title: Annual Cambial Rhythm inPinus halepensisandPinus sylvestrisas Indicator for Climate Adaptation.
abstract: To understand better the adaptation strategies of intra-annual radial growth inPinus halepensisandPinus sylvestristo local environmental conditions, we examined the seasonal rhythm of cambial activity and cell differentiation at tissue and cellular levels. Two contrasting sites differing in temperature and amount of precipitation were selected for each species, one typical for their growth and the other represented border climatic conditions, where the two species coexisted. MatureP. halepensistrees from Mediterranean (Spain) and sub-Mediterranean (Slovenia) sites, andP. sylvestrisfrom sub-Mediterranean (Slovenia) and temperate (Slovenia) sites were selected. Repeated sampling was performed throughout the year and samples were prepared for examination with light and transmission electron microscopes. We hypothesized that cambial rhythm in trees growing at the sub-Mediterranean site where the two species co-exist will be similar as at typical sites for their growth. Cambium inP. halepensisat the Mediterranean site was active throughout the year and was never truly dormant, whereas at the sub-Mediterranean site it appeared to be dormant during the winter months. In contrast, cambium inP. sylvestriswas clearly dormant at both sub-Mediterranean and temperate sites, although the dormant period seemed to be significantly longer at the temperate site. Thus, the hypothesis was only partly confirmed. Different cambial and cell differentiation rhythms of the two species at the site where both species co-exist and typical sites for their growth indicate their high but different adaptation strategies in terms of adjustment of radial growth to environmental heterogeneity, crucial for long-term tree performance and survival.
authors.affiliation: Slovenian Forestry Institute, University of Ljubljana Ljubljana, Slovenia.
authors.forename: Peter
authors.initials: P
authors.lastname: Prislan
authors.affiliation: Slovenian Forestry Institute, University of Ljubljana Ljubljana, Slovenia.
authors.forename: Jožica
authors.initials: J
authors.lastname: Gričar
authors.affiliation: Department of Geography and Regional Planning, University of Zaragoza Zaragoza, Spain.
authors.forename: Martin
authors.initials: M
authors.lastname: de Luis
authors.affiliation: Department of Geography and Regional Planning, University of ZaragozaZaragoza, Spain; Department of Ecology, University of AlicanteAlicante, Spain.
authors.forename: Klemen
authors.initials: K
authors.lastname: Novak
authors.affiliation: Department of Geography and Regional Planning, University of Zaragoza Zaragoza, Spain.
authors.forename: Edurne
authors.initials: E
authors.lastname: Martinez Del Castillo
authors.affiliation: Johann Heinrich von Thünen Institute - Thünen Institute of Wood Research Hamburg, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Schmitt
authors.affiliation: Johann Heinrich von Thünen Institute - Thünen Institute of Wood Research Hamburg, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Koch
authors.affiliation: Department of Biology, Biotechnical Faculty, University of Ljubljana Ljubljana, Slovenia.
authors.forename: Jasna
authors.initials: J
authors.lastname: Štrus
authors.affiliation: Department of Biology, Biotechnical Faculty, University of Ljubljana Ljubljana, Slovenia.
authors.forename: Polona
authors.initials: P
authors.lastname: Mrak
authors.affiliation: Department of Biotechnology and Systems Biology, National Institute of Biology, University of Ljubljana Ljubljana, Slovenia.
authors.forename: Magda T
authors.initials: MT
authors.lastname: Žnidarič
authors.affiliation: Department of Wood Science and Technology, Biotechnical Faculty, University of Ljubljana Ljubljana, Slovenia.
authors.forename: Katarina
authors.initials: K
authors.lastname: Čufar
keywords: Aleppo pine; Mediterranean environment; Scots pine; cambium; light microscopy; temperate environment; transmission electron microscopy; xylem