Decline of adult beeches in Franche-Comté after 2018

摘要

© AgroParisTech, 2023.Following the exceptional drought-heatwave event of 2018, decline of adult beeches (Fagus sylvatica L.) became visible at the time of leaf development in spring 2019 along a Gray-Belfort axis, in low-altitude sectors (< 600 m). The magnitude of the phenomenon is related to its impact on trees as well as to its surface area (several thousand hectares), and it affects an area at the heart of the beech distribution and production area. The 2018 water deficit anomaly in this region where such events are highly unusual was the inciting factor. Decline was unexpected (branches or even whole trees died), and occurred on beeches whose crown was most of the time com-plete and densely branched. Different studies have been initiated to better address this phenomenon: spatial quantification of the decline, monitoring of the beech recovery or degradation itineraries depending on how severe the initial symptoms were, identification of vulnerability factors.