Max-Planck Institute for Biogeochemistry, Hans Knöll Str. 10, 07745, Jena, Germany.
Faculty of Sciences and Technology, NOVA University of Lisbon, Campus da Caparica, 2829-516, Caparica, Portugal.
New Phytol. 2018 Apr;218(1):15-28. doi: 10.1111/nph.15048.
Accumulating evidence highlights increased mortality risks for trees during severe drought, particularly under warmer temperatures and increasing vapour pressure deficit (VPD). Resulting forest die-off events have severe consequences for ecosystem services, biophysical and biogeochemical land-atmosphere processes. Despite advances in monitoring, modelling and experimental studies of the causes and consequences of tree death from individual tree to ecosystem and global scale, a general mechanistic understanding and realistic predictions of drought mortality under future climate conditions are still lacking. We update a global tree mortality map and present a roadmap to a more holistic understanding of forest mortality across scales. We highlight priority research frontiers that promote: (1) new avenues for research on key tree ecophysiological responses to drought; (2) scaling from the tree/plot level to the ecosystem and region; (3) improvements of mortality risk predictions based on both empirical and mechanistic insights; and (4) a global monitoring network of forest mortality. In light of recent and anticipated large forest die-off events such a research agenda is timely and needed to achieve scientific understanding for realistic predictions of drought-induced tree mortality. The implementation of a sustainable network will require support by stakeholders and political authorities at the international level.
越来越多的证据表明，树木在严重干旱期间面临更高的死亡率风险，特别是在温度升高和蒸气压亏缺（VPD）增加的情况下。由此产生的森林死亡事件对生态系统服务、生物物理和生物地球化学陆地-大气过程都有严重的影响。尽管在监测、建模和实验研究方面取得了进展，这些研究涉及从单株树木到生态系统和全球尺度的树木死亡的原因和后果，但对于未来气候条件下干旱导致的死亡率，仍缺乏普遍的机制理解和现实预测。我们更新了全球树木死亡率地图，并提出了一个路线图，以更全面地了解跨尺度的森林死亡率。我们强调了优先研究领域，这些领域将促进：（1）对树木关键生理响应干旱的新研究途径；（2）从树木/斑块水平到生态系统和区域的扩展；（3）基于经验和机制见解提高死亡率风险预测的准确性；（4）建立一个全球森林死亡率监测网络。鉴于最近和预期的大规模森林死亡事件，这样的研究议程是及时和必要的，以实现对干旱引起的树木死亡率的现实预测的科学理解。可持续网络的实施需要国际层面的利益相关者和政治当局的支持。
