Climatic significance of tree-ring width and intra-annual density fluctuations in Pinus pinea from a dry Mediterranean area in Portugal

Abstract

-In Mediterranean climates trees may go through two periods of dormancy, resulting in special anatomical features such as false rings and other intra-annual density fluctuations (IADFs). In this paper, ring growth and the presence of IADFs were studied in Pinus pinea L. growing in the coastal and inland regions of Alentejo (southern Portugal). In order to identify the triggering factors associated with the IADFs, a new classification was proposed for the IADFs in P. pinea: Type E (latewoodlike cells within earlywood); Type E+ (transition cells between earlywood and latewood); Type L (earlywoodlike cells within latewood) and Type L+ (earlywoodlike cells between latewood and earlywood of the next tree ring). Response function analyses showed that radial growth of P. pinea was strongly correlated with precipitation in southern Portugal. The climatic response of P. pinea was higher in the inland area where the summer drought is more severe, the winter temperatures are lower and the soils have low water-holding capacity, in comparison with the coastal area. IADFs were frequent in P. pinea and most of the IADFs were observed in latewood. The presence of IADFs was correlated with fluctuations in climate parameters during the growing season. The IADF type E+ was linked to precipitation events early in summer. The IADF type L and L+ were associated with above-average precipitation in early autumn.false tree-ring / Mediterranean climate / Pinus pinea / radial growth / wood anatomy Résumé -Signification climatique de la largeur des cernes et des fluctuations intra annuelles de la densité chez Pinus pinea dans une région méditerranéenne sèche du Portugal. Dans les climats méditerranéens, les arbres peuvent traverser deux périodes de dormance, ce qui a pour consé-quence des caractéristiques anatomiques particulières telles que des faux cernes et des fluctuations intra annuelles de densité (IADFs). Dans cet article, la croissance des cernes et la présence de IADFs ont été étudiées chez Pinus pinea L. poussant dans les régions côtières et intérieures de l'Alentejo (sud-ouest du Portugal). Dans le but d'identifier les facteurs déclenchants associés à l'IADFs, une nouvelle classification a été proposée pour l'IADFs chez Pinus pinea : Type E (cellules ressemblant à du bois final dans le bois initial) ; Type E+ (cellules de transition entre bois initial et bois final) ; Type L (cellules ressemblant à du bois initial dans du bois final) et Type L+ (cellules ressemblant à du bois initial entre bois final et bois initial du prochain cerne). Les analyses des fonctions de réponse ont montré que la croissance radiale de Pinus pinea était fortement corrélée avec les précipita-tions dans le sud-ouest du Portugal. La réponse climatique de Pinus pinea a été plus forte dans la zone intérieure où la sécheresse d'été est plus sévère, les températures hivernales plus basses et où les sols ont une plus faible capacité de rétention de l'eau, comparativement aux zones côtières. IADFs a été fréquent chez Pinus pinea et la majorité d'IADFs ...

Influence of tree density on climate-growth relationships in a Pinus pinaster Ait. forest in the northern mountains of Sardinia (Italy)

“…High temperatures along with low amounts of rainfall in August negatively influence RW growth and limit LW formation due to the reduction in water availability caused by the increase in evapotranspiration and soil water evaporation (Campelo et al 2006, Vieira et al 2009). Several dendrochronological studies have found tree-ring growth of Pinus sp.…”

“…The intra-annual growth responses of conifers to local climatic variation have been successfully assessed using information on total ring width, earlywood and latewood widths (Campelo et al 2006, Vieira et al 2009, Rozas et al 2011a, Rozas et al 2011b. Indeed, the distinction between earlywood and latewood can lead to a higher temporal resolution of climategrowth relationships and thus provide a better understanding of the intra-annual growth responses to different climate conditions (Lebourgeois 2000, Zweifel et al 2006, Rozas et al 2011a.…”

Changes in climate-growth relationships and IADF formation over time of pine species (Pinus halepensis, P. pinaster and P. sylvestris) in Mediterranean environments

“…IADFs may appear at different positions within a tree-ring depending on the time of the year when the triggering factor occurred (Campelo et al, 2007;Edmondson, 2010;de Micco et al, 2012). IADF type E is triggered by dry periods during spring and early summer.…”

Has global change induced divergent trends in radial growth of Pinus sylvestris and Pinus halepensis at their bioclimatic limit? The example of the Sainte-Baume forest (south-east France)

“…Cores were polished using successively finer grits of sand paper then cross-dated by means of skeleton-plot established under a binocular microscope (Stokes and Smiley, 1968). No particular intra-annual density fluctuation, conspicuous enough to disturb skeleton plot process, was noticed (Campelo et al, 2006). Each core was then measured using an Eklund measuring device (precision 1/100 mm).…”