Understanding water use characteristics of revegetation species is crucial for evaluating plant adaptability and guiding the sustainability of vegetation restoration in semiarid regions. Ecological restoration projects have been implemented for decades in degraded ecosystems, achieving significant changes in vegetation cover. However, water use characteristics of the main tree species at different ages remain poorly understood in such systems. We investigated water use characteristics of Robinia pseudoacacia in plantations of different stand-age (18 and 30 years). The species is the most widely planted tree in revegetation efforts on the Loess Plateau. The δ²H and δ¹⁸O of xylem and soil water within 500 cm of the soil surface and the δ¹³C values of plant leaves were measured during two consecutive hydrological years. The results showed that that water uptake proportions from across the soil columns changed in 18-yr R. pseudoacacia between a drier (2016) and wetter year (2017). In contrast, shallow soil water was largely comparable in a stand of 30-yr R. pseudoacacia in 2016 and 2017, and similarly the pattern of water uptake by roots from the middle and deep soil column was comparable. However, leaf-level water use efficiency (WUE_i) of trees in the older plantation was higher during the wetter year, thereby partly alleviating a low infiltration to precipitation ratio. These findings suggest that different stand-age plantation trees have distinct water use characteristics and display different responses to variations in precipitation. Older plantation trees respond to increased water availability by increasing WUE_i instead of switching water sources. This means that stand-age is an essential factor to be considered in ecological restoration management, which can enhance the effectiveness of vegetation restoration strategies. The study indicates useful input from research to management throughout the continuity of restoration effort.

了解植被物种的用水特征对于评估植物的适应性和指导半干旱地区植被恢复的可持续性至关重要。几十年来，在退化的生态系统中实施了生态恢复项目，实现了植被覆盖率的重大变化。然而，在这样的系统中，对于不同年龄的主要树种的用水特征仍然知之甚少。我们调查了不同树龄（18年和30年）人工林中刺槐的水分利用特征。该物种是黄土高原植被最广泛种植的树木。的δ ² H和δ ¹⁸ 500厘米土壤表面和δ内木质部的O和土壤水¹³在连续两个水文年中测量植物叶片的C值。结果表明，18年的伪阿拉伯树（R. pseudoacacia）在较干燥的年份（2016）和较湿的年份（2017）之间，各土壤柱的吸水率发生了变化。相比之下，在2016年和2017年的30年假洋槐林分中，浅层土壤水在很大程度上是可比的，中土层和深层土壤根系的吸水模式也类似。但是，叶级水分利用效率（WUE _i在较湿润的年份中，较老的种植园中的树木的较高），从而部分缓解了较低的入渗与降水比率。这些发现表明，不同林分的人工林具有不同的用水特征，并且对降水变化表现出不同的响应。较老的人工林通过增加WUE _i而不是切换水源来响应增加的水利用率。这意味着站立时间是生态恢复管理中必须考虑的重要因素，可以提高植被恢复策略的有效性。该研究表明，在恢复工作的整个连续过程中，从研究到管理的有用投入。