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Title: Chronic cork oak decline and water status: new insights
Authors: Camilo-Alves, Constança
Vaz, Margarida
Esteves da Clara, Ivone
Almeida Ribeiro, Nuno
Keywords: Quercus suber
Sap flow driving force
Sudden death
Issue Date: 21-Jun-2017
Publisher: Springer
Citation: Camilo-Alves, C., Vaz, M., Esteves da Clara, I., Almeida Ribeiro, N. (2017). Chronic cork oak decline and water status: new insights. New Forests, Volume 48, Issue 6, pp 753–772.
Abstract: Abstract Chronic decline and Sudden death are two syndromes of cork oak (Quercus suber) dieback. Mortality is associated with water stress, but underlying physiological mechanisms are poorly understood. Here, we investigated the physiological performance of declining trees during the summer drought. Leaf water potential, gas-exchange, fluorescence of photosystem II and leaf and root starch concentration were compared in healthy (asymptomatic) and declining trees. Low annual cork increment in declining trees indicated tree decline for several years. All trees showed similar water status in spring. In summer, declining trees showed lower predawn leaf water potential (−2.0 vs. −0.8 MPa), but unexpectedly higher midday leaf water potential than healthy trees (−2.8 vs. −3.3 MPa). The higher midday water potential was linked to by means of strongly reduced stomatal conductance and, consequently, transpiration. This study is pioneer showing that declining trees had high midday water potential. A tendency for lower sap flow driving force (the difference between predawn and midday water potential) in declining trees was also associated with reduced photosynthesis, suggesting that chronic dieback may be associated with low carbon uptake. However, starch in roots and leaves was very low and not correlated to the health status of trees. Declining trees showed lower water-use efficiency and non-photochemical quenching in summer, indicating less resistance to drought. Contrarily to chronic decline, one tree that underwent sudden death presented predawn leaf water potential below the cavitation threshold.
Type: article
Appears in Collections:FIT - Publicações - Artigos em Revistas Internacionais Com Arbitragem Científica
MED - Publicações - Artigos em Revistas Internacionais Com Arbitragem Científica

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