Suchergebnisse

Global climate change is expected to further raise the frequency and severity of extreme events, such as droughts. The effects of extreme droughts on trees are difficult to disentangle given the inherent complexity of drought events (frequency, severity, duration, and timing during the growing season). Besides, drought effects might be modulated by trees' phenotypic variability, which is, in turn, affected by long‐term local selective pressures and management legacies. Here, we investigated the magnitude and the temporal changes of tree‐level resilience (i.e., resistance, recovery, and resilience) to extreme droughts. Moreover, we assessed the tree‐, site‐, and drought‐related factors and their interactions driving the tree‐level resilience to extreme droughts. We used a tree‐ring network of the widely distributed Scots pine (Pinus sylvestris ) along a 2800 km latitudinal gradient from southern Spain to northern Germany. We found that the resilience to extreme drought decreased in mid‐elevation and low productivity sites from 1980‐1999 to 2000‐2011 likely due to more frequent and severe droughts in the later period. Our study showed that the impact of drought on tree‐level resilience was not dependent on its latitudinal location, but rather on the type of sites trees were growing at and on their growth performances (i.e., magnitude and variability of growth) during the pre‐drought period. We found significant interactive effects between drought duration and tree growth prior to drought, suggesting that Scots pine trees with higher magnitude and variability of growth in the long term are more vulnerable to long and severe droughts. Moreover, our results indicate that Scots pine trees that experienced more frequent droughts over the long‐term were less resistant to extreme droughts. We therefore conclude that the physiological resilience to extreme droughts might be constrained by their growth prior to drought, and that more frequent and longer drought periods may overstrain their potential for acclimation. ; Marie Skłodowska-Curie Individual Fellowship (PROJECT ID: 749051-REFOREST), Postdoctoral grant (IJCI-2015-25845, FEDER funds), RTI2018-096884-B-C31, RTI2018-096884-B-C33 projects (Ministry of Ministry of Science, Innovation and Universities, Spain), VULBOS project (UPO-1263216, FEDER Funds, Andalusia Regional Government, Consejería de Economía, Conocimiento, Empresas y Universidad 2014-2020), PinCaR project (UHU-1266324, FEDER Funds, Andalusia Regional Government, Consejería de Economía, Conocimiento, Empresas y Universidad 2014-2020), Bavarian Ministry of Science, Bavarian Climate Research Network (bayklif). project DENDROKLIMA by the German Waldklimafond (FKZ 28W-C-4-077-01), ST327 Bavarian State Ministry for Food, Agriculture, and Forestry. Landesforst MecklenburgVorpommern, Landeskompetenzzentrum Forst Eberswalde and Nordwestdeutsche Forstliche Versuchsanstalt.