Impacts of global change on Mediterranean forests and their services

Peñuelas, J., Sardans, J., Filella, I., Estiarte, M., Llusià, J., Ogaya, R., Carnicer, J., Bartrons, M., Rivas-Ubach, A., Grau, O., Peguero, G., Margalef, O., Pla-Rabés, S., Stefanescu, C., Asensio, D., Preece, C., Liu, L., Verger, A., Barbeta, A., Achotegui-Castells, A., Gargallo-Garriga, A., Sperlich, D., Farré-Armengol, G., Fernández-Martínez, M., Liu, D., Zhang, C., Urbina, I., Camino-Serrano, M., Vives-Ingla, M., Stocker, B.D., Balzarolo, M., Guerrieri, R., Peaucelle, M., Marañón-Jiménez, S., Bórnez-Mejías, K., Mu, Z., Descals, A., Castellanos, A., Terradas, J. (2017) Impacts of global change on Mediterranean forests and their services. Forests. 8: 0-0.
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Doi: 10.3390/f8120463

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Assessment of the impacts of climate change on Mediterranean terrestrial ecosystems based on data from field experiments and long-term monitored field gradients in Catalonia

Peñuelas, J., Sardans, J., Filella, I., Estiarte, M., Llusià, J., Ogaya, R., Carnicer, J., Bartrons, M., Rivas-Ubach, A., Grau, O., Peguero, G., Margalef, O., Pla-Rabés, S., Stefanescu, C., Asensio, D., Preece, C., Liu, L., Verger, A., Rico, L., Barbeta, A., Achotegui-Castells, A., Gargallo-Garriga, A., Sperlich, D., Farré-Armengol, G., Fernández-Martínez, M., Liu, D., Zhang, C., Urbina, I., Camino, M., Vives, M., Nadal-Sala, D., Sabaté, S., Gracia, C., Terradas, J. (2016) Assessment of the impacts of climate change on Mediterranean terrestrial ecosystems based on data from field experiments and long-term monitored field gradients in Catalonia. Environmental and Experimental Botany. : 0-0.
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Doi: 10.1016/j.envexpbot.2017.05.012

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Spatial variability and controls over biomass stocks, carbon fluxes, and resource-use efficiencies across forest ecosystems

Fernandez-Martinez M., Vicca S., Janssens I.A., Luyssaert S., Campioli M., Sardans J., Estiarte M., Penuelas J. (2014) Spatial variability and controls over biomass stocks, carbon fluxes, and resource-use efficiencies across forest ecosystems. Trees - Structure and Function. 28: 597-611.
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Doi: 10.1007/s00468-013-0975-9

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Key message: Stand age, water availability, and the length of the warm period are the most influencing controls of forest structure, functioning, and efficiency. We aimed to discern the distribution and controls of plant biomass, carbon fluxes, and resource-use efficiencies of forest ecosystems ranging from boreal to tropical forests. We analysed a global forest database containing estimates of stand biomass and carbon fluxes (400 and 111 sites, respectively) from which we calculated resource-use efficiencies (biomass production, carbon sequestration, light, and water-use efficiencies). We used the WorldClim climatic database and remote-sensing data derived from the Moderate Resolution Imaging Spectroradiometer to analyse climatic controls of ecosystem functioning. The influences of forest type, stand age, management, and nitrogen deposition were also explored. Tropical forests exhibited the largest gross carbon fluxes (photosynthesis and ecosystem respiration), but rather low net ecosystem production, which peaks in temperate forests. Stand age, water availability, and length of the warm period were the main factors controlling forest structure (biomass) and functionality (carbon fluxes and efficiencies). The interaction between temperature and precipitation was the main climatic driver of gross primary production and ecosystem respiration. The mean resource-use efficiency varied little among biomes. The spatial variability of biomass stocks and their distribution among ecosystem compartments were strongly correlated with the variability in carbon fluxes, and both were strongly controlled by climate (water availability, temperature) and stand characteristics (age, type of leaf). Gross primary production and ecosystem respiration were strongly correlated with mean annual temperature and precipitation only when precipitation and temperature were not limiting factors. Finally, our results suggest a global convergence in mean resource-use efficiencies. © 2013 Springer-Verlag Berlin Heidelberg.

Llegeix més

A tethered-balloon PTRMS sampling approach for surveying of landscape-scale biogenic VOC fluxes

Greenberg J.P., Penuelas J., Guenther A., Seco R., Turnipseed A., Jiang X., Filella I., Estiarte M., Sardans J., Ogaya R., Llusia J., Rapparini F. (2014) A tethered-balloon PTRMS sampling approach for surveying of landscape-scale biogenic VOC fluxes. Atmospheric Measurement Techniques. 7: 2263-2271.
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Doi: 10.5194/amt-7-2263-2014

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Landscape-scale fluxes of biogenic gases were surveyed by deploying a 100 m Teflon tube attached to a tethered balloon as a sampling inlet for a fast-response proton-transfer-reaction mass spectrometer (PTRMS). Along with meteorological instruments deployed on the tethered balloon and a 3 m tripod and outputs from a regional weather model, these observations were used to estimate landscape-scale biogenic volatile organic compound fluxes with two micrometeorological techniques: mixed layer variance and surface layer gradients. This highly mobile sampling system was deployed at four field sites near Barcelona to estimate landscape-scale biogenic volatile organic compound (BVOC) emission factors in a relatively short period (3 weeks). The two micrometeorological techniques were compared with emissions predicted with a biogenic emission model using site-specific emission factors and land-cover characteristics for all four sites. The methods agreed within the uncertainty of the techniques in most cases, even though the locations had considerable heterogeneity in species distribution and complex terrain. Considering the wide range in reported BVOC emission factors for individual vegetation species (more than an order of magnitude), this temporally short and inexpensive flux estimation technique may be useful for constraining BVOC emission factors used as model inputs. © 2014 Author(s).

Llegeix més

Intensive measurements of gas, water, and energy exchange between vegetation and troposphere during the MONTES campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean Basin

Penuelas J., Guenther A., Rapparini F., Llusia J., Filella I., Seco R., Estiarte M., Mejia-Chang M., Ogaya R., Ibanez J., Sardans J., Castano L.M., Turnipseed A., Duhl T., Harley P., Vila J., Estavillo J.M., Menendez S., Facini O., Baraldi R., Geron C., Mak J., Patton E.G., Jiang X., Greenberg J. (2013) Intensive measurements of gas, water, and energy exchange between vegetation and troposphere during the MONTES campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean Basin. Atmospheric Environment. 75: 348-364.
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Doi: 10.1016/j.atmosenv.2013.04.032

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MONTES ("Woodlands") was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Western Mediterranean Basin (WMB). The measurements were performed at a semidesertic area (Monegros), at a coastal Mediterranean shrubland area (Garraf), at a typical Mediterranean holm oak forest area (Prades) and at a wet temperate beech forest (Montseny) during spring (April 2010) under optimal plant physiological conditions in driest-warmest sites and during summer (July 2010) with drought and heat stresses in the driest-warmest sites and optimal conditions in the wettest-coolest site. The objective of this campaign was to study the differences in gas, water and energy exchange occurring at different vegetation coverages and biomasses. Particular attention was devoted to quantitatively understand the exchange of biogenic volatile organic compounds (BVOCs) because of their biological and environmental effects in the WMB. A wide range of instruments (GC-MS, PTR-MS, meteorological sensors, O3 monitors,. .) and vertical platforms such as masts, tethered balloons and aircraft were used to characterize the gas, water and energy exchange at increasing footprint areas by measuring vertical profiles. In this paper we provide an overview of the MONTES campaign: the objectives, the characterization of the biomass and gas, water and energy exchange in the 4 sites-areas using satellite data, the estimation of isoprene and monoterpene emissions using MEGAN model, the measurements performed and the first results. The isoprene and monoterpene emission rates estimated with MEGAN and emission factors measured at the foliar level for the dominant species ranged from about 0 to 0.2mgm-2h-1 in April. The warmer temperature in July resulted in higher model estimates from about 0 to ca. 1.6mgm-2h-1 for isoprene and ca. 4.5mgm-2h-1 for monoterpenes, depending on the site vegetation and footprint area considered. There were clear daily and seasonal patterns with higher emission rates and mixing ratios at midday and summer relative to early morning and early spring. There was a significant trend in CO2 fixation (from 1 to 10mgCm-2d-1), transpiration (from1-5kgCm-2d-1), and sensible and latent heat from the warmest-driest to the coolest-wettest site. The results showed the strong land-cover-specific influence on emissions of BVOCs, gas, energy and water exchange, and therefore demonstrate the potential for feed-back to atmospheric chemistry and climate. •We present a multidisciplinary biosphere-atmosphere field campaign.•We measured a gradient from semi-desertic shrublands to wet temperate forests.•A wide range of instruments and vertical platforms were used.•Land cover strongly influenced emissions of BVOCs and gas, energy and water exchange.•Vegetation has strong potential for feed-back to atmospheric chemistry and climate. © 2013 Elsevier Ltd.

Llegeix més

Evidence of current impact of climate change on life: A walk from genes to the biosphere

Penuelas J., Sardans J., Estiarte M., Ogaya R., Carnicer J., Coll M., Barbeta A., Rivas-Ubach A., Llusia J., Garbulsky M., Filella I., Jump A.S. (2013) Evidence of current impact of climate change on life: A walk from genes to the biosphere. Global Change Biology. 19: 2303-2338.
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Doi: 10.1111/gcb.12143

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We review the evidence of how organisms and populations are currently responding to climate change through phenotypic plasticity, genotypic evolution, changes in distribution and, in some cases, local extinction. Organisms alter their gene expression and metabolism to increase the concentrations of several antistress compounds and to change their physiology, phenology, growth and reproduction in response to climate change. Rapid adaptation and microevolution occur at the population level. Together with these phenotypic and genotypic adaptations, the movement of organisms and the turnover of populations can lead to migration toward habitats with better conditions unless hindered by barriers. Both migration and local extinction of populations have occurred. However, many unknowns for all these processes remain. The roles of phenotypic plasticity and genotypic evolution and their possible trade-offs and links with population structure warrant further research. The application of omic techniques to ecological studies will greatly favor this research. It remains poorly understood how climate change will result in asymmetrical responses of species and how it will interact with other increasing global impacts, such as N eutrophication, changes in environmental N : P ratios and species invasion, among many others. The biogeochemical and biophysical feedbacks on climate of all these changes in vegetation are also poorly understood. We here review the evidence of responses to climate change and discuss the perspectives for increasing our knowledge of the interactions between climate change and life. © 2013 John Wiley & Sons Ltd.

Llegeix més

Field-simulated droughts affect elemental leaf stoichiometry in Mediterranean forests and shrublands

Sardans J., Rivas-Ubach A., Estiarte M., Ogaya R., Penuelas J. (2013) Field-simulated droughts affect elemental leaf stoichiometry in Mediterranean forests and shrublands. Acta Oecologica. 50: 20-31.
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Doi: 10.1016/j.actao.2013.04.002

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This study evaluated the change induced by the year season and by experimentally induced drought on foliar element stoichiometry of the predominant woody species (. Quercus ilex and Erica multiflora) in two Mediterranean ecosystems, a forest and a shrubland. This study is based in two long-term (11yr) field experiments that simulated drought throughout the annual cycle.The effects of experimental droughts were significant but weaker than the changes produced by ontogeny and seasonality. Leaf N and P concentrations were higher in spring (the main growing season) in E. multiflora and, in Q.ilex in autumn (a period of additional growth). Leaf N:P ratios were lower in spring. In Q.ilex, the highest leaf K concentrations and leaf K:P ratios, and the lowest leaf C:K and N:K ratios, occurred in summer, the season when water stress was greatest. In E.multiflora, leaf K concentrations and K:P ratios were highest, and leaf C:K and N:K ratios were lowest in the plants from the drought-treated plots.The plant capacity to change K concentrations in response to seasonality and to drought is at least as great as the capacity to change N and P concentrations. The results underscore the importance of K and its stoichiometry relative to C, N and P in dry environments. These results indicate first, that N:P ratio shifts are not uniquely related to growth rate in Mediterranean plants but also to drought, and second, that there is a need to take into account K in ecological stoichiometry studies of terrestrial plants. © 2013 Elsevier Masson SAS.

Llegeix més

Una nova ciència per entendre els ecosistemes: l'ecometabolòmica.

Rivas-Ubach A, Sardans J, Pérez-Trujillo M, Estiarte M, Peñuelas J (2012) Una nova ciència per entendre els ecosistemes: l'ecometabolòmica. Omnis Cellula 28: 5.

Strong relationship between elemental stoichiometry and metabolome in plants

Rivas-Ubach A, Sardans J, Pérez-Trujillo M, Estiarte M, Peñuelas J (2012) Strong relationship between elemental stoichiometry and metabolome in plants. Proceedings of the National Academy of Sciencies 109: 4181-4186.

Second report on climate change in Catalonia

Llebot JE, Carnicer J, Curiel J, Coll M, Díaz de Quijano M, Estiarte M, Filella I, Garbulsky M, Jump A, Llusià J, Ogaya R, Peñuelas J, Rico L, Rivas-Ubach A, Rutishauser T, Sardans J, Seco R, Silva J, Stefanescu C, Terradas J (2012) Second report on climate change in Catalonia. Executive summary. Institut d'Estudis Catalans. Generalitat de Catalunya. pp. 1-36. ISBN9788499650975.

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