Thresholds for persistent leaf photochemical damage predict plant drought resilience in a tropical rainforest

Fortunel Claire, Stahl Clément, Coste Sabrina, Ziegler Camille, Derroire Géraldine, Levionnois Sébastien, Marechaux Isabelle, Bonal Damien, Herault Bruno, Wagner Fabien, Sack Lawren, Chave Jérôme, Heuret Patrick, Jansen Steven, John Grace, Scoffoni Christine, Trueba Santiago, Bartlett Megan K.. 2023. Thresholds for persistent leaf photochemical damage predict plant drought resilience in a tropical rainforest. New Phytologist, 239 (2) : 576-591.

https://doi.org/10.1111/nph.18973

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

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Résumé : Water stress can cause declines in plant function that persist after rehydration. Recent work has defined 'resilience' traits characterizing leaf resistance to persistent damage from drought, but whether these traits predict resilience in whole-plant function is unknown. It is also unknown whether the coordination between resilience and 'resistance' – the ability to maintain function during drought – observed globally occurs within ecosystems. For eight rainforest species, we dehydrated and subsequently rehydrated leaves, and measured water stress thresholds for declines in rehydration capacity and maximum quantum yield of photosystem II (Fv/Fm). We tested correlations with embolism resistance and dry season water potentials (ΨMD), and calculated safety margins for damage (ΨMD – thresholds) and tested correlations with drought resilience in sap flow and growth. Ψ thresholds for persistent declines in Fv/Fm, indicating resilience, were positively correlated with ΨMD and thresholds for leaf vein embolism. Safety margins for persistent declines in Fv/Fm, but not rehydration capacity, were positively correlated with drought resilience in sap flow. Correlations between resistance and resilience suggest that species' differences in performance during drought are perpetuated after drought, potentially accelerating shifts in forest composition. Resilience to photochemical damage emerged as a promising functional trait to characterize whole-plant drought resilience.

Mots-clés Agrovoc : résistance à la sécheresse, forêt tropicale humide, stress dû à la sécheresse, changement climatique, embolie, croissance, saison sèche, réhydratation, sécheresse, résilience, feuille, échange gazeux, translocation