Seasonal variability of foliar photosynthetic and morphological traits and drought impacts in a Mediterranean mixed forest
Sperlich, Dominik (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Chang, C. T. (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Peñuelas, Josep (Universitat Autònoma de Barcelona. Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia)
Gracia, Carles (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Sabaté i Jorba, Santi (Centre de Recerca Ecològica i d'Aplicacions Forestals)

Data:	2015
Resum:	The Mediterranean region is a hot spot of climate change vulnerable to increased droughts and heat waves. Scaling carbon fluxes from leaf to landscape levels is particularly challenging under drought conditions. We aimed to improve the mechanistic understanding of the seasonal acclimation of photosynthesis and morphology in sunlit and shaded leaves of four Mediterranean trees (Quercus ilex L. , Pinus halepensis Mill. , Arbutus unedo L. and Quercus pubescens Willd. ) under natural conditions. Vc,max and Jmax were not constant, and mesophyll conductance was not infinite, as assumed in most terrestrial biosphere models, but varied significantly between seasons, tree species and leaf position. Favourable conditions in winter led to photosynthetic recovery and growth in the evergreens. Under moderate drought, adjustments in the photo/biochemistry and stomatal/mesophyllic diffusion behaviour effectively protected the photosynthetic machineries. Severe drought, however, induced early leaf senescence mostly in A. unedo and Q. pubescens, and significantly increased leaf mass per area in Q. ilex and P. halepensis. Shaded leaves had lower photosynthetic potentials but cushioned negative effects during stress periods. Species-specificity, seasonal variations and leaf position are key factors to explain vegetation responses to abiotic stress and hold great potential to reduce uncertainties in terrestrial biosphere models especially under drought conditions.
Ajuts:	European Commission 238366 European Commission 610028 Ministerio de Economía y Competitividad CGL2011-30590-C02-01 Ministerio de Ciencia e Innovación CSD2008-00040 Ministerio de Ciencia e Innovación CGL2006-01293 Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-274
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Abiotic stress ; Arbutus unedo ; Jmax ; Leaf position ; Leaf traits ; Pinus halepensis ; Quercus ilex ; Quercus pubescens ; Seasonality ; Vc,max
Publicat a:	Tree physiology, Vol. 35 issue 5 (May 2015) p. 501-520, ISSN 0829-318X

DOI: 10.1093/treephys/tpv017

Acceptat 33 p, 990.2 KB

Suplement 11 p, 914.1 KB

Figures 11 p, 1.3 MB

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