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About the Authors:
Maria João Gaspar
Affiliations Departamento de Genética e Biotecnologia, Universidade de Trás os Montes e Alto Douro, Vila Real, Portugal, Centro de Estudos Florestais, Instituto Superior de Agronomia, ULisboa, Tapada da Ajuda, Lisboa, Portugal
Tania Velasco
Affiliation: Sección Forestal, SERIDA, Finca Experimental La Mata, Principado de Asturias, Spain
Isabel Feito
Affiliation: Sección Forestal, SERIDA, Finca Experimental La Mata, Principado de Asturias, Spain
Ricardo Alía
Affiliations Department of Forest Ecology and Genetics, INIA, Forest Research Centre, Madrid, Spain, Sustainable Forest Management Research Institute, University of Valladolid-INIA, Palencia, Spain
Juan Majada
* E-mail: [email protected]
Affiliations Sección Forestal, SERIDA, Finca Experimental La Mata, Principado de Asturias, Spain, Sección Forestal, CETEMAS, Finca Experimental La Mata, Principado de Asturias, Spain
Introduction
Under the on-going climate change scenario, longer, more frequent and more intense drought periods are expected in south-western Europe [1], and water stress will therefore be a leading constrain on plant survival and productivity [2]. Forest tree populations are thus facing new selection pressures and might be unable to track their bioclimatic envelope [3] over the time scale at which these changes are occurring. There is a strong debate about the potential to adapt to these new environmental conditions, which involves phenotypic plasticity at the individual level, and either genetic adaptation or migration at the population level [4]. But in order to evaluate this possibility, it is necessary to characterize the adaptive genetic variation within forest tree species [5] at different hierarchical levels, particularly at early ages. The first years are the most critical phase for the establishment of forest species since seedlings are extremely susceptibility to resource limitations and it is at this stage that most mortality occurs, playing an important role in natural regeneration [6]. The importance of genetic adaptation in forest trees is stressed by the fact that genetic differentiation between populations and clinal variation along environmental gradients are very common in forest tree species (90% and 78% respectively) and, thus, responding to climate change will likely require that the quantitative traits of populations again match their environments [7].
Nonetheless, we have to consider that drought tolerance in Pinus species involves various processes and mechanisms. The adjustment of pine's hydraulic system to local climatic conditions occurs primarily through modifications of shoot radial...