黄土高原半干旱区山地密植枣林土壤水分特性研究

Soil water characteristic of a dense jujube plantation in the semi-arid hilly Regions of the Loess Plateau in China

针对陕北黄土丘陵区近年来形成的大规模枣林土壤水分研究薄弱的问题，本研究采用中子仪定位观测方法，探讨了山地密植枣林0~1000 cm土层范围的土壤水分特征变化规律。研究将黄土丘陵半干旱区的密植枣林土壤水分划分为活跃层、难恢复层和稳定层。活跃层是土壤0~200 cm土层，该层土壤水分具有明显的逐月动态变化规律，在枣树生育期内，5月是活跃层，土壤水分最干燥期，7月是土壤水分提升最明显期，10月是土壤水分最高期。土壤水分提升规律和枣树耗水规律一致，即在枣树生长旺盛时期，正是土壤水分提升最快的阶段；在枣树休眠结束和开始萌芽时枣林土壤水分出现最低值。枣林土壤水分难恢复层在200 cm以下，其深度取决于枣林年龄，林龄越大该层次越深，12年生密植枣林土壤耗水深度达到540 cm，其中难恢复层厚度为340 cm。难恢复层之下是土壤水分稳定层。研究认为密植枣林土壤耗水深度小于以往研究的刺槐、柠条和苜蓿等土壤水分消耗深度，山地密植枣林模式对今后研究人工林调控土壤水分有积极意义。

Jujube （Ziziphus jujube Mill. CV. Lizao） is an economically important tree fruit species cultivated in the semi-arid hilly regions of the loess plateau in China. A few studies focused on reporting soil water for this area;so this study aimed to quantify soil water characteristic within 0-1000 cm for dense jujube plantation, using the soil core method and neutron probe. The results showed that：（1） According to soil water dynamic change,the whole soil water profile was stratified into three layers：active layer,difficult re-covery layer,and stable layer. （2）The active layer ranged in the 0-200 cm;Soil water of this layer had ob-vious monthly dynamic change;In May, soil water content was the lowest during the whole growth stage （from May to October）;soil water content increased greatly in July and it reached the maximum value in October. The soil water increasing trend was similar to the jujube water consumption trend. This indicated that the stage for jujube vigorous growth was the period that soil water enhanced greatly, but the soil wa-ter minimum value appeared in the germinating stage and dormant ending stage. （3）The difficult recovery layer was below 200 cm, and the depth range for this layer depended on the age of jujube plantation. When the age of jujube trees was increased, the depth for difficult recovery layer was also increased. Wa-ter consumption depth could reach 540 cm for jujube aged twelve, resulting in a difficult recovery range of 340cm.Below the difficult recovery layer, there was the stable layer. （4）Therefore, the water consumption depth for dense jujube plantation was less than the depth for Robinia pseudoacacia, caragana microphylla, and alfalfa. The dense planting pattern for jujube plantation has a positive effect on regulating and control-ling soil water for artificial forests in the semiarid hilly regions of the loess plateau in the future.