Disturbances in European beech water relation during an extreme drought

Abstract

In the context of a probable increase in intensity and frequency of extreme summer drought events, a better understanding of the key processes involved in water relations is needed to improve the theoretical foundations of predictive process-based models.

Sacrificing growth and maintaining a dynamic carbohydrate storage are key processes for promoting beech survival under prolonged drought conditions

“…In other words, our experiment induced excess mortality, with 16 times more dead trees than the natural level and 8 times more than the extreme level induced by the 2003 drought and heat-wave event. It should also be noted that our experiment induced a lower pre-dawn potential in twigs (− 2.5 MPa) in August 2015 compared to the one recorded in 2003 (− 2.0 MPa) in a nearby beech forest (Peiffer et al 2014), thus highlighting the extreme stress suffered by our trees. However, although we obtained excess mortality compared to natural mortality rate, we also found that the mortality rate was stable from year to year and did not increase dramatically after 3 years of severe drought as expected.…”

Drought and cold spells trigger dieback of temperate oak and beech forests in northern Spain

“…We found the scenario characterized by lower growth and higher iWUE in declining Q. robur and F. sylvatica trees. This efficient water-use strategy could be caused by increased evapotranspiration rates and reduced g s in F. sylvatica to sustain hydraulic functions but decreasing long-term carbon uptake (Gessler et al, 2007;Peiffer et al, 2014), whereas the risk of carbon starvation should be lower in the more anisohydric Q. robur. The recent reduction of iWUE in declining F. sylvatica trees would suggest a poor regulation of gas and water exchange through leaves leading to excessive water loss through leaves (Hentschel et al, 2016), but not necessarily to hydraulic impairment (Delaporte et al, 2016).…”

From the comfort zone to crown dieback: Sequence of physiological stress thresholds in mature European beech trees across progressive drought

“…In addition, we emphasise two aspects: first, in ecophysiological drought studies on mature beech trees at forest sites, study trees were not exposed to severe drought stress, as early defoliation and drought-induced damage were absent (e.g. Backes and Leuschner, 2000;Aranda et al, 2005;Leuzinger et al, 2005;Nahm et al, 2007;Fotelli et al, 2009;Scherrer et al, 2011;Sitková et al, 2014;Dietrich et al, 2019; but see Peiffer et al, 2014 andSchuldt et al, 2020). Second, responses of beech trees to more severe drought were mainly examined using juvenile or potted trees under experimental conditions (e.g.…”