Research Interests: Botany, Climate Change, Photosynthesis, Plant Biology, Biology, and 15 moreDensity, Competitive advantage, Biological Sciences, Environmental Sciences, Chlorophyll Fluorescence, Forests, Light, Leaf Nitrogen, Dynamic Response, North East, Photosystem II, Photosynthetic Rate, Biochemistry and cell biology, Leaf Gas Exchange, and Leaf Temperature
Research Interests: Environmental Science, Climate Change, Climate variability, Biology, Biological Sciences, and 13 moreEnvironmental Sciences, Soil moisture, Ecosystems, Water balance, Greenhouse Gas Emissions, Temperature measurement, Ecosystem, Infrared Radiation, Early Terrestrial Ecosystems, Wind Speed, Terrestrial Ecosystem, Heat Loss, and Heat Balance
Abstract Models predict an increase in solar ultraviolet (UV) radiation, a decrease in precipitation and a higher frequency of disturbances (e.g. fires) in the near future in the Mediterranean basin. Thus, this study examined the effects... more
Abstract Models predict an increase in solar ultraviolet (UV) radiation, a decrease in precipitation and a higher frequency of disturbances (e.g. fires) in the near future in the Mediterranean basin. Thus, this study examined the effects of enhanced UV radiation (UV-A and UV-B) and diminished water supply on leaf morphology and physiology, plant growth, root reserves and resprouting capacity of two common Mediterranean species, before and after aerial biomass removal (simulating a disturbance, such as a severe fire). An outdoor experiment was conducted growing potted seedlings of strawberry tree (Arbutus unedo) and cork oak (Quercus suber) with enhanced UV-A + UV-B, enhanced UV-A or ambient UV, combined with optimal or reduced watering. Eight months after the start of the experiment, all the plant aerial biomass was removed and new shoots (resprouts) developed for a further 8 months under the UV and watering treatments. For both species, the responsiveness of seedlings (pre-disturbance) and resprouting plants (post-disturbance) to the treatments differed. Enhanced UV-B reduced the leaf relative water content (RWC) in well-watered A. unedo plants (seedlings and resprouts), decreasing also the amount of root phenols in well-watered resprouts of this species. In parallel, however, exposure to enhanced UV-B increased the photosynthetic rates of A. unedo resprouts, regardless of the irrigation level. Seedlings and resprouts of Q. suber responded to enhanced UV-A by hardening the leaves (increased leaf mass per area, LMA), although UV-A-supplemented seedlings allocated less carbon to produce leaves in relation to roots. Most UV effects were found only under optimal irrigation, suggesting a decrease in plant UV sensitivity under low water availability. In Q. suber, water shortage per se reduced leaf:total biomass and the concentration of sugar in roots. Despite some UV and watering effects on the parameters studied, the protective mechanisms displayed by both species were apparently effective since root starch reserves and plant resprouting capacity were not reduced by the treatments.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
During the Mesozoic, the polar regions supported coniferous forests that experienced warm climates, a CO(2)-rich atmosphere and extreme seasonal variations in daylight. How the interaction between the last two factors might have... more
During the Mesozoic, the polar regions supported coniferous forests that experienced warm climates, a CO(2)-rich atmosphere and extreme seasonal variations in daylight. How the interaction between the last two factors might have influenced water use of these conifers was investigated. An experimental approach was used to test the following hypotheses: (1) the expected beneficial effects of elevated [CO(2)] on water-use efficiency (WUE) are reduced or lost during the 24-h light of the high-latitude summer; and (2) elevated [CO(2)] reduces plant water use over the growing season. Measurements of leaf and whole-plant gas exchange, and leaf-stable carbon isotope composition were made on one evergreen (Sequoia sempervirens) and two deciduous (Metasequoia glyptostroboides and Taxodium distichum) 'living fossil' coniferous species after 3 years' growth in controlled-environment simulated Cretaceous Arctic (69 degrees N) conditions at either ambient (400 micromol mol(-1)) or ele...
Research Interests:
Climate projections predict drier and warmer conditions in the Mediterranean basin in the next decades. The possibility of such climatic changes modifying the growth of two Mediterranean species, Erica multiflora and Globularia alypum,... more
Climate projections predict drier and warmer conditions in the Mediterranean basin in the next decades. The possibility of such climatic changes modifying the growth of two Mediterranean species, Erica multiflora and Globularia alypum, which are common components of Mediterranean shrublands, was assessed. A field experiment was performed from March 1999 to March 2002 to prolong the drought period and to increase the night-time temperature in a Mediterranean shrubland, where E. multiflora and G. alypum are the dominant species. Annual growth in stem diameter and length of both species was measured and annual stem biomass production was estimated for 1999, 2000 and 2001. Plant seasonal growth was also assessed. On average, drought treatment reduced soil moisture 22 %, and warming increased temperature by 0.7-1.6 degrees C. Erica multiflora plants in the drought treatment showed a 46 % lower annual stem elongation than controls. The decrease in water availability also reduced by 31 % t...
Research Interests: Climate Change, Water, Plant Biology, Water Availability, Ecology, and 15 moreSeasonality, Soil moisture, Circadian Rhythm, Field Experiment, Rain, Species Composition, Biomass production, Ericaceae, Mediterranean region, Seasons, Species Specificity, Mediterranean Basin, Assessment Methods, Scrophulariaceae, and Growth pattern
Research Interests:
De UvA-LINKER biedt mogelijkheden om een publicatie elders te vinden (inclusief een directe link naar de publicatie online als deze beschikbaar is in een database op het internet). Zoekresultaten. Record: oai:ARNO:96842. terug naar... more
De UvA-LINKER biedt mogelijkheden om een publicatie elders te vinden (inclusief een directe link naar de publicatie online als deze beschikbaar is in een database op het internet). Zoekresultaten. Record: oai:ARNO:96842. terug naar titellijst. 1, ...
Research Interests:
The global climate is predicted to become significantly warmer over the next century. This will affect ecosystem processes and the functioning of semi natural and natural ecosystems in many parts of the world. However, as various... more
The global climate is predicted to become significantly warmer over the next century. This will affect ecosystem processes and the functioning of semi natural and natural ecosystems in many parts of the world. However, as various ecosystem processes may be affected to a different extent, balances between different ecosystem processes as well as between different ecosystems may shift and lead to major unpredicted changes. In this study four European shrubland ecosystems along a north-south temperature gradient were experimentally warmed by a novel nighttime warming technique. Biogeochemical cycling of both carbon and nitrogen was affected at the colder sites with increased carbon uptake for plant growth as well as increased carbon loss through soil respiration. Carbon uptake by plant growth was more sensitive to warming than expected from the temperature response across the sites while carbon loss through soil respiration reacted to warming in agreement with the overall Q10 and response functions to temperature across the sites. Opposite to carbon, the nitrogen mineralization was relatively insensitive to the temperature increase and was mainly affected by changes in soil moisture. The results suggest that C and N cycles respond asymmetrically to warming, which may lead to progressive nitrogen limitation and thereby acclimation in plant production. This further suggests that in many temperate zones nitrogen deposition has to be accounted for, not only with respect to the impact on water quality through increased nitrogen leaching where N deposition is high, but also in predictions of carbon sequestration in terrestrial ecosystems under future climatic conditions. Finally the results indicate that on the short term the above-ground processes are more sensitive to temperature changes than the below ground processes.
Research Interests: Climate Change, Carbon, Interaction, Carbon Sequestration, Environmental Monitoring, and 15 moreCarbon Cycle, Nitrogen Cycle, Multidisciplinary, Global Warming, Global change, Europe, Nitrogen deposition, Nitrogen, AMP, Nitrogen Leaching, Greenhouse Effect, Ecosystem, Ecosystem processes, Climatic condition, and Biogeochemical Cycle
The variation in the leaf content of phenolic compounds has been related to the UV-B changes of the environment in which plants grow. In this context, we aimed to investigate: a) whether the seasonal and altitudinal changes in the content... more
The variation in the leaf content of phenolic compounds has been related to the UV-B changes of the environment in which plants grow. In this context, we aimed to investigate: a) whether the seasonal and altitudinal changes in the content of phenolic compounds of Buxus sempervirens L. leaves and cuticles could be related to the natural fluctuations in UV-B levels and b) the possible use of specific phenolic compounds as biomarkers of ambient UV-B levels. To achieve these goals we sampled, every three months during one year, leaves of B. sempervirens along an altitudinal gradient. At the lowest and the highest altitudes, we also conducted a UV-exclusion experiment to discern whether the observed changes could be attributed to the natural variation in UV-B. Results show that total phenolic content of leaves was lower in June than in the other sampling dates, which suggests a leaf ontogenic rather than a UV-B effect on the leaf content of these compounds. Regarding the elevational gradient, the overall amount of phenolic acids and neolignan of entire leaves increased with altitude while the total amount of flavonoids in leaf cuticles decreased. However, the lack of a significant effect of our UV-exclusion treatment on the content of these compounds suggests that the observed variations along the altitudinal gradient would respond to other factors rather than to UV-B. Concomitantly, we did not find any phenolic compound in leaves or cuticles of B. sempervirens that could be considered as a biomarker of ambient UV-B levels.
Research Interests:
Research Interests: Photosynthesis, Plant Biology, Growth, Seasonality, Stable Isotope, and 12 moreSeasonal variation, Water Use, Chlorophyll a Fluorescence, Low Temperature, Biochemistry and cell biology, Stomatal Conductance, Growing Season, Infra red, Leaf Gas Exchange, Horticultural production, transpiration rate, and Water Potential
Research Interests: Evolutionary Biology, Climate Change, Plant Biology, Ecology, Mediterranean, and 12 moreLinear Model, Statistical Significance, Species Composition, Seedling Establishment, General Linear Model, Vegetation dynamics, Plant Community, Relative Abundance, Water Deficit, Community Composition, Seedling recruitment, and Redundancy Analysis
... Beaubien EG, Freeland HJ. 2000. Spring phenology trends in Alberta, Canada: links to ocean temperature. International Journal of Biometeorology 44: 5359. ...
Research Interests:
Polar forests populated high-latitude landmasses during the Cretaceous and early Paleogene when the climate was warm and the atmospheric CO2 concentration ([CO2]) was at least double that of the present-day. We investigated emission rates... more
Polar forests populated high-latitude landmasses during the Cretaceous and early Paleogene when the climate was warm and the atmospheric CO2 concentration ([CO2]) was at least double that of the present-day. We investigated emission rates and composition of monoterpenes in relation to photoinhibition and photoprotection of two evergreen and three deciduous “living fossil” tree species representative of these ancient forests, after
Research Interests:
Research Interests:
We examined chloroplast pigment variation in holm oak (Quercus ilex L.) leaves for two periods under two climatic conditions, at midday during summer. We compared variation between control (unburned) plants and plants burned the preceding... more
We examined chloroplast pigment variation in holm oak (Quercus ilex L.) leaves for two periods under two climatic conditions, at midday during summer. We compared variation between control (unburned) plants and plants burned the preceding summer, since post-fire resprouts show higher photosynthetic rates and lower thermal energy dissipation. Principal component (PC) analysis was performed on nine pigment-content variables for the two periods separately. Two PC factors (PC1 and PC2) explained 83 and 84% of the variance of the data for each period. In both periods, PC1 was marked by positive loading of pigments associated with light absorption or structural function namely neoxanthin, lutein, β-carotene, chlorophyll a, and chlorophyll b. These pigments were only affected by leaf age. In contrast, PC2 was marked by high loadings of xanthophyll-cycle pigments (associated with photoprotection), and lutein-5,6-epoxide. Leaf content of these pigments was affected by climatic conditions. In...
Research Interests:
Research Interests:
... Laura Llorens,1*Josep Pen˜uelas,1 Claus Beier,2 Bridget Emmett,3 Marc Estiarte,1 and Albert Tietema4 ... Exposure of leaves to light levels in excess of what can be utilized in photosynthesis results in photo-inhibition (Krause 1988),... more
... Laura Llorens,1*Josep Pen˜uelas,1 Claus Beier,2 Bridget Emmett,3 Marc Estiarte,1 and Albert Tietema4 ... Exposure of leaves to light levels in excess of what can be utilized in photosynthesis results in photo-inhibition (Krause 1988), which is reflected by a reduction in the ...
Research Interests: Climate Change, Photosynthesis, Water Availability, Performance, Biological Sciences, and 12 moreEnvironmental Sciences, Chlorophyll Fluorescence, Stable Isotope, Ecosystems, Temperature, Ecosystem, Chlorophyll a Fluorescence, Carbon Isotope Ratio, Photosynthetic Rate, Growing Season, Abiotic factors, and Leaf Gas Exchange
... Key words: Calluna vulgaris; climate change; drought; Erica multiflora; European gradient; flow-ering; heathland; herbivory; plant biomass; plant chemistry; shrubland; warming. ... In Wales, Denmark, and The Netherlands this was... more
... Key words: Calluna vulgaris; climate change; drought; Erica multiflora; European gradient; flow-ering; heathland; herbivory; plant biomass; plant chemistry; shrubland; warming. ... In Wales, Denmark, and The Netherlands this was Calluna vulgaris and in Spain Erica multiflora. ...
Research Interests:
Experimental studies indicate the stomatal characteristics of conifer shoots, like angiosperm leaves, are sensitive to changes in the global atmospheric CO2 concentration. Consequently, fossil conifers may serve as valuable archives of... more
Experimental studies indicate the stomatal characteristics of conifer shoots, like angiosperm leaves, are sensitive to changes in the global atmospheric CO2 concentration. Consequently, fossil conifers may serve as valuable archives of pre-Quaternary paleo-CO2 information, complementing that of other proxies and geochemical models of the long-term carbon cycle. Our study investigated this possibility by focussing on the fossil genus Frenelopsis, which
Research Interests:
... Jacob González-Solís, Juan Carlos Guix, Eduardo Mateos & Laura Llorens 122 ... González-Solís, J.; Guix, JC; Mateos, E. & Llorens, L. 2001. ... Censo de Alouatta fusca, 1812 (Platyrrhini, Atelidade) e qualidade... more
... Jacob González-Solís, Juan Carlos Guix, Eduardo Mateos & Laura Llorens 122 ... González-Solís, J.; Guix, JC; Mateos, E. & Llorens, L. 2001. ... Censo de Alouatta fusca, 1812 (Platyrrhini, Atelidade) e qualidade do habitat em dois remanescentes de Mata Atlântica em Minas Gerais. ...