CREAF, Cerdanyola del Valles, 08193, Barcelona, Spain.
Universitat Autònoma de Barcelona, Cerdanyola del Valles, 08193, Barcelona, Spain.
New Phytol. 2019 Jul;223(1):22-32. doi: 10.1111/nph.15644. Epub 2019 Jan 19.
Drought-induced tree mortality has major impacts on ecosystem carbon and water cycles, and is expected to increase in forests across the globe with climate change. A large body of research in the past decade has advanced our understanding of plant water and carbon relations under drought. However, despite intense research, we still lack generalizable, cross-scale indicators of mortality risk. In this Viewpoint, we propose that a more explicit consideration of water pools could improve our ability to monitor and anticipate mortality risk. Specifically, we focus on the relative water content (RWC), a classic metric in plant water relations, as a potential indicator of mortality risk that is physiologically relevant and integrates different aspects related to hydraulics, stomatal responses and carbon economy under drought. Measures of plant water content are likely to have a strong mechanistic link with mortality and to be integrative, threshold-prone and relatively easy to measure and monitor at large spatial scales, and may complement current mortality metrics based on water potential, loss of hydraulic conductivity and nonstructural carbohydrates. We discuss some of the potential advantages and limitations of these metrics to improve our capacity to monitor and predict drought-induced tree mortality.
干旱导致的树木死亡对生态系统的碳和水循环有重大影响，预计随着气候变化，在全球森林中这种情况将会增加。在过去十年中，大量研究提高了我们对植物在干旱条件下的水分和碳关系的理解。然而，尽管进行了深入的研究，我们仍然缺乏可推广的、跨尺度的死亡率风险指标。在本观点中，我们提出更明确地考虑水分池可以提高我们监测和预测死亡率风险的能力。具体来说，我们关注相对含水量 (RWC)，这是植物水分关系中的一个经典指标，作为一个潜在的死亡率风险指标，它与生理学相关，并整合了与干旱下的水力学、气孔反应和碳经济相关的不同方面。植物水分含量的测量方法可能与死亡率有很强的机械联系，并且具有综合性、易达到阈值以及相对容易在大空间尺度上进行测量和监测的特点，并且可能补充基于水势、水力传导率丧失和非结构性碳水化合物的当前死亡率指标。我们讨论了这些指标的一些潜在优势和局限性，以提高我们监测和预测干旱导致的树木死亡的能力。
