title: Climatic Signals from Intra-annual Density Fluctuation Frequency in Mediterranean Pines at a Regional Scale.
abstract: Tree rings provide information about the climatic conditions during the growing season by recording them in different anatomical features, such as intra-annual density fluctuations (IADFs). IADFs are intra-annual changes of wood density appearing as latewood-like cells within earlywood, or earlywood-like cells within latewood. The occurrence of IADFs is dependent on the age and size of the tree, and it is triggered by climatic drivers. The variations of IADF frequency of different species and their dependence on climate across a wide geographical range have still to be explored. The objective of this study is to investigate the effect of age, tree-ring width and climate on IADF formation and frequency at a regional scale across the Mediterranean Basin in Pinus halepensis Mill., Pinus pinaster Ait., and Pinus pinea L. The analyzed tree-ring network was composed of P. pinea trees growing at 10 sites (2 in Italy, 4 in Spain, and 4 in Portugal), P. pinaster from 19 sites (2 in Italy, 13 in Spain, and 4 in Portugal), and P. halepensis from 38 sites in Spain. The correlations between IADF frequency and monthly minimum, mean and maximum temperatures, as well as between IADF frequency and total precipitation, were analyzed. A significant negative relationship between IADF frequency and tree-ring age was found for the three Mediterranean pines. Moreover, IADFs were more frequent in wider rings than in narrower ones, although the widest rings showed a reduced IADF frequency. Wet conditions during late summer/early autumn triggered the formation of IADFs in the three species. Our results suggest the existence of a common climatic driver for the formation of IADFs in Mediterranean pines, highlighting the potential use of IADF frequency as a proxy for climate reconstructions with geographical resolution.
authors.affiliation: Department of Agricultural Sciences, University of Naples Federico II Portici, Italy.
authors.forename: Enrica
authors.initials: E
authors.lastname: Zalloni
authors.affiliation: Department of Geography and Regional Planning, Environmental Sciences Institute, University of Zaragoza Zaragoza, Spain.
authors.forename: Martin
authors.initials: M
authors.lastname: de Luis
authors.affiliation: Department of Life Sciences, Centre for Functional Ecology, University of Coimbra Coimbra, Portugal.
authors.forename: Filipe
authors.initials: F
authors.lastname: Campelo
authors.affiliation: Department of Geography and Regional Planning, Environmental Sciences Institute, University of Zaragoza Zaragoza, Spain.
authors.forename: Klemen
authors.initials: K
authors.lastname: Novak
authors.affiliation: Department of Agricultural Sciences, University of Naples Federico II Portici, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: De Micco
authors.affiliation: Department of Agricultural and Forestry Science, Tuscia University Viterbo, Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Di Filippo
authors.affiliation: Department of Life Sciences, Centre for Functional Ecology, University of Coimbra Coimbra, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Vieira
authors.affiliation: Department of Life Sciences, Centre for Functional Ecology, University of Coimbra Coimbra, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Nabais
authors.affiliation: Departamento de Ciencias Agroforestales, Escuela Universitaria de Ingenierías Agrarias, Universidad de Valladolid, Campus Duques de Soria Soria, Spain.
authors.forename: Vicente
authors.initials: V
authors.lastname: Rozas
authors.affiliation: Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of NaplesCaserta, Italy; Laboratoire Paléoenvironnements et Chronoécologie, Ecole Pratique des Hautes Etudes, Institut des Sciences de l'Evolution - UMR 5554, Université de MontpellierMontpellier, France.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Battipaglia
keywords: IADF; Pinus halepensis; Pinus pinaster; Pinus pinea; climate; tree rings