有序聚类法在土壤水分垂直分层中的应用

针对现阶段土壤水分动态研究中土壤水分垂直剖面分层方法所存在的数学理论依据不足的问题，应用有序聚类法中次序不变性的特点，以晋西黄土残塬沟壑区吉县刺槐林地为研究对象，通过对4个样地0～200 cm土壤水分的定位观测，将土壤水分垂直剖面进行了分层. 研究结果表明，晋西黄土残塬沟壑区刺槐林地土壤水分垂直剖面可分为:土壤水分弱利用层（0～20 cm）、土壤水分利用层（20～100 cm）、土壤水分调节层（100 cm以下）. 通过与现有的同类研究对比，有序聚类法分类结果与其他分类结果较为吻合，表明有序聚类法在严密的数学理论基础上，结合了土壤水分层次的有序性，是土壤水分分层研究的创新. 

Application of sequential clustering method in vertical dividing of soil moisture profiles

In modern researches on soil moisture dynamics,the methods of dividing soil moisture profiles have no rigorous mathematical theory to support.To resolve this omission,we carried out field monitoring in 2005 to the depth of 200 cm on four Robinia pseudoacacia sites in Ji County,western Shanxi Province of the Loess Plateau.Considering that clustering results of sequential clusters did not change the sequence of samples,we used this method to divide the soil water profile of four R.pseudoacacia sites with the data of soil moisture obtained from a fixed field monitoring system.The results indicate that the soil moisture profile of R.pseudoacacia in this area can be divided into three layers: weak moisture utilizing layer(0-20 cm),moisture utilizing layer(20-100 cm) and moisture regulating layer(below 100 cm).This is in almost complete agreement with the results of other researches.The results show that the seguential clustering method has a rigorous mathematical theory foundation.Combining with the sequence of the soil moisture profile,this method is an innovation in the research of dividing soil moisture profiles.