil depths of the four vegetation soils[.Result](1)There were significant differences in soil physical and chemical properties among different vegetation types(P<0.05),and the differences were significant with the change of soil depth(P<0.05).(2)The soil shear strength of different vegetation types varied significantly with soil depth(P<0.05).Under the four vertical pressures,the soil shear strength of Acacia confusa vegetation gradually increased with the increase of soil depth,and the soil shear strength of Quercus franchetii vegetation gradually decreased with the increase of soil depth.The soil shear strength of the other two vegetations varies with the depth of the soil layer.There were significant differences in shear strength indexes among different vegetation types(P<0.05).In the 10-30 cm soil layer,the soil of Acacia confusa and Phyllanthus emblica still had strong cohesion.In the 0-20 cm soil layer,the soil internal friction angle of Quercus franchetii and Pinus yunnanensis was larger.(3)The correlation analysis between soil shear strength index and soil physical and chemical properties showed that there was a close relationship between soil shear performance and soil physical and chemical properties(water content,bulk density,total nitrogen,total potassium,total phosphorus,exchange magnesium,hydrolyzable nitrogen,organic matter,respectively).(4)Three common factors were extracted by factor analysis of soil physical and chemical properties(Kaiser Meyer Olkin=0.605,Bartlett sphericity test P<0.01),and the cumulative contribution rate was 85.636%.The first common factor includes indicators of soil bulk density,total potassium,total phosphorus,with a contribution rate:40.485%;the second common factor includes indicators of hydrolyzed nitrogen,total nitrogen,and organic matter,with a contribution rate of 31.675%;the third common factor includes indicators of water content,exchange of magnesium,with a contribution rate of 13.385%.[Conclusion]By studying the relationship between soil shear resistance and soil physical and chemical properties of four typical vegetations in the dryhot valley of Jinsha River,it was found that the physical and chemical properties of soil have a significant effect on soil shear resistance.After dimension reduction and classification of multiple physical and chemical properties by factor analysis,it was found that soil physical and chemical properties mainly affect soil shear strength by affecting soil internal friction angle.In summary,two kinds of vegetation,Pinus yunnanensis and Quercus franchetii,can be used to strengthen the stability of shallow soil,and two kinds of vegetation,Acacia confusa and Phyllanthus emblica,can be used to improve the stability of deep soil.