山丘区中小河流滩地土壤物理性质及空间分布特征

为探求山丘区中小河流滩地土壤物理性质及空间分布特征,以浙江省龙游县灵山港滩地为试验对象,通过野外取样与室内测定分析,分析研究了山丘区中小河流滩地表层土壤的密度、体积质量、孔隙度、饱和含水率、颗粒组成等滩地土壤物理性质变化与空间分布特征。结果表明,河道沿线滩地土壤物理性质空间差异性显著,主要表现为:(1)从上游至下游,滩地土壤密度沿程降低,中游区段土壤体积质量最小,总孔隙度以及饱和含水率最大。(2)土壤颗粒组成以粗颗粒(粗砂,细砂)为主,在河道纵向上,随着河道坡降变缓,水流能态减小,粗颗粒质量分数降低,细颗粒(粉粒,黏粒)质量分数及土壤粒径分维值(D)增加,滩地土壤颗粒沿程细化。(3)由于水流条件及植被类型的影响,在不同滩位上,高滩处林地土壤细颗粒组质量分数及土壤粒径分维值最高,分别为36.38%和2.66,土壤粒径分维值能够反映出不同沉积环境对土壤颗粒分布的影响。

Soil Physical Properties and Spatial Distribution Characteristics of Floodplains in Medium or Small Hilly Rivers

To explor the soil physical properties and spatial distribution characteristics of floodplains in medium or small hilly river,the soil density,soil bulk density,porosity,saturated water holding capacity,particle composition and fractal dimension of floodplains were studied in Longyou County,Zhejiang Province using field survey methods and laboratory analysis.There were significant differences in soil physical properties in different river segments and land patterns,which was presented in detail as:① soil density decreased from upstream to downstream.In middle reaches,the total porosity and saturation water holding capacity the soil were the largest and the bulk density was the smallest;② soil particles were mainly composed of coarse particles (coarse sand,fine sand).As the river gradient slackened,the content of coarse particles decreased and fine particles (silt,clay) content and the value of fractal dimension (D) increased.Fine soil particles become more and more from upstream to downstream.③ Because of the influence of the flow condition and vegetation types,on a different beach elevation the content of fine particles and the value of fractal dimension (D) of the woodland soil were the highest in high floodplain,which was 36.38 and 2.66 respectively.Soil particle fractal dimension can reflect the influence of sedimentary environment and the land use ways on soil particle size distribution.