Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Key Laboratory of Plant Stress Research, College of Life Science, Shandong Normal University, Jinan 250014, China.
Tree Physiol. 2021 Mar 6;41(3):403-415. doi: 10.1093/treephys/tpaa138.
Hydraulic capacitance and carbohydrate storage are two drought adaptation strategies of woody angiosperms. However, we currently lack information on their associations and how they are associated with species' degree of isohydry. We measured total stem xylem nonstructural carbohydrate (NSC) concentration in the dry and wet seasons, xylem hydraulic capacitance, native leaf water potentials, pressure-volume curve parameters and photosynthetic performance in 24 woody understory species differing in their degree of isohydry. We found a trade-off between xylem water and carbohydrate storage both in storage capacitance and along a spectrum of isohydry. Species with higher hydraulic capacitance had lower native NSC storage. The less isohydric species tended to show greater NSC depletion in the dry season and have more drought-tolerant leaves. In contrast, the more isohydric species had higher hydraulic capacitance, which may enhance their drought avoidance capacity. In these species, leaf flushing in the wet season and higher photosynthetic rates in the dry season resulted in accumulation rather than depletion of NSC in the dry season. Our results provide new insights into the mechanisms through which xylem storage functions determine co-occurring species' drought adaptation strategies and improve our capacity to predict community assembly processes under drought.
水力电容和碳水化合物储存是木本被子植物的两种抗旱适应策略。然而，我们目前缺乏关于它们之间关联的信息，以及它们与物种等水力关系程度的关联方式。我们在干季和湿季测量了 24 种不同等水力程度的木本林下物种的总茎木质部非结构性碳水化合物（NSC）浓度、木质部水力电容、原生叶水势、压力-体积曲线参数和光合性能。我们发现木质部水和碳水化合物储存之间存在权衡，无论是在储存电容方面还是在等水力关系的光谱上。水力电容较高的物种木质部 NSC 储存较低。较少等水力的物种在干季倾向于表现出更大的 NSC 耗竭，并且具有更耐旱的叶子。相比之下，更等水力的物种具有更高的水力电容，这可能增强了它们的耐旱能力。在这些物种中，湿季的叶片展放和干季的更高光合速率导致 NSC 在干季的积累而不是耗竭。我们的研究结果为木质部储存功能如何决定共存物种的抗旱适应策略提供了新的见解，并提高了我们在干旱条件下预测群落组装过程的能力。
