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San Sebastián de los Reyes, Spain

Camarero J.J.,CSIC - Pyrenean Institute of Ecology | Olano J.M.,Area de Biologia Vegetal | Parras A.,CSIC - Pyrenean Institute of Ecology
New Phytologist | Year: 2010

Seasonal radial-increment and xylogenesis data can help to elucidate how climate modulates wood formation in conifers. Few xylogenesis studies have assessed how plastic xylogenesis is in sympatric conifer species from continental Mediterranean areas, where low winter temperatures and summer drought constrain growth. Here, we analysed intra-annual patterns of secondary growth in sympatric conifer species (Juniperus thurifera, Pinus halepensis and Pinus sylvestris). Two field sites (xeric and mesic) were evaluated using dendrometers, microcores and climatic data. A bimodal pattern of xylogenesis characterized by spring and autumn precipitation and subsequent cambial reactivation was detected in J. thurifera at both study sites and in P. halepensis at the xeric site, but was absent in P. sylvestris where growth was largely controlled by day length. In the xeric site J. thurifera exhibited an increased response to water availability in autumn relative to P. halepensis and summer cambial suppression was more marked in J. thurifera than in P. halepensis. Juniperus thurifera exhibited increased plasticity in its xylogenesis pattern compared with sympatric pines, enabling this species to occupy sites with more variable climatic conditions. The plastic xylogenesis patterns of junipers in drought-stressed areas may also provide them with a competitive advantage against co-occurring pines. © 2009 New Phytologist. Source

Camarero J.J.,CSIC - Pyrenean Institute of Ecology | Olano J.M.,Area de Biologia Vegetal | Arroyo Alfaro S.J.,University of the Basque Country | Fernandez-Marin B.,University of the Basque Country | And 2 more authors.
Flora: Morphology, Distribution, Functional Ecology of Plants | Year: 2012

Acclimation to local conditions may produce adaptive responses in plants subjected to diverse climatic stresses. However, it has not been assessed how local adaptation and phenotypic plasticity contribute to photoprotection mechanisms in response to contrasting climatic conditions in Mediterranean tree species.We analyzed photoprotection mechanisms in mature trees of the Mediterranean evergreen oak Quercus ilex at three sites with contrasting climatic conditions, i.e. xeric, continental and mesic sites. We studied morphological and physiological parameters indicative of photoprotection in adult trees in the field. In order to establish whether these parameters were genetically determined we compared adults with seedlings germinated from acorns of the three sites and grown under common greenhouse conditions.In the field we found no significant differences in most of the physiological parameters in summer, but in winter the adult trees from the continental site were photoinhibited. In contrast, there were significant differences between seedlings in most photoprotective parameters evaluated. Morphological traits such as trichome density and leaf reflectance differed between populations, both in field-grown trees and in greenhouse-grown seedlings, being higher in all cases in plants from the xeric site than elsewhere. Our findings suggest the existence of constitutive differences in leaf photoprotection mechanisms among Q. ilex populations. These divergences may represent an inherent source for more stress tolerant ecotypes in the face of changing climatic conditions. © 2012 Elsevier GmbH. Source

Barrutia O.,University of the Basque Country | Artetxe U.,University of the Basque Country | Hernandez A.,University of the Basque Country | Olano J.M.,Area de Biologia Vegetal | And 3 more authors.
International Journal of Phytoremediation | Year: 2011

Plants growing on metalliferous soils from abandoned mines are unique because of their ability to cope with high metal levels in soil. In this study, we characterized plants and soils from an abandoned Pb-Zn mine in the Basque Country (northern Spain). Soil in this area proved to be deficient in major macronutrients and to contain toxic levels of Cd, Pb, and Zn. Spontaneously growing native plants (belonging to 31 species, 28 genera, and 15 families) were botanically identified. Plant shoots and rhizosphere soil were sampled at several sites in themine, and analyzed for Pb, Zn and Cd concentration. Zinc showed the highest concentrations in shoots, followed by Pb and Cd.Highest Zn concentrations in shoots were found in the Zn-Cd hyperaccumulator Thlaspi caerulescens (mean = 18,254 mg Zn kg-1 DW). Different metal tolerance and accumulation patterns were observed among the studied plant species, thus offering a wide germplasm assortment for the suitable selection of phytoremediation technologies. This study highlights the importance of preserving metalliferous environments as they shelter a unique and highly valuable metallicolous biodiversity. © Taylor & Francis Group, LLC. Source

Garcia-Cervigon Morales A.I.,Area de Biologia Vegetal | Olano Mendoza J.M.,Area de Biologia Vegetal | Eugenio Gozalbo M.,Area de Biologia Vegetal | Camarero Martinez J.J.,CSIC - Pyrenean Institute of Ecology
Dendrochronologia | Year: 2012

In contrast to most high elevation areas, plant growth at Mediterranean mountains is exposed to a summer drought period, which represents an additional climatic constraint to low temperatures. Although arboreal and shrubby conifers coexist at high altitudes, most dendroecological studies have focused on climatic responses of tree species, whereas those of shrubby species remain mostly unexplored. We built tree-ring width chronologies for two conifer species, a shrub (Juniperus sabina) and a tree (Pinus sylvestris), coexisting at three high-altitude localities of the Iberian System mountains, eastern Spain. We analyzed their climate-growth relationships for the period 1950-2009 using correlation analyses and multiple regressions. Coexisting species responded to year-to-year climatic variability in different ways. Radial growth in junipers and pines responded positively to April and May temperatures, respectively. Summer drought constrained growth in both cases, although its impact was stronger on junipers than on pines. Our findings suggest that junipers respond earlier than pines to spring temperatures due to their prostrate morphology which may enhance a fast warming of their cambial meristems after snowmelt. The higher dependence of . J. sabina on summer rainfall as compared with co-occurring pines confirms that drought stress negatively impacts secondary growth in Mediterranean mountains. This sensitivity to water availability may be caused by the juniper shallow root systems, which mainly use superficial soil water. The climatic signal registered in . J. sabina allows studying the response of other similar shrubby woody species growing in Mediterranean alpine areas to the ongoing climate warming, which could also reduce water availability. © 2012 Elsevier GmbH. Source

Garcia-Cervigon A.I.,Area de Biologia Vegetal | Gazol A.,University of Tartu | Sanz V.,Area de Biologia Vegetal | Camarero J.J.,CSIC - Pyrenean Institute of Ecology | And 2 more authors.
Perspectives in Plant Ecology, Evolution and Systematics | Year: 2013

Plant-plant interactions change depending on environmental conditions, shifting from competition to facilitation when the stress is high. In addition to these changes, the relevance of intraspecific compared to interspecific interactions may also shift as abiotic stress does. We inferred intra- and interspecific plant-plant interactions of the cushion plant Hormathophylla spinosa as related to the dominant shrub Juniperus sabina in two sites with contrasting abiotic conditions (a slope with high-stress conditions vs. a valley bottom with milder conditions) in a Mediterranean high mountain. Specifically, we studied the spatial patterns and several variables related to plant performance (plant size and form, non-structural carbohydrate - NSC - concentrations and radial growth) of H. spinosa.The spatial pattern varied depending on site conditions. H. spinosa plants were positively associated with juniper in the high-stress slope site, probably through higher establishment rates due to the amelioration of soil conditions. In contrast, in the milder valley site H. spinosa establishment occurred mostly in open areas. Age structure, inferred from annual rings, reflected a massive establishment event in the whole study area which occurred 30-50 years ago. Canopy variables and radial growth were density dependent: both were negatively affected by the high density of H. spinosa individuals in the valley, but favoured by junipers on the slope. Interestingly, NSCs showed the opposite pattern, suggesting lower investment in growth by H. spinosa plants in the valley than on the slope.Our results reinforce the strong links existing between intra- and interspecific relationships and the need to include both when studying the influence of abiotic conditions on plant-plant interactions. This approach enabled us to detect that the direction and intensity of plant-plant interactions may shift at different ecological levels. Particularly interesting was the finding that optimal sites at the population level may not necessarily be the sites showing maximum individual performance. © 2013 Perspectives in Plant Ecology, Evolution and Systematics. Source

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