Poyatos R., Aguade D., Galiano L., Mencuccini M., Martinez-Vilalta J. (2013) Drought-induced defoliation and long periods of near-zero gas exchange play a key role in accentuating metabolic decline of Scots pine. New Phytologist. 200: 388-401.EnlaceDoi: 10.1111/nph.12278
Summary: Drought-induced defoliation has recently been associated with the depletion of carbon reserves and increased mortality risk in Scots pine (Pinus sylvestris). We hypothesize that defoliated individuals are more sensitive to drought, implying that potentially higher gas exchange (per unit of leaf area) during wet periods may not compensate for their reduced photosynthetic area. We measured sap flow, needle water potentials and whole-tree hydraulic conductance to analyse the drought responses of co-occurring defoliated and nondefoliated Scots pines in northeast Spain during typical (2010) and extreme (2011) drought conditions. Defoliated Scots pines showed higher sap flow per unit leaf area during spring, but were more sensitive to summer drought, relative to nondefoliated pines. This pattern was associated with a steeper decline in soil-to-leaf hydraulic conductance with drought and an enhanced sensitivity of canopy conductance to soil water availability. Near-homeostasis in midday water potentials was observed across years and defoliation classes, with minimum values of -2.5 MPa. Enhanced sensitivity to drought and prolonged periods of near-zero gas exchange were consistent with low levels of carbohydrate reserves in defoliated trees. Our results support the critical links between defoliation, water and carbon availability, and their key roles in determining tree survival and recovery under drought. © 2013 New Phytologist Trust.
Arnan X., López B.C., Martínez-Vilalta J., Estorach M., Poyatos R. (2012) The age of monumental olive trees (Olea europaea) in northeastern Spain. Dendrochronologia. 30: 11-14.EnlaceDoi: 10.1016/j.dendro.2011.02.002
Trees can reach ages that in some cases amount to thousands of years. In the Mediterranean region, olive trees (Olea europaea) have traditionally been considered a particularly long-lived species. The main objective of this study was to assess the age of large olive trees considered to be millenarian and classified as monumental trees in northeastern Spain. We extracted cores of 14 individuals and obtained 8 sections of trees which had already been cut in the area where the largest olive trees in the northeastern Iberian Peninsula are found. The age of the sampled olive trees was assessed by counting the number of annual growth rings. Tree rings did not cross-date well, neither within nor between individuals, but boundaries between likely annual rings were clearly distinct. We found a linear relationship between DBH and tree age (in years) (Age=2.11×diameter(cm)+88.93, R2=0.80), which was used to estimate the age of unsampled olive trees. The maximum estimated age (627±110 years) is among the greatest ages reported for olive trees around the world (700 years) and among the oldest trees in Mediterranean ecosystems. © 2011 Istituto Italiano di Dendrocronologia.
Martínez-Vilalta J, Aguadé D, Banqué M, Barba J, Curiel Yuste J, Galiano L, Garcia N, Gómez M, Heres; AM, López BC, Lloret F, Poyatos R, Retana J, Sus O, Vayreda J, Vilà-Cabrera A (2012) Las poblaciones ibéricas de pino albar ante el cambio climático: con la muerte en los talones. Ecosistemas 21: 15-21.
Martínez-Vilalta J, Aguadé D, Banqué M, Barba J, Yuste JC, Galiano L, Garcia N, Gómez M, Hereş AM, López BC, Lloret F, Poyatos R, Retana J, Sus O, Vayreda J, Vilà-Cabrera A (2012) Las poblaciones ibéricas de pino albar ante el cambio climático: con la muerte en los talones. Revista Ecosistemas 21: 15–21.
Sus O, Martínez-Vilalta J, Poyatos R, Williams M (2012) Constraining key hydraulic parameters of Scots pine through sapﬂow data assimilation along a climatic gradient. Geophysical Research Abstracts 14: 10170. EGU General Assembly 2012,Vienna (Austria), 22-27 Abril 2012. Póster.
Sus O, Martinez-Vilalta J, Poyatos R, Williams M (2012) Constraining key hydraulic parameters of Scots Pine through sapflow data assimilation along a climatic gradient. EGU Annual Meeting, Vienna, Austria, 22-27 April 2012. (Pòster).
Rubio CM, Poyatos R (2012) Applicability of Hydrus-1D in a Mediterranean Mountain Area Submitted to Land Use Changes. ISRN Soil Science 1–7.
Poyatos R, Aguadé D, Galiano L, Martínez-Vilalta J (2012) Defoliación inducida por sequía y límites hidráulicos a la asimilación asociados al agotamiento de carbohidratos de reserva en pino albar. II Coloquio de Primavera de Ecofisiología Forestal, Binifaldó (Mallorca), 19-23 Junio 2012.Comunicación oral.
Poyatos R, Gornall J, Mencuccini M, Huntley B, Baxter R (2012) Seasonal controls on net branch CO2 assimilation in sub-Arctic Mountain Birch (Betula pubescens ssp. czerepanovii (Orlova) Hamet-Ahti). Agricultural and Forest Meteorology 158: 90-100.
Sterck F.J., Martínez-Vilalta J., Mencuccini M., Cochard H., Gerrits P., Zweifel R., Herrero A., Korhonen J.F., Llorens P., Nikinmaa E., Nolè A., Poyatos R., Ripullone F., Sass-Klaassen U. (2012) Understanding trait interactions and their impacts on growth in Scots pine branches across Europe. Functional Ecology. 26: 541-549.EnlaceDoi: 10.1111/j.1365-2435.2012.01963.x
Plants exhibit a wide variety in traits at different organizational levels. Intraspecific and interspecific studies have potential to demonstrate functional relationships and trade-offs amongst traits, with potential consequences for growth. However, the distinction between the correlative and functional nature of trait covariation presents a challenge because traits interact in complex ways. We present an intraspecific study on Scots pine branches and use functional multi-trait concepts to organize and understand trait interactions and their impacts on growth. Branch-level traits were assessed for 97 branches from 12 Scots pine sites across Europe. To test alternative hypotheses on cause-effect relationships between anatomical traits, hydraulic traits and branch growth, we measured for each branch: the tracheid hydraulic diameter, double cell wall thickness, cell lumen span area, wood density, cavitation vulnerability, wood-specific hydraulic conductivity, the leaf area to sapwood area ratio and branch growth. We used mixed linear effect models and path models to show how anatomical traits determine hydraulic traits and, in turn, how those traits influence growth. Tracheid hydraulic diameter was the best predictor of cavitation vulnerability (R 2=0·09 explained by path model) and specific conductivity (R 2=0·19) amongst anatomical traits. Leaf area to sapwood area ratio had the strongest direct effect on branch growth (R 2=0·19) and was positively associated with the tracheid hydraulic diameter (R 2=0·22). A number of bivariate correlations between traits could be explained by these functional relationships amongst traits. The plasticity in tracheid hydraulic diameter (10.0-15.1μm) and leaf area to sapwood area ratio (600-6051cm 2cm -2) and the maintenance of a minimum leaf water potential (between -2 and -2·5MPa) appear to drive the anatomical and hydraulic traits of Scots pine across Europe. These properties are major drivers of the functional trait network underlying the growth variation amongst pine branches and thus possibly contribute to the ecological success of pines at a local and continental scale. © 2012 The Authors. Functional Ecology © 2012 British Ecological Society.
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