Distinct Responses of European Beech (Fagus sylvatica L.) to Drought Intensity and Length—A Review of the Impacts of the 2003 and 2018–2019 Drought Events in Central Europe

Abstract

A combined severe heatwave and drought, starting in 2018 and lasting for several months, restarted the discussion on the resistance of European beech to climatic changes, with severe growth reductions, early leaf senescence, leaf browning, and diebacks reported across Central Europe. These responses may result in long-term impacts such as reduced vitality of beech, especially under potential future drought periods. While the 2003 drought caused severe crown damage and defoliation and a loss in vitality, resulting in insect and fungal infestations and subsequent dieback, the drought in 2018 was even more severe in terms of geographical scale, duration, and intensity with reports of complete diebacks and severe mortality across Central Europe. These impacts were exacerbated in some regions by the consecutive drought in 2019 and secondary attacks from pathogens, as well as a further loss in vitality. Such enhanced drought exposure of beech trees could push them beyond their hydraulic safety margins. Moreover, growth legacy effects due to past droughts may lead to lower recovery over time, potentially leading to subsequent tree death. In order to better predict the future of beech growth and vitality in Central Europe, both short- and long-term legacy effects of defoliation and their influence on post-drought growth should be explored, and adaptive forest management strategies evaluated. Moreover, synergistic or additive interactions of legacy effects with drought, as well as with biotic disturbances, require further investigation. Long-term forest monitoring data facilitates investigations of drought responses of beech.

Nutrient and Growth Response of Fagus sylvatica L. Saplings to Drought Is Modified by Fertilisation

“…The latest research shows that recent droughts have seriously impacted beech forests [17][18][19]. Depleted soil moisture conditions during drought can significantly affect tree physiology, affecting tree growth and mortality rates [20,21].…”

Long‐term drought triggers severe declines in carabid beetles in a temperate forest

“…3, 6) may be linked to the 2003 drought but are far surpassed by recent declines. In line with these findings, several studies reported that the impacts on forest ecosystems during the 2003 drought were superseded by those of the drought in 2018/2019 (Buras et al 2020, Schnabel et al 2022, Rukh et al 2023. Forests have the capacity to mitigate the direct effects of extreme weather and shorter-term droughts (Davis et al 2019, Gohr et al 2021).…”

“…Nevertheless, forest ecosystems are increasingly under pressure by climate change (Oakes et al 2014, Seidl et al 2017, Senf et al 2018, Martinez del Castillo et al 2022). Recent droughts in 2003 and in 2018/2019 had significant negative impacts on European temperate forests (Senf et al 2020, Senf and Seidl 2021, Schnabel et al 2022, Rukh et al 2023) and were followed by another drought in 2022, which has recently been described as unprecedented in 500 years (Schumacher et al 2023, Henley 2022). These events potentially had large effects on biodiversity in general (Archaux and Wolters 2006) and on insects in particular (Pureswaran et al 2018, Gely et al 2020, Cours et al 2023, Blüthgen et al 2023).…”

Impacts and damages of the European multi-year drought and heat event 2018–2022 on forests, a review

“…Legacy of a drought event in forests can take many forms (Müller & Bahn 2022, Rukh et al 2023, depending on the tree demography most influenced. The mortality of adult trees can create opening in a forest, influencing the long-term profitability of an economic forest but also the carbon and water cycle and species composition.…”