中文摘要：

采用根钻法（洛阳铲）及干燥法分层获取枣林深层根系的细根干重密度和土壤水分数据,利用有序聚类法对深层土壤水分数据进行垂直分层,划分为3层,即强耗水层（2.0～4.4 m）、弱耗水层（4.4～5.0 m）和微弱耗水层（5.0～7.0 m）。该分层结果能较好地反映出深层根系吸收利用土壤水分的特征,其中强耗水层内,不同土层枣林的细根干重密度波动较大,但土壤水分并未随根系波动而改变,土壤含水率低且较为稳定;弱耗水层内细根干重密度连续减少,土壤含水率呈现增加趋势;微弱耗水层内5.0 m以下土层未发现细根,土壤含水率显著提高。

英文摘要：

In order to investigate the relationship between deep soil water （below 2 m） vertical variation and root distribution in the nine-year-old dense jujube plantation in Loess hilly region. The soil core method and oven drying method were used to determine fine root dry weight density and soil water content. Sequential cluster analysis method was adopted to stratify the whole soil water profile into three layers, i.e. strong depletion layer （2.0 -4.4 m）, less strong layer （4.4 -5.0 m） and weak depletion layer （5.0 - 7.0 m） based on the combined analysis of soil water content and the root dry weight density. This stratification result could well reflect soil water characteristic absorbed by root. In the strong depletion layer, fine root dry weight density decreased fluctuantly with the increase of soil depth, but soil water content was low and stable. While in the less strong layer, fine root dry weight density decreased continuously, soil water content presented increasing tendency. The maximum fine root depth was 5 m, there was no fine root in the weak depletion layer and soil water content increased obviously. This study determine the soil layer range of deep soil water depletion degree in densely jujube plantation. It shows that root distribution characteristic has an important effect on the deep soil water variation.