The Experts below are selected from a list of 8523 Experts worldwide ranked by ideXlab platform
Serge Rambal - One of the best experts on this subject based on the ideXlab platform.
-
stem co2 efflux and its contribution to ecosystem co2 efflux decrease with drought in a Mediterranean Forest stand
Agricultural and Forest Meteorology, 2014Co-Authors: Jesus Rodriguezcalcerrada, Morine Lempereur, Jean-marc Ourcival, Maria Del Carmen Del Rey, Richard Joffre, Nicolas K Martinstpaul, Serge RambalAbstract:Abstract The rate of metabolic processes demanding energy in tree stems changes in relation with prevailing climatic conditions. Tree water availability can affect stem respiration through impacts on growth, phloem transport or maintenance of diverse cellular processes, but little is known on this topic. Here we monitored seasonal changes in stem CO 2 efflux ( F s ), radial growth, sap flow and non-structural carbohydrates in trees of Quercus ilex in a Mediterranean Forest stand subjected since 2003 to either partial (33%) throughfall exclusion ( E ) or unchanged throughfall ( C ). F s increased exponentially during the day by an effect of temperature, although sap flow attenuated the increase in F s during the day time. Over the year, F s also increased exponentially with increasing temperatures, but F s computed at a standard temperature of 15 °C ( F s 15 ) varied by almost 4-fold among dates. F s 15 was the highest after periods of stem growth and decreased as tree water availability decreased, similarly in C and E treatments. The decline in F s 15 was not linked to a depletion of soluble sugars, which increased when water stress was higher. The proportion of ecosystem respiration attributed to the stems was highest following stem growth (23.3%) and lowest during the peak of drought (6.5%). High within-year variability in F s 15 makes unadvisable to pool annual data of F s vs. temperature to model F s at short time scales (hours to months) in Mediterranean-type Forest ecosystems. We demonstrate that water availability is an important factor governing stem CO 2 efflux and suggest that trees in Mediterranean environments acclimate to seasonal drought by reducing stem respiration. Stem respiratory rates do not seem to change after a long-term increase in drought intensity, however.
-
Stem CO2 efflux and its contribution to ecosystem CO2 efflux decrease with drought in a Mediterranean Forest stand
Agricultural and Forest Meteorology, 2014Co-Authors: Jesús Rodríguez-calcerrada, Nicolas Martin-stpaul, Morine Lempereur, Jean-marc Ourcival, Maria Del Carmen Del Rey, Richard Joffre, Serge RambalAbstract:The rate of metabolic processes demanding energy in tree stems changes in relation with prevailing climatic conditions. Tree water availability can affect stem respiration through impacts on growth, phloem transport or maintenance of diverse cellular processes, but little is known on this topic. Here we monitored seasonal changes in stem CO2 efflux (F-s), radial growth, sap flow and non-structural carbohydrates in trees of Quercus ilex in a Mediterranean Forest stand subjected since 2003 to either partial (33%) throughfall exclusion (E) or unchanged throughfall (C). F-s increased exponentially during the day by an effect of temperature, although sap flow attenuated the increase in F-s during the day time. Over the year, F-s also increased exponentially with increasing temperatures, but F-s computed at a standard temperature of 15 degrees C (F-s(15)) varied by almost 4-fold among dates. F-s(15) was the highest after periods of stem growth and decreased as tree water availability decreased, similarly in C and E treatments. The decline in F-s(15) was not linked to a depletion of soluble sugars, which increased when water stress was higher. The proportion of ecosystem respiration attributed to the stems was highest following stem growth (23.3%) and lowest during the peak of drought (6.5%). High within-year variability in F-s(15) makes unadvisable to pool annual data of F-s vs. temperature to model F-s at short time scales (hours to months) in Mediterranean-type Forest ecosystems. We demonstrate that water availability is an important factor governing stem CO2 efflux and suggest that trees in Mediterranean environments acclimate to seasonal drought by reducing stem respiration. Stem respiratory rates do not seem to change after a long-term increase in drought intensity, however.
-
phenological responses to extreme droughts in a Mediterranean Forest
Global Change Biology, 2011Co-Authors: Laurent Misson, Jean-marc Ourcival, David Degueldre, Christian Collin, Raquel Rodriguez, Alain Rocheteau, Serge RambalAbstract:Mediterranean regions are projected to experience more frequent, prolonged and severe drought as a consequence of climate change. We used a retractable rainfall shelter, to investigate the impact of extreme droughts on the development of Quercus ilex leaves, flowers and fruit. In 2008, 97% of rainfall was excluded from a Forest plot during the autumn, representing 50% of the 1127mm of rain that fell during the year. In 2009, 87% of rainfall was excluded during the spring, representing 58% of the 749mm that fell during the year. The rainfall shelter did not impact neither incident radiation nor air temperature. Autumn rainfall exclusion did not significantly affect leaf, flowers or fruit development. Spring rainfall exclusion resulted in larger and more sustained depression of leaf water potential during the key phases of foliar and floral development. Consequently, only half of the sampled trees (6) reached the shoot lengthening stage which leads to functionally mature leaves (phenophase 4), with one abandoning leaf development at budburst (phenophase 3) and the other two at the bud swelling stage (phenophase 2). All trees of the control plot passed phenophase 4, with most reaching complete leaf development. The impact of extreme droughts on flower development differed between the sexes. The spring exclusion had no effect on male flower, but only one of six trees completed female fruit maturation, compared with four in the control plot. The difference between the male and female drought impacts is likely attributable to the occurrence of male floral development before the period of lowest leaf water potential, and to the lower resource allocation requirements of male flowers. The information provided by our experimental approach may constitute a crucial step to evaluate the impact of increasing drought due to climate change on the most dominant Mediterranean tree species and to help drawing a full picture of the ecological consequences of the decline in water resource on Forest dynamics under changing conditions.
Stefano Carnicelli - One of the best experts on this subject based on the ideXlab platform.
-
Biological and physico-chemical processes influence cutin and suberin biomarker distribution in two Mediterranean Forest soil profiles
Biogeochemistry, 2013Co-Authors: Anna Andreetta, Marie-france Dignac, Stefano CarnicelliAbstract:Recent investigations have shown macromolecules, such as cutins, and suberins as effective markers for above and belowground plant tissues. These biopolyesters contain structural units specific for different litter components and for root biomass. The aim of this work was to understand the fate of plant organic matter (OM) in Mediterranean Forest soils by evaluating the incorporation of cutin and suberin by measuring specific biomarkers. Soil and plant tissue (leaves, woods and roots) samples were collected in two mixed Mediterranean Forests of Quercus ilex (holm oak) in costal stands in Tuscany (central Italy), which have different ecological and edaphic features. Ester-bound lipids of mineral and organic horizons and the overlying vegetation were analysed using the saponification method in order to depolymerise cutins and suberins and release their specific structural units. Cutin and suberin specific aliphatic monomers were identified and quantified by gas chromatographic techniques. The distribution of cutin and suberin specific monomers in plant tissue suggested that mid-chain hydroxy acids can be used as leaf-specific markers and α,ω-alkanedioic acids and ωC_18:1 as root-specific markers. Differences in the distributions of biomarkers specific for above and belowground plant-derived OM was observed in the two types of soils, suggesting contrasted degradation, stabilisation and transport mechanisms that may be related to soil physico-chemical properties. The acidic and dry soil appeared to inhibit microbial activity, favouring stabilization of leaf-derived compounds, while, in the more fertile soil, protection within aggregates appeared to better preserve root-derived compounds.
-
Biological and physico-chemical processes influence cutin and suberin biomarker distribution in two Mediterranean Forest soil profiles
Biogeochemistry, 2013Co-Authors: Anna Andreetta, Marie-france Dignac, Stefano CarnicelliAbstract:Recent investigations have shown macromolecules, such as cutins, and suberins as effective markers for above and belowground plant tissues. These biopolyesters contain structural units specific for different litter components and for root biomass. The aim of this work was to understand the fate of plant organic matter (OM) in Mediterranean Forest soils by evaluating the incorporation of cutin and suberin by measuring specific biomarkers. Soil and plant tissue (leaves, woods and roots) samples were collected in two mixed Mediterranean Forests of Quercus ilex (holm oak) in costal stands in Tuscany (central Italy), which have different ecological and edaphic features. Ester-bound lipids of mineral and organic horizons and the overlying vegetation were analysed using the saponification method in order to depolymerise cutins and suberins and release their specific structural units. Cutin and suberin specific aliphatic monomers were identified and quantified by gas chromatographic techniques. The distribution of cutin and suberin specific monomers in plant tissue suggested that mid-chain hydroxy acids can be used as leaf-specific markers and alpha,omega-alkanedioic acids and omega C-18:1 as root-specific markers. Differences in the distributions of biomarkers specific for above and belowground plant-derived OM was observed in the two types of soils, suggesting contrasted degradation, stabilisation and transport mechanisms that may be related to soil physico-chemical properties. The acidic and dry soil appeared to inhibit microbial activity, favouring stabilization of leaf-derived compounds, while, in the more fertile soil, protection within aggregates appeared to better preserve root-derived compounds.
-
Forest humus forms as potential indicators of soil carbon storage in Mediterranean environments
Biology and Fertility of Soils, 2011Co-Authors: Anna Andreetta, Rossano Ciampalini, Pierpaolo Moretti, Simona Vingiani, Giorgio Poggio, Giorgio Matteucci, Francesca Tescari, Stefano CarnicelliAbstract:The aim of this work was to investigate the potential of Forest humus forms as indicators of soil C storage. To this purpose, Mediterranean Forest soils in Southern and Central Italy were examined. Sites differed for elevation, climate, parent material and vegetation conditions, while summer drought was the common ecological factor. A morpho-functional criterion, based on holorganic layers thickness and A horizon properties, was used to classify humus forms, which ranged from Dysmoder to Eumull. Such variability allowed understanding of factors influencing organic matter storage. The relations between carbon stock and humus form were investigated for the topsoil layer (0–20 cm), which was supposed to contain the soil C pools most sensitive to climate change. We found that humus forms can be grouped in statistically different populations, with respect to topsoil C stocks. The use of A horizon structure was the main diagnostic criterion and represented the most effective approach to humus classification in Mediterranean conditions. It appears that humus forms have a clear potential as indicators of organic carbon status in Mediterranean Forest soils.
Francois Lefevre - One of the best experts on this subject based on the ideXlab platform.
-
Adaptive measures for mountain Mediterranean Forest ecosystem services under climate and land cover change in the Mont-Ventoux natural Regional Park, France
Regional Environmental Change, 2021Co-Authors: Laetitia Tufféry, Hendrik Davi, Noelia Lopez Garcia, Eric Rigolot, Florence Jean, Anne Stenger, Francois LefevreAbstract:Climate change (CC) and land use and land cover change (LULCC) threaten Mediterranean Forests and the ecosystem services (ES) they provide. In complex socio-ecological systems and under high uncertainties, the resilience of ES has become the target objective for adaptive management strategies driven by decision-makers and local stakeholders. This work develops an integrative and territorial approach to combining biophysical modeling and local managers’ assessments to elaborate scenarios of LULCC in response to climate and socioeconomic changes. It also evaluates the impacts of Forest ecosystem changes on coupled ES for different time horizons for a case study of the mountain Mediterranean Forests of Mont-Ventoux Natural Regional Park. The results demonstrate first that the future ES provisions predicted by biophysical modeling in this area are less affected by CC than expected by local managers. Furthermore, LULCC increases the changes in ES provision and accentuates the difference between climate scenarios. These results originate from a combination of two effects: (1) pessimistic predictions by local managers and, as a consequence, and (2) anticipatory actions that tend to reinforce or even accelerate the expected changes in the mountain Mediterranean Forest area.
-
Adaptive measures for mountain Mediterranean Forest ecosystem services under climate and land cover change in the Mont-Ventoux regional nature park, France
Regional Environmental Change, 2021Co-Authors: Laetitia Tufféry, Hendrik Davi, Noelia Lopez Garcia, Eric Rigolot, Florence Jean, Anne Stenger, Francois LefevreAbstract:Climate change (CC) and land use and land cover change (LULCC) threaten Mediterranean Forests and the ecosystem services (ES) they provide. In complex socio-ecological systems and under high uncertainties, the resilience of ES has become the target objective for adaptive management strategies driven by decision-makers and local stakeholders. This work develops an integrative and territorial approach to combining biophysical modeling and local managers’ assessments to elaborate scenarios of LULCC in response to climate and socioeconomic changes. It also evaluates the impacts of Forest ecosystem changes on coupled ES for different time horizons for a case study of the mountain Mediterranean Forests of Mont-Ventoux regional nature park. The results demonstrate first that the future ES provisions predicted by biophysical modeling in this area are less affected by CC than expected by local managers. Furthermore, LULCC increases the changes in ES provision and accentuates the difference between climate scenarios. These results originate from a combination of two effects: (1) pessimistic predictions by local managers and, as a consequence, and (2) anticipatory actions that tend to reinforce or even accelerate the expected changes in the mountain Mediterranean Forest area.
-
Introduction to Mediterranean Forest Systems: Mediterranean Basin
Insects and Diseases of Mediterranean Forest Systems, 2016Co-Authors: Francois Lefevre, Bruno FadyAbstract:All around the Mediterranean, Forest systems have been shaped by long-term anthropogenic impacts. Today, they provide multiple goods and services. We show how the social-ecological system approach offers a good framework to understand their biodiversity, functioning and dynamics. Mediterranean Forests have a huge biodiversity, not only in terms of the number of species but also in terms of within-species genetic diversity (at least tree species). We present a tentative typology of Mediterranean Forests regarding this biodiversity. Then, we explain how the dynamics of Mediterranean Forests is driven in particular by a combination of three characteristics: specific environmental constraints (mainly summer water deficit), a marked spatial heterogeneity of the environment at all scales, disturbance regime (e.g. fire, droughts, pest attacks, human pressure) of variable intensity and frequency. The future challenges for the Mediterranean Forests will be to respond simultaneously to: (i) increased threats related to climate change and human pressure, (ii) new demand for multiple ecosystem services locally, (iii) emerging interest for Mediterranean resources to support adaptive strategies in other regions.
-
Introduction to Mediterranean Forest systems: Mediterranean basin
2016Co-Authors: Bruno Fady, Francois LefevreAbstract:Introduction to Mediterranean Forest systems: Mediterranean basin
-
Towards the integration of biodiversity dynamics in SES: the example of Mediterranean Forest systems
2015Co-Authors: Francois LefevreAbstract:Towards the integration of biodiversity dynamics in SES: the example of Mediterranean Forest systems. Atelier Prospective BiodivMex
Anna Andreetta - One of the best experts on this subject based on the ideXlab platform.
-
Biological and physico-chemical processes influence cutin and suberin biomarker distribution in two Mediterranean Forest soil profiles
Biogeochemistry, 2013Co-Authors: Anna Andreetta, Marie-france Dignac, Stefano CarnicelliAbstract:Recent investigations have shown macromolecules, such as cutins, and suberins as effective markers for above and belowground plant tissues. These biopolyesters contain structural units specific for different litter components and for root biomass. The aim of this work was to understand the fate of plant organic matter (OM) in Mediterranean Forest soils by evaluating the incorporation of cutin and suberin by measuring specific biomarkers. Soil and plant tissue (leaves, woods and roots) samples were collected in two mixed Mediterranean Forests of Quercus ilex (holm oak) in costal stands in Tuscany (central Italy), which have different ecological and edaphic features. Ester-bound lipids of mineral and organic horizons and the overlying vegetation were analysed using the saponification method in order to depolymerise cutins and suberins and release their specific structural units. Cutin and suberin specific aliphatic monomers were identified and quantified by gas chromatographic techniques. The distribution of cutin and suberin specific monomers in plant tissue suggested that mid-chain hydroxy acids can be used as leaf-specific markers and α,ω-alkanedioic acids and ωC_18:1 as root-specific markers. Differences in the distributions of biomarkers specific for above and belowground plant-derived OM was observed in the two types of soils, suggesting contrasted degradation, stabilisation and transport mechanisms that may be related to soil physico-chemical properties. The acidic and dry soil appeared to inhibit microbial activity, favouring stabilization of leaf-derived compounds, while, in the more fertile soil, protection within aggregates appeared to better preserve root-derived compounds.
-
Biological and physico-chemical processes influence cutin and suberin biomarker distribution in two Mediterranean Forest soil profiles
Biogeochemistry, 2013Co-Authors: Anna Andreetta, Marie-france Dignac, Stefano CarnicelliAbstract:Recent investigations have shown macromolecules, such as cutins, and suberins as effective markers for above and belowground plant tissues. These biopolyesters contain structural units specific for different litter components and for root biomass. The aim of this work was to understand the fate of plant organic matter (OM) in Mediterranean Forest soils by evaluating the incorporation of cutin and suberin by measuring specific biomarkers. Soil and plant tissue (leaves, woods and roots) samples were collected in two mixed Mediterranean Forests of Quercus ilex (holm oak) in costal stands in Tuscany (central Italy), which have different ecological and edaphic features. Ester-bound lipids of mineral and organic horizons and the overlying vegetation were analysed using the saponification method in order to depolymerise cutins and suberins and release their specific structural units. Cutin and suberin specific aliphatic monomers were identified and quantified by gas chromatographic techniques. The distribution of cutin and suberin specific monomers in plant tissue suggested that mid-chain hydroxy acids can be used as leaf-specific markers and alpha,omega-alkanedioic acids and omega C-18:1 as root-specific markers. Differences in the distributions of biomarkers specific for above and belowground plant-derived OM was observed in the two types of soils, suggesting contrasted degradation, stabilisation and transport mechanisms that may be related to soil physico-chemical properties. The acidic and dry soil appeared to inhibit microbial activity, favouring stabilization of leaf-derived compounds, while, in the more fertile soil, protection within aggregates appeared to better preserve root-derived compounds.
-
Forest humus forms as potential indicators of soil carbon storage in Mediterranean environments
Biology and Fertility of Soils, 2011Co-Authors: Anna Andreetta, Rossano Ciampalini, Pierpaolo Moretti, Simona Vingiani, Giorgio Poggio, Giorgio Matteucci, Francesca Tescari, Stefano CarnicelliAbstract:The aim of this work was to investigate the potential of Forest humus forms as indicators of soil C storage. To this purpose, Mediterranean Forest soils in Southern and Central Italy were examined. Sites differed for elevation, climate, parent material and vegetation conditions, while summer drought was the common ecological factor. A morpho-functional criterion, based on holorganic layers thickness and A horizon properties, was used to classify humus forms, which ranged from Dysmoder to Eumull. Such variability allowed understanding of factors influencing organic matter storage. The relations between carbon stock and humus form were investigated for the topsoil layer (0–20 cm), which was supposed to contain the soil C pools most sensitive to climate change. We found that humus forms can be grouped in statistically different populations, with respect to topsoil C stocks. The use of A horizon structure was the main diagnostic criterion and represented the most effective approach to humus classification in Mediterranean conditions. It appears that humus forms have a clear potential as indicators of organic carbon status in Mediterranean Forest soils.
Iolanda Filella - One of the best experts on this subject based on the ideXlab platform.
-
Leaf and stand-level carbon uptake of a Mediterranean Forest estimated using the satellite-derived reflectance indices EVI and PRI
International Journal of Remote Sensing, 2012Co-Authors: Martín F. Garbulsky, Romà Ogaya, Josep Peñuelas, Iolanda FilellaAbstract:Various aspects of global environmental change affect plant photosynthesis, the primary carbon input in ecosystems. Thus, accurate methods of measuring plant photosynthesis are important. Remotely sensed spectral indices can monitor in detail the green biomass of ecosystems, which provides a measure of potential photosynthetic capacity. In evergreen vegetation types, however, such as Mediterranean Forests, the amount of green biomass changes little during the growing season and, therefore, changes in green biomass are not responsible for changes in photosynthetic rates in those Forests. This study examined the net photosynthetic rates and the diametric increment of stems in a Mediterranean Forest dominated by Quercus ilex using three spectral indices normalized difference vegetation index NDVI, enhanced vegetation index EVI, and photochemical reflectance index PRI derived from Moderate Resolution Imaging Spectroradiometer MODIS sensors. Average annual EVI accounted for 83% of the variability of the diametric increment of Q. ilex stems over a 10 year period. NDVI was marginally correlated with the diametric increment of stems. This study was the first to identify a significant correlation between net photosynthetic rates and radiation use efficiency at the leaf level using PRI derived from satellite data analysed at the ecosystem level. These results suggest that each spectral index provided different and complementary information about ecosystem carbon uptake in a Mediterranean Q. ilex Forest.
-
Remote estimation of carbon dioxide uptake by a Mediterranean Forest
Global Change Biology, 2008Co-Authors: Martín F. Garbulsky, Josep Peñuelas, Dario Papale, Iolanda FilellaAbstract:The estimation of the carbon balance in ecosystems, regions, and the biosphere is currently one of the main concerns in the study of the ecology of global change. Current remote sensing methodologies for estimating gross primary productivity are not satisfactory because they rely too heavily on (i) the availability of climatic data, (ii) the definition of land-use cover, and (iii) the assumptions of the effects of these two factors on the radiation-use efficiency of vegetation (RUE). A new methodology is urgently needed that will actually assess RUE and overcome the problems associated with the capture of fluctuations in carbon absorption in space and over time. Remote sensing techniques such as the widely used reflectance vegetation indices (e.g. NDVI, EVI) allow green plant biomass and therefore plant photosynthetic capacity to be assessed. However, there are vegetation types, such as the Mediterranean Forests, with a very low seasonality of these vegetation indices and a high seasonality of carbon uptake. In these cases it is important to detect how much of this capacity is actually realized, which is a much more challenging goal. The photochemical reflectance index (PRI) derived from freely available satellite information (MODIS sensor) presented for a 5-year analysis for a Mediterranean Forest a positive relationship with the RUE. Thus, we show that it is possible to estimate RUE and GPP in real time and therefore actual carbon uptake of Mediterranean Forests at ecosystem level using the PRI. This conceptual and technological advancement would avoid the need to rely on the sometimes unreliable maximum RUE.
-
deuterium labelling of roots provides evidence of deep water access and hydraulic lift by pinus nigra in a Mediterranean Forest of ne spain
Environmental and Experimental Botany, 2003Co-Authors: Josep Peñuelas, Iolanda FilellaAbstract:Abstract We studied the tree access to deep water sources and the possibility of hydraulic lift from the deep roots of a Pinus nigra tree to the shallow soil layers in a Mediterranean Forest of NE Spain. We also studied the use of hydraulically lifted water by neighboring trees, shrubs, and sprouts. We enriched the roots of a large P. nigra (10 m tall) with deuterium by accessing them from a below ground cave. During the next 3 days we measured stable deuterium isotopic composition of xylem sap, shoot predawn and midday water potentials, and the leaf δ 13 C and δ 15 N of the P. nigra tree, neighboring Quercus ilex ballota trees and sprouts , and Juniperus oxycedrus shrubs. The study was conducted both in dry summer and in wet spring. In summer, deuterated water absorbed by deep roots of P. nigra appeared in the stem water of neighboring plants and in surface soil. The most δD -enriched plant xylem sap was found in the enriched P. nigra tree, followed by the Q. ilex sprouts, the small Q. ilex trees and the surface soil (15 cm). All these trends disappeared in the wet spring season, when HDO only slightly appeared in the surface soil. The results show that the studied P. nigra tree accesses deep water source and conducts hydraulic lift in this Mediterranean Forest in dry summer but not necessarily in wet spring.