title: The impact of drought on leaf physiology of Quercus suber L. trees: comparison of an extreme drought event with chronic rainfall reduction.
abstract: Understanding the responses of cork oak (Quercus suber L.) to actual and predicted summer conditions is essential to determine the future sustainability of cork oak woodlands in Iberia. Thermal imaging may provide a rapid method for monitoring the extent of stress. The ecophysiology of cork trees was studied over three years. Three treatments were applied by means of rainfall capture and irrigation, with plots receiving 120%, 100%, or 80% of natural precipitation. Despite stomatal closure, detected using both thermal imaging and porometry, leaf water potential fell during the summer, most drastically during the third year of accumulative stress. The quantum efficiency (ΦPSII) and the maximum efficiency Fv' /FM' of photosystem II also fell more intensely over the third summer, while non-photochemical quenching (NPQ) increased. The reduced precipitation treatment sporadically further reduced leaf water potential, stomatal conductance (gs), IG (an index of gs derived from thermal imaging), ΦPSII, and Fv' /FM', and increased leaf temperature and NPQ. It is concluded that these are very resilient trees since they were only severely affected in the third year of severe drought (the third year registering 45% less rainfall than average), and removing 20% of rainfall had a limited impact..
authors.affiliation: Laboratório de Ecofisiologia Molecular, Instituto de Tecnologia Química e Biológica, Quinta do Marquês, 2784-505 Oeiras, Portugal. olga.grant@nuim.ie
authors.forename: Olga M
authors.initials: OM
authors.lastname: Grant
authors.forename: Lukasz
authors.initials: L
authors.lastname: Tronina
authors.forename: José Cochicho
authors.initials: JC
authors.lastname: Ramalho
authors.forename: Cathy
authors.initials: C
authors.lastname: Kurz Besson
authors.forename: Raquel
authors.initials: R
authors.lastname: Lobo-do-Vale
authors.forename: João
authors.initials: J
authors.lastname: Santos Pereira
authors.forename: Hamlyn G
authors.initials: HG
authors.lastname: Jones
authors.forename: M Manuela
authors.initials: MM
authors.lastname: Chaves
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D055864:Droughts; D005453:Fluorescence; D006813:Humidity; D021621:Imaging, Three-Dimensional; D018515:Plant Leaves / Q000502:physiology*; D029963:Quercus / Q000502:physiology*; D011891:Rain; D012621:Seasons; D012987:Soil; D013696:Temperature; D014197:Trees / Q000502:physiology*; D055548:Vapor Pressure; D014867:Water
chemical_list: D012987:Soil; D014867:Water; D002734:Chlorophyll