Tree drought–mortality risk depends more on intrinsic species resistance than on stand species diversity - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement
Article Dans Une Revue Global Change Biology Année : 2024

Tree drought–mortality risk depends more on intrinsic species resistance than on stand species diversity

Haben Blondeel
Céline Meredieu
Damien Bonal
Déborah Corso
Sylvain Delzon
Arsène Druel
Douglas Godbold
Hervé Jactel
Boris Rewald
Julien Ruffault
Kris Verheyen

Résumé

Increasing tree diversity is considered a key management option to adapt forests to climate change. However, the effect of species diversity on a forest's ability to cope with extreme drought remains elusive. In this study, we assessed drought tolerance (xylem vulnerability to cavitation) and water stress (water potential), and combined them into a metric of drought–mortality risk (hydraulic safety margin) during extreme 2021 or 2022 summer droughts in five European tree diversity experiments encompassing different biomes. Overall, we found that drought–mortality risk was primarily driven by species identity (56.7% of the total variability), while tree diversity had a much lower effect (8% of the total variability). This result remained valid at the local scale (i.e within experiment) and across the studied European biomes. Tree diversity effect on drought–mortality risk was mediated by changes in water stress intensity, not by changes in xylem vulnerability to cavitation. Significant diversity effects were observed in all experiments, but those effects often varied from positive to negative across mixtures for a given species. Indeed, we found that the composition of the mixtures (i.e., the identities of the species mixed), but not the species richness of the mixture per se, is a driver of tree drought–mortality risk. This calls for a better understanding of the underlying mechanisms before tree diversity can be considered an operational adaption tool to extreme drought. Forest diversification should be considered jointly with management strategies focussed on favouring drought‐tolerant species.
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Dates et versions

hal-04729697 , version 1 (10-10-2024)

Identifiants

Citer

Renaud Decarsin, Joannès Guillemot, Guerric Le Maire, Haben Blondeel, Céline Meredieu, et al.. Tree drought–mortality risk depends more on intrinsic species resistance than on stand species diversity. Global Change Biology, 2024, 30 (9), pp.e17503. ⟨10.1111/gcb.17503⟩. ⟨hal-04729697⟩
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