title: Shoot desiccation and hydraulic failure in temperate woody angiosperms during an extreme summer drought.
abstract: Plant water status and hydraulics were measured in six woody angiosperms growing in a karstic woodland, during an extreme summer drought. Our aim was to take advantage of an unusual climatic event to identify key traits related to species-specific drought damage. The damage suffered by different species was assessed in terms of percentage of individuals showing extensive crown desiccation. Stem water potential (Ψstem ) and percent loss of hydraulic conductivity (PLC) were measured in healthy and desiccated individuals. Vulnerability to cavitation was assessed in terms of stem water potential inducing 50% PLC (Ψ50 ). Stem density (ρstem ) was also measured. Species-specific percentage of desiccated individuals was correlated to Ψ50 and ρstem . Crown desiccation was more widespread in species with less negative Ψ50 and lower ρstem . Desiccated individuals had lower Ψstem and higher PLC than healthy ones, suggesting that hydraulic failure was an important mechanism driving shoot dieback. Drought-vulnerable species showed lower safety margins (Ψstem  - Ψ50 ) than resistant ones. The Ψ50 , safety margins and ρstem values emerge as convenient traits to be used for tentative predictions of differential species-specific impact of extreme drought events on a local scale. The possibility that carbohydrate depletion was also involved in induction of desiccation symptoms is discussed.
authors.affiliation: Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127, Trieste, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Nardini
authors.affiliation: Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127, Trieste, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Battistuzzo
authors.affiliation: Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127, Trieste, Italy.
authors.forename: Tadeja
authors.initials: T
authors.lastname: Savi
mesh_terms: D002980:Climate; D003890:Desiccation; D007558:Italy; D019684:Magnoliopsida / Q000033:anatomy & histology / Q000502:physiology*; D018520:Plant Shoots / Q000033:anatomy & histology / Q000502:physiology; D018547:Plant Stems / Q000033:anatomy & histology / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology*; D012621:Seasons; D013045:Species Specificity; D014867:Water / Q000502:physiology*; D014934:Wood / Q000033:anatomy & histology / Q000502:physiology; D052584:Xylem / Q000033:anatomy & histology / Q000502:physiology
chemical_list: D014867:Water
keywords: cavitation; crown desiccation; drought; hydraulic failure; safety margin; stem density; stem water potential; tree mortality