title: Sex-specific, age-dependent sensitivity of tree-ring growth to climate in the dioecious tree Juniperus thurifera.
abstract: Tree features may modulate the sensitivity of radial growth to climate, leading to a nonuniform response. Age-related increases in climatic sensitivity have been observed repeatedly. Sex-related climatic sensitivity is also possible because of the long-term differential reproductive cost between the sexes. This study analysed the simultaneous effects of age and sex on the sensitivity of tree-ring growth to climate. Ring widths were measured from 50 female and 50 male Juniperus thurifera trees, 50-350 yr old, growing under a Mediterranean continental climate. Response functions were calculated based on tree-ring chronologies and monthly climatic records. Climatic sensitivity decreased with increasing age. Young trees (50-100 yr) were the most climatically sensitive to June-July precipitation, which affected growth positively. We found a significant interaction between age and sex in the climatic response of J. thurifera, with young females the most sensitive to summer water stress. Our results suggest that age-dependent climatic sensitivity can be determined by site-specific limiting environmental conditions and species-specific architectural and physiological adjustments during ontogeny. This study supports that the different ontogenetic stages of J. thurifera differ in their root structural traits and that sex-related sensitivity to summer drought may be attributable to less efficient water use by females.
authors.affiliation: Departamento de Ecología, CINAM de Lourizán, Xunta de Galicia, Apdo. 127, 36080 Pontevedra, Spain.
authors.forename: Vicente
authors.initials: V
authors.lastname: Rozas
authors.affiliation: Laboratorio de Botánica, EUI Agrarias de Soria, Universidad de Valladolid, Los Pajaritos s/n, 42004 Soria, Spain.
authors.forename: Lucía
authors.initials: L
authors.lastname: DeSoto
authors.affiliation: Laboratorio de Botánica, EUI Agrarias de Soria, Universidad de Valladolid, Los Pajaritos s/n, 42004 Soria, Spain.
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Olano
mesh_terms: D000704:Analysis of Variance; D002980:Climate; D018653:Juniperus / Q000254:growth & development*; D011891:Rain; D012044:Regression Analysis; D012621:Seasons; D013030:Spain; D013696:Temperature; D013997:Time Factors; D014197:Trees / Q000254:growth & development*