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Publications (4)6.25 Total impact

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    ABSTRACT: Long-term data on radial increment dynamics in Mediterranean species may identify which climatic variables are the main constraints for radial growth and at which temporal scales they act. To this end, we examined stem radial fluctuations in Quercus ilex L., the dominant evergreen oak species in the Western Mediterranean Basin, over a period of 11years (1994–2004) at a coastal site in north-eastern Spain. We used manual band dendrometers to record girth changes in trees on north- and south-facing slopes. Annual increments measured by dendrometers showed good agreement with annual tree-ring width. North-facing trees showed a lower long-term cumulative radial increment than south-facing trees. The seasonal radial increment pattern of Q. ilex was bimodal, being characterized by a greater increase in May and a lesser, more variable increase peak in September. Both phases corresponded to warm and moist climatic conditions, whereas radial increase of stems stopped in winter and occasionally in summer. Considering the whole year, mean maximum air temperature was the main factor positively affecting radial increment of Q. ilex from short- (5days) to- long (30days) time scales, whereas the accumulated precipitation exerted a similar effect at longer (30days) scales, but only on south-facing trees. In summer, all trees were positively correlated with precipitation at long-time scales (30days); however, only stem increment of south-facing trees showed a significant relation to the temperature at short-time scales (10days). We confirmed the dominant role of temperature as the major constraint on radial increment at short time scales, despite most previous studies were mostly biased towards precipitation effects at monthly scales. KeywordsBand dendrometer–Drought–Mediterranean climate–Bimodal growth–Holm oak
    Trees 01/2011; 25(4):637-646. · 1.93 Impact Factor
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    ABSTRACT: Wildfires have decimated forests of Pinus nigra in the Mediterranean Basin in recent decades, but little is known about the fire ecology of this native species. We sampled three small relict forest sites on Sierra Turmell, Castellón, Valencia, northeastern Spain, to determine forest structure and past fire events. The forest was characterized by relatively large and old trees (mean 158 year, max 362 year). Fire history was affected by obliteration of some fire scars, but we determined 11 fire dates in the past 172 years. The minimum fire-free interval was 2 years, maximum 57 years. Fire dates were not linked with dry climatic conditions, possibly due to occupational burning by pastoralists. Compared to inventory data averages for P. nigra in northeastern Spain (Catalunya), the old forest at Sierra Turmell supported over twice the basal area and over 2.5 times the biomass, with a comparable advantage in terms of carbon storage. Carbon sequestration, on the other hand, was over six times higher in the younger forests. The relict forest at Sierra Turmell provides evidence of multi-aged forest structure persisting through numerous surface fires over several centuries. This example may be useful for guiding management of younger forests and for ecological restoration of degraded areas.
    Forest Ecology and Management 03/2008; 255(3-4):1234–1242. · 2.77 Impact Factor
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    ABSTRACT: The influence of climatic factors on tree-ring width and the formation of double rings was studied in Quercus ilex L. growing in a coppice stand left unmanaged for 22 years. Ten trees were felled and discs were taken every 30 cm from bole and dominant branches. Dendrometer bands were installed on 10 nearby trees and the data recorded were used to confirm the accuracy of our tree-ring identification. They were also used to relate the seasonal radial growth pattern to double-ring formation. Double rings were frequent and occurred consistently along the stem. Two types of double rings could be recognized according to their width: type I, with the extra growth band accounting for approximately 50% of the tree ring; and type II, with a narrow extra growth band. Type I double rings were formed when approximately 1/2 of the growing-season precipitation occurred during the second growth period of the season and after the summer drought. Type II double rings occurred when approximately 1/3 of the precipitation in the growing season occurred after the summer drought. The formation of double rings was triggered by rainfall in summer and the extra growth-band width was related to summer and autumn environmental conditions. Double rings in Q. ilex can potentially be used in dendroclimatological studies, as they are formed in response to climatic conditions within the growing season. Résumé : L'influence des facteurs climatiques sur la largeur des cernes annuels et la formation des cernes annuels doubles ont été étudiés chez Quercus ilex L. croissant en taillis non aménagé depuis 22 ans. Dix arbres ont été abattus et des ron-delles ont été prélevées à tous les 30 cm sur le tronc et les branches principales. Des bandes-verniers ont été installées sur 10 arbres voisins et les données enregistrées par ces bandes ont été utilisées pour confirmer la justesse de notre identifica-tion des cernes annuels. Elles ont aussi été utilisées pour relier le patron saisonnier de croissance radiale avec la formation de cernes annuels doubles. Les cernes annuels doubles étaient fréquents et apparaissaient régulièrement le long du tronc. Deux types de cernes annuels doubles pouvaient être identifiés selon leur largeur : le type I, dont la bande de croissance additionnelle représente environ 50 % du cerne annuel et le type II, caractérisé par une étroite bande de croissance addi-tionnelle. Les cernes doubles de type I étaient formés lorsque environ 1/2 des précipitations de la saison de croissance sur-venait durant la seconde période de croissance et après la sécheresse estivale. Les cernes doubles de type II apparaissaient lorsque environ 1/3 des précipitations de la saison de croissance survenait après la sécheresse estivale. La formation de cernes annuels doubles était déclenchée par les précipitations estivales et la largeur de la bande de croissance additionnelle était reliée aux conditions environnementales durant l'été et l'automne. Les cernes annuels doubles chez Q. ilex pourraient possiblement être utilisés dans des études dendroclimatologiques puisqu'ils sont formés en réponse aux conditions clima-tiques durant la saison de croissance. [Traduit par la Rédaction]
    Canadian Journal of Forest Research 01/2007; 37:1915-1923. · 1.56 Impact Factor
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    Montserrat Ribas, Elena Muntán, Emilia Gutiérrez
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    ABSTRACT: Radial growth response of Aleppo pine (Pinus halepensis Mill.) to climatic conditions