Zhao Wenyue, Ji Xibin, Chen Rui, Du Zeyu, Jin Bowen, Zhou Hai, Zhao Liwen, Li Dongsheng
Linze Inland River Basin Research Station, State Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
University of Chinese Academy of Sciences, Beijing 100039, China.
Tree Physiol. 2025 Sep 6. doi: 10.1093/treephys/tpaf110.
Leaves constitute a vital bottleneck in whole-plant water transport, and their water strategies are key determinants of plant competition and productivity. Nonetheless, our knowledge of leaf water strategies predominantly stems from single perspectives (i.e., hydraulic, stomatal, or economic traits), severely limiting our capacity to comprehensively predict plant vulnerability and sustainability, especially under drought-stress conditions. Here, we examined the leaf hydraulic, stomatal, and economic traits of three coexisting shrub species (i.e., Haloxylon ammodendron, Calligonum mongolicum, and Nitraria sphaerocarpa) in the Badain Jaran desert-oasis ecotone to comprehensively evaluate their water strategies and drought adaptation mechanisms. The results demonstrated that these three shrubs exhibited significant differences in leaf hydraulic vulnerability, osmoregulatory capacity, stomatal behavior, and economic traits. Nonetheless, these traits remain tightly related to guarantee their survival. Interestingly, two distinct interaction mechanisms between stomatal and hydraulic regulation were identified among the three shrubs with varying stomatal sensitivity. Specifically, N. sphaerocarpa and H. ammodendron employed relatively lower isohydric stomatal behavior, characterized by a synergistic decrease in vapor-phase water loss as liquid-phase water transport decreased during severe atmospheric drought. Conversely, C. mongolicum adopted higher isohydric stomatal behavior, rapidly reducing vapor-phase water loss during initial drought stress to compensate for its more vulnerable liquid-phase water transport system. Notably, all three shrubs presented risky leaf water strategies with negative hydraulic safety margins. Among them, the hydraulic dysfunction risk was lowest for C. mongolicum, followed by N. sphaerocarpa and H. ammodendron. Overall, our findings are anticipated to offer valuable insights for afforestation initiatives and ecological conservation efforts in desert-oasis ecotones that function as critical shelterbelts.
叶片是整株植物水分运输的关键瓶颈，其水分策略是植物竞争力和生产力的关键决定因素。然而，我们对叶片水分策略的了解主要来自单一视角（即水力、气孔或经济性状），这严重限制了我们全面预测植物脆弱性和可持续性的能力，尤其是在干旱胁迫条件下。在此，我们研究了巴丹吉林沙漠-绿洲交错带三种共存灌木物种（即梭梭、沙拐枣和白刺）的叶片水力、气孔和经济性状，以全面评估它们的水分策略和干旱适应机制。结果表明，这三种灌木在叶片水力脆弱性、渗透调节能力、气孔行为和经济性状方面存在显著差异。尽管如此，这些性状仍紧密相关以确保它们的存活。有趣的是，在三种气孔敏感性不同的灌木中发现了两种不同的气孔与水力调节之间的相互作用机制。具体而言，白刺和梭梭采用相对较低的等水气孔行为，其特征是在严重大气干旱期间，随着液相水分运输减少，气相水分损失协同降低。相反，沙拐枣采用较高的等水气孔行为，在初始干旱胁迫期间迅速减少气相水分损失，以补偿其更脆弱的液相水分运输系统。值得注意的是，所有三种灌木都呈现出具有负水力安全边际的风险叶片水分策略。其中，沙拐枣的水力功能障碍风险最低，其次是白刺和梭梭。总体而言，我们的研究结果有望为作为关键防护林带的沙漠-绿洲交错带的造林计划和生态保护工作提供有价值的见解。
