马尾松人工林地浅沟表层土壤颗粒的空间分布特征

Spatial Difference of Soil Particle Size Distribution in an Ephemeral Gully Under Pinus Massoniana Forest

为研究马尾松林地浅沟侵蚀对地表特征的影响,选取南方红壤区马尾松人工林地发育完整的浅沟为研究对象,采用野外调查与室内试验分析相结合的方法,研究浅沟表层(0—5cm)土壤颗粒分布的空间差异性。结果表明:(1)研究区内表层土壤颗粒中石砾含量较高,约占78.68%,土壤为多砾质沙土,土壤水蚀使得浅沟表层土壤粗化。(2)浅沟不同部位间表层土壤颗粒分布差异明显,其中石砾含量表现为沟底<沟坡<沟缘,沟底的石砾含量极显著小于沟坡和沟缘的含量(P<0.01);极粗砂、中粗砂、细砂粒、粉粒和黏粒含量均表现为沟底>沟坡>沟缘,且沟底的含量均极显著大于沟坡和沟缘的含量(P<0.01);而沟坡和沟缘土壤颗粒含量差异不显著(P>0.05)。(3)沿沟长方向从沟头到沟口,沟底表层土壤中粗颗粒含量呈减小趋势,细颗粒含量呈增大趋势;而沟坡和沟缘趋势正好相反,说明在浅沟沟底中上部主要为侵蚀作用,而在中下部主要为沉积作用。(4)不同粒级土壤颗粒含量最优半方差函数理论模型均为高斯模型,土壤颗粒含量的块金系数最大仅为0.36%,远小于25%,不同粒级土壤颗粒含量表现出强烈的空间自相关性。本研究可为南方红壤区人工林地土壤侵蚀治理提供理论支持。

A well-developed ephemeral gully,which located in Pinus massoniana forests,was selected as study slope.Then,the spatial distribution characteristics of soil particle size in surface layer（0—5 cm）were studied.The results showed that：（1）The gravel content was higher in topsoil,which texture belonged to sandy.The water erosion led to the coarse soil surface.（2）Soil particle size distributions varied with the different topographic position of ephemeral gully,the content of gravel（〉2 mm）showed that the groove〈gully slope〈gully edge,and the gravel content in groove was significantly less than these in gully slope and edge（P〈0.01）.All the Extremely coarse sand,coarse sand,fine sand,silt and clay contents were characterized by groove〉gully slope〉gully edge,and the contents in groove were significantly greater than the gully slope and edge（P〈0.01）.The difference between soil particle contents in gully slope and edge were not significant（P〉0.05）.（3）With the gully length direction from head to mizoguchi,the coarse particle contents decreased in groove,but the fine particle contents increased.And the opposite results were found in gully slope and edge.（4）All the optimal semi-variance functions for different graded soil particles were gaussian model,the largest nugget coefficient of soil particles content is only 0.36%,far less than25%,showing a strong spatial correlation.