German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.
Systematic Botany and Functional Biodiversity, Leipzig University, Leipzig, Germany.
Glob Chang Biol. 2022 Mar;28(5):1870-1883. doi: 10.1111/gcb.16028. Epub 2021 Dec 20.
Droughts increasingly threaten the world's forests and their potential to mitigate climate change. In 2018-2019, Central European forests were hit by two consecutive hotter drought years, an unprecedented phenomenon that is likely to occur more frequently with climate change. Here, we examine tree growth and physiological stress responses (increase in carbon isotope composition; Δδ C) to this consecutive drought based on tree rings of dominant tree species in a Central European floodplain forest. Tree growth was not reduced for most species in 2018, indicating that water supply in floodplain forests can partly buffer meteorological water deficits. Drought stress responses in 2018 were comparable to former single drought years but the hotter drought in 2018 induced drought legacies in tree growth while former droughts did not. We observed strong decreases in tree growth and increases in Δδ C across all tree species in 2019, which are likely driven by the cumulative stress both consecutive hotter droughts exerted. Our results show that consecutive hotter droughts pose a novel threat to forests under climate change, even in forest ecosystems with comparably high levels of water supply.
干旱日益威胁着世界森林及其减缓气候变化的潜力。在 2018-2019 年，中欧森林连续遭受了两年更热的干旱，这是一种前所未有的现象，随着气候变化的发生频率可能会更高。在这里，我们根据中欧洪泛区森林中主要树种的年轮，研究了这种连续干旱对树木生长和生理应激反应（碳同位素组成增加；Δδ C）的影响。在 2018 年，大多数树种的生长并没有减少，这表明洪泛区森林的供水可以部分缓冲气象水分亏缺。2018 年的干旱应激反应与以前的单一年份干旱相当，但 2018 年更热的干旱在树木生长中留下了干旱的影响，而以前的干旱则没有。我们观察到 2019 年所有树种的树木生长和 Δδ C 都有强烈的下降，这可能是由连续更热的干旱造成的累积胁迫引起的。我们的研究结果表明，即使在供水水平相对较高的森林生态系统中，连续的更热干旱也对森林构成了新的威胁。
