Pinheiro Silvestre em Portugal: "extremo sudoeste" ou apenas o "fim?"

Pinus sylvestris L. is widely distributed in Europe and Asia and it constitutes the pine species with largest natural distribution. The

adaptation to a diversity of ecological situations allowed the differentiation of more than 150 geographic races and local adapted

varieties.

Portugal it is the most occidental limit of Scots pine distribution and the presence of a probable native population in ‘Serra do Gerês’

has long surprised botanists and ecologists. This hypothetical outlier in the species geographical range of distribution is confined to a

few riparian areas of ‘Serra do Gerês’ and no attempts to ensure its native origin were made. In recent years, peripheral populations,

like this, have captured the attention of scientists due to their importance for understanding the evolutionary history of forest species,

especially in refugee Mediterranean areas. These rear edge populations are genetically impoverished, more prone to extinction and

have low priority in conservation. However, recent studies have highlighted the interest of their study once they are long-lived species

which faced a multitude of selective forces, ensuring their survival after repeated bottlenecks. During its adaptation process, these

populations supported environmental changes such as alterations in the soil chemical composition, temperature and radiation

incidence, and different regimes of precipitation which modulated their distribution, natural regeneration and phenotypes. Plants have

phenotypic plasticity which is characterized by phenotypic alterations in response to environmental changes in order to reach stability.

Some methodologies have been applied to forestry species in order to estimate their phenotypic plasticity and to infer about its

evolutionary history.

Wood is a temporal record of environment interactions and in temperate climate growing conifers, the typical patterns of earlywood-

latewood reflect the variation in water availability and demand. The study of wood density and X-ray profiles could lead to estimation

of environmental changes and how it affects the production and features of wood, providing inferences about individual plasticity.

Other methodology that could determine the water use efficiency (WUE) is the foliar d13C which reflects drought physiological

responses. Physiological parameters such as survival and growth rates, phenols and pigment amount, and shoot phenology could

establish inferences and comparisons about the adaptive potential of populations from different provenances. The quantification of

expression of genes related to physiological behaviours under abiotic stress, in individuals from different provenances, could also be

useful for understanding phenotypic plasticity, once it involves physiological and morphological responses.

In last decade, molecular markers have been used in forest genetics. Despite their utility for assessing genetic diversity and structure,

gene flow, and phylogenies, neutral markers have been considered insufficient for determining the adaptive potential of forestry

species. Nonetheless, the complementation of molecular and quantitative information derived from dendroplasticity, physiological,

geographical and biometric studies could provide deeper insights about the phenotypic plasticity of a species and to infer about its

adaptive potential under the future climatic changes. Trees will face high temperature increases within only one generation. Within

this critical period they won’t be able to adapt through migration, neither the short time change will allow a multi-generation in-situ

genetic adaptation. Phenotypic plasticity will be the only adaptation mechanism available for survival. Thus, the next generation will

be produced according to their respective fitness. Beyond that moment, genetic diversity will play a central role. The high phenotypic

plasticity of P. sylvestris was already reported for individuals from Nordic countries. To answer to the title question, we intend to

develop a multidisciplinary approach to study the probable native origin of the ‘Serra do Gerês’ population in the context of the

remaining areas (resultant from plantation) of Scots pine in Portugal that we aim to characterize at different levels. In this project, it

will be also included (in some tasks) foreign testers from Spain (2 locals), Germany, France and Scandinavia, in order to represent, at

some extent, the European distribution of the species. We also intend to compare results achieved in Portugal with those previously

reported by other authors in peripheral populations from the Mediterranean refugee areas. Thus, we intend to identify individuals with

the better adaptive behaviour, which may constitute an important source of reproductive material to other countries that will face in a

nearby future, as a result of climate changes, similar situations to those that are occurring nowadays in Portugal.