References of "Aubinet, Marc"
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See detailCarbon balance of a grazed grassland in Belgium
Jerome, Elisabeth ULg; Beckers, Yves ULg; Bodson, Bernard ULg et al

in Communications in Agricultural and Applied Biological Sciences (2012, February 10)

This work seeks to analyze the carbon balance of a managed permanent grassland grazed by the “Blanc Bleu Belge” breed of cattle. The study site is located at Dorinne. The experimental field was equipped ... [more ▼]

This work seeks to analyze the carbon balance of a managed permanent grassland grazed by the “Blanc Bleu Belge” breed of cattle. The study site is located at Dorinne. The experimental field was equipped with an eddy covariance system that measured CO2 fluxes and with a micrometeorological station. Carbon exported through mowing, imported through compost application or through complementary feeds for cattle was also measured. Carbon lost through CH4 emissions was finally estimated, allowing the establishment of a full C budget. In addition, the vegetation development was followed in order to estimate herbage production and dry matter intake by grazing animals. First year full carbon budget is presented and discussed, in relation with climate conditions and management practices. [less ▲]

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See detailImpact of cultivation practices on soil respiration
Dufranne, Delphine ULg; Vancutsem, Françoise ULg; Bodson, Bernard ULg et al

Poster (2012, February 08)

In addition to its, evident, food supply function, agriculture is subjected to various pressures and has to respond to many challenges like reducing its CO2 emissions, maintaining or improving the soil ... [more ▼]

In addition to its, evident, food supply function, agriculture is subjected to various pressures and has to respond to many challenges like reducing its CO2 emissions, maintaining or improving the soil quality, maintaining productivity, sequestrating of the carbon stock in soil... Cultivation practices are known to induce a modification of soil organic matter quantity, quality and spatial distribution, which may impact dry matter decomposition kinetics. In order to bring answers to these questions, a multidisciplinary project (SOLRESIDUS) was set up by the University of Liege, Gembloux Agro-Bio Tech in collaboration with Walloon Agricultural Research Centre (CRA-W). The aim was to investigate the impact of cultivation practices (tillage and residue restitution) on crop growth, yield and environment, as well as on soil properties and on activities. In the present study, we focused on the impacts on soil CO2 fluxes. The experimental site is situated in Gembloux, in the Belgian loamy region. The plot is divided into 4 latin squares where two tillage modalities (plough after 2 stubble breaking vs only 2 stubble breaking) and two straw management practices (restitution vs. exportation) were compared. For 3 years, soil respiration was measured with automatic and manual dynamic soil chambers. Moreover, soil respiration was measured as well in cropping zone (total respiration) as in root exclusion zones created with root exclusion cylinders (heterotrophic respiration). As first results, we observed: -a significantly higher flux in plots with residue restitution, which is clearly explained by the larger amount of organic carbon prone to decomposition; -a decrease of standardized heterotrophic respiration (linked with residue decomposition) during growing seasons; -no significant differences in soil respiration between tillage modalities after 3 growing seasons. The experiment is still in progress, more years being necessary in order to evaluate the long-term impacts of cultivation practices on soil respiration. [less ▲]

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See detailDiurnal CO2 flux responses in cultivated savanna in Benin (West Africa)
Ago, Expédit Evariste ULg; Agbossou, Euloge Kossi; Galle, Sylvie et al

Scientific conference (2012, February 08)

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See detail50 Years of contrasted residue management in an agricultural crop: Impacts on the soil carbon budget and on soil heterotrophic respiration.
Buysse, Pauline ULg; Roisin, Christian; Aubinet, Marc ULg

Conference (2012, February 08)

Within the context of Climate Change, crop management exerts a strong influence on the soil carbon (C) balance. This study aims (1) to estimate the C loss by soil heterotrophic respiration (SHR) in ... [more ▼]

Within the context of Climate Change, crop management exerts a strong influence on the soil carbon (C) balance. This study aims (1) to estimate the C loss by soil heterotrophic respiration (SHR) in different residue management treatments through the establishment of their soil C budgets and (2) to compare these estimations with field SHR measurements. Three contrasted treatments were considered: Residue Export (RE), Farm Yard Manure addition (FYM) and Residue Restitution after harvest (RR). They were established in 1959 and continuously applied since then at an experimental field located in the Hesbaye region in Belgium. The soil C budget was calculated for each treatment on the basis of total soil organic C content measurements and C input data compiled since the beginning of the experiment. This allowed estimating the C loss by SHR in the different treatments. SHR measurements were performed in 2010 and 2011 to compare them with the budget-based estimations and to assess SHR sensitivity to temperature in the different treatments. The soil C budgets showed that the soil under the RR treatment was likely to undergo the largest C loss by SHR since the beginning of the experiment. The comparison between the results from the C budget and the SHR field measurements, performed 50 years after the experiment had begun, did however show that the treatment that received the largest amount of crop residues (RR) did not necessarily sequestrate the most C or produce the largest CO2 fluxes (FYM). Besides, no significant difference between treatments was observed in the field measurements in terms of SHR sensitivity to temperature. Laboratory investigations (microbial biomass, basal respiration, metabolic diversity and soil fractionation) will later be performed to better understand the effects of long-term residue management on soil C dynamics. [less ▲]

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See detailAbiotic and biotic control of methanol exchanges in a temperate mixed forest
Laffineur, Quentin ULg; Aubinet, Marc ULg; Schoon, N. et al

in Atmospheric Chemistry and Physics (2012), 12

Methanol exchanges over a mixed temperate forest in the Belgian Ardennes were measured for more than one vegetation season using disjunct eddy-covariance by a mass scanning technique and Proton Transfer ... [more ▼]

Methanol exchanges over a mixed temperate forest in the Belgian Ardennes were measured for more than one vegetation season using disjunct eddy-covariance by a mass scanning technique and Proton Transfer Reaction Mass Spectrometry (PTR-MS). Half-hourly methanol fluxes were measured in the range of −0.6 μgm−2 s−1 to 0.6 μgm−2 s−1, and net daily methanol fluxes were generally negative in summer and autumn and positive in spring. On average, the negative fluxes dominated (i.e. the site behaved as a net sink), in contrast to what had been found in previous studies. An original model describing the adsorption/desorption of methanol in water films present in the forest ecosystem and the methanol degradation process was developed. Its calibration, based on field measurements, predicted a mean methanol degradation rate of −0.0074 μgm−2 s−1 and a half lifetime for methanol in water films of 57.4 h. Biogenic emissions dominated the exchange only in spring, with a standard emission factor of 0.76 μgm−2 s−1. The great ability of the model to reproduce the long-term evolution, as well as the diurnal variation of the fluxes, suggests that the adsorption/desorption and degradation processes play an important role in the global methanol budget. This result underlines the need to conduct long-term measurements in order to accurately capture these processes and to better estimate methanol fluxes at the ecosystem scale. [less ▲]

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See detailThermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms
Niu, Shuli; Fei, Shenfeng; Yuan, Wenping et al

in New Phytologist (2012), 194

• It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not ... [more ▼]

• It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. • Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem- level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms. • We found that the temperature response of NEE followed a peak curve, with the optimum temperature (corresponding to the maximum magnitude of NEE) being positively correlated with annual mean temperature over years and across sites. Shifts of the optimum temperature of NEE were mostly a result of temperature acclimation of gross primary productivity (upward shift of optimum temperature) rather than changes in the temperature sensitivity of ecosystem respiration. • Ecosystem-level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate ecosystem–climate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models. [less ▲]

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See detailGround-based Network of NDVI measurements for tracking temporal dynamics of canopy structure and vegetation phenology in different biomes
Soudani, K.; Hmimina, K.; Delpierre, N. et al

in Remote Sensing of Environment (2012), 123

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See detailChapter 1: The eddy covariance method
Foken, Thomas; Aubinet, Marc ULg; Leuning, Ray

in Aubinet, Marc; Vesala, Timo; Papale, Dario (Eds.) Eddy covariance: A Practical Guide to Measurement and Data Analysis (2012)

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See detailChapter 3: Data Acquisition and Flux Calculations
Rebmann, Corinna; Kolle, Olaf; Heinesch, Bernard ULg et al

in Aubinet, Marc; Vesala, Timo; Papale, Dario (Eds.) Eddy Covariance: A Practical Guide to Measurement and Data Analysis (2012)

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See detailChapter 4: Corrections and data quality control
Foken, Thomas; Leuning, Ray; Oncley, Steven R. et al

in Aubinet, Marc; Vesala, Timo; Papale, Dario (Eds.) Eddy Covariance: A Practical Guide to Measurement and Data Analysis (2012)

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See detailChapter 5: Night time Flux correction
Aubinet, Marc ULg; Feigenwinter, Christian; Heinesch, Bernard ULg et al

in Aubinet, Marc; Vesala, Timo; Papale, Dario (Eds.) Eddy Covariance: A Practical Guide to Measurement and Data Analysis (2012)

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See detailChapter 7: Uncertainty quantification
Richardson, Andrew D.; Aubinet, Marc ULg; Barr, Alan G. et al

in Aubinet, Marc; Vesala, Timo; Papale, Dario (Eds.) Eddy Covariance: A Practical Guide to Measurement and Data Analysis (2012)

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See detailEddy Covariance: A Practical Guide to Measurement and Data Analysis
Aubinet, Marc ULg; Vesala, Timo; Papale, Dario

Book published by Springer (2012)

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See detailApport de l'approche multicouche et du signal isotopique pour la compréhension de la respiration du sol en écosystème forestier
Goffin, Stéphanie ULg; Longdoz, Bernard; Aubinet, Marc ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(4), 575-584

Le flux de dioxyde de carbone émanant du sol participe de manière prépondérante au cycle du carbone. On estime son amplitude à 68 ± 4 Pg C/an. En forêt tempérée, il représente approximativement 60-80% des ... [more ▼]

Le flux de dioxyde de carbone émanant du sol participe de manière prépondérante au cycle du carbone. On estime son amplitude à 68 ± 4 Pg C/an. En forêt tempérée, il représente approximativement 60-80% des émissions totales de CO2 de l’écosystème (respiration de l’écosystème). Compte tenu de l’ampleur de ce flux et des conséquences qu’aurait une quelconque modification de son amplitude sur le chargement en dioxyde de carbone de l’atmosphère, il est primordial d’améliorer la connaissance des mécanismes qui le régissent et de connaître précisément l’influence des variables du milieu (édaphiques et climatiques). Cet article vise à montrer l’intérêt d’effectuer des analyses multicouches des mécanismes à l’origine de ce flux (transport et production) plutôt que de restreindre les études à la surface du sol. De plus, cet article souligne le bénéfice apporté par l’outil isotopique pour améliorer la compréhension mécaniste de ce flux. [less ▲]

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See detailCO2 exchange above a cultivated savanna in sudanian region in northern part of Benin (West Africa)
Ago, Expédit Evariste ULg; Agbossou, Euloge; Galle, Sylvie et al

Poster (2011, October)

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See detailClear link between drought stress, photosynthesis and biogenic volatile organic compounds in Fagus sylvatica L.
Šimpraga, M.; Verbeeck, H.; Demarcke, M. et al

in Atmospheric Environment (2011), 45(30), 5254-5259

Direct plant stress sensing is the key for a quantitative understanding of drought stress effects on biogenic volatile organic compound (BVOC) emissions. A given level of drought stress might have a ... [more ▼]

Direct plant stress sensing is the key for a quantitative understanding of drought stress effects on biogenic volatile organic compound (BVOC) emissions. A given level of drought stress might have a fundamentally different effect on the BVOC emissions of different plants. For the first time, we continuously quantified the level of drought stress in a young potted beech (Fagus sylvatica L.) with a linear variable displacement transducer (LVDT) installed at stem level in combination with simultaneous measurements of BVOC emissions and photosynthesis rates at leaf level. This continuous set of measurements allowed us to examine how beech alters its pattern of photosynthesis and carbon allocation to BVOC emissions (mainly monoterpenes, MTs) and radial stem growth during the development of drought stress. We observed an increasing-decreasing trend in the MT emissions as well as in the fraction of assimilated carbon re-emitted back into the atmosphere (ranging between 0.14 and 0.01%). We were able to link these dynamics to pronounced changes in radial stem growth, which served as a direct plant stress indicator. Interestingly, we detected a sudden burst in emission of a non-identified, non-MT BVOC species when drought stress was acute (i.e. pronounced negative stem growth). This burst might have been caused by a certain stress-related green leaf volatile, which disappeared immediately upon re-watering and thus the alleviation of drought stress. These results highlight that direct plant stress sensing creates opportunities to understand the overall complexity of stress-related BVOC emissions. [less ▲]

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See detailConstitutive versus heat and biotic stress induced BVOC emissions in Pseudotsuga menziesii
Joó, É.; Dewulf, J.; Amelynck, C. et al

in Atmospheric Environment (2011), 45(22), 3655-3662

Induced volatiles have been a focus of recent research, as not much is known of their emission behavior or atmospheric contribution. BVOC emissions were measured from Pseudotsuga menziesii saplings under ... [more ▼]

Induced volatiles have been a focus of recent research, as not much is known of their emission behavior or atmospheric contribution. BVOC emissions were measured from Pseudotsuga menziesii saplings under natural environmental conditions, using a dynamic branch enclosure system and GC-MS for their analysis. We determined temperature and light dependency of the individual compounds, studied seasonality of the emissions and discuss the effect of heat stress in comparison with two specific biotic stresses that occurred naturally on the trees. A standardized emission rate of 6.8 μg g (dw) -1 h -1 for monoterpenes under stressed conditions was almost a magnitude higher than that obtained for healthy trees (0.8 ± 0.2 μg g (dw) -1 h -1), with higher beta factors characterizing the stressed trees. The response of the emissions to light intensity was different for the individual compounds, suggesting a distinct minimum light intensity to reach saturation. Heat stress changed the relative contribution of specific volatiles, with larger extent of increase of sesquiterpenes, methyl salicylate and linalool emissions compared to monoterpenes. Biotic stress kept low the emissions of sesquiterpenes, (E)-4,8-dimethyl-1,3,7-nonatriene and methylbutenol isomers, and increased the level of methyl salicylate and monoterpenes. The ratio of β-pinene/α-pinene was also found to be significantly enhanced from 1.3 to 2.4 and 3.2 for non-stressed, heat stressed and combined biotic and heat stressed, respectively. [less ▲]

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See detailEffects of long term soil organic matter restitution mode on soil heterotrophic respiration and soil biological properties.
Buysse, Pauline ULg; Carnol, Monique ULg; Malchair, Sandrine ULg et al

Poster (2011, July)

Soil heterotrophic respiration (SHR) is the process by which CO2 is released during organic matter decomposition. It is generally expected that SHR can act as a positive feedback to global warming ... [more ▼]

Soil heterotrophic respiration (SHR) is the process by which CO2 is released during organic matter decomposition. It is generally expected that SHR can act as a positive feedback to global warming, therefore leading to more CO2 release into the atmosphere. It is thus important to better understand this process. Particularly, agricultural soils may behave as important CO2 sources that are strongly influenced by soil and crop management (e.g. organic matter restitution modes, hereafter “OM-RM”). The present study aimed at determining if, after more than 50 years of application of different OM-RM, (1) significant differences of SHR fluxes can be observed between treatments, (2) SHR responses to temperature and soil moisture content can be affected by the OM-RM and (3) the experimental design is suitable to assess potential differences between treatments. The experimental field is situated in Liroux, near Gembloux in Belgium. At that site, a long term experiment with different OM-RM runs from 1959 onwards. For the present study, three contrasted treatments were considered: (1) exportation of all residues after harvest, (2) addition of manure once every three to four years and (3) restitution of residues after harvest. SHR flux measurements were carried out manually on fourteen occasions from 2 April to 30 July 2010, using a dynamic closed chamber system. Temperature and soil moisture content at 5 cm depth were also measured manually. Results showed that after more than 50 years of OM-RM application, no significant differences could be observed between the three treatments in terms of SHR fluxes and SHR responses to temperature or soil moisture, while the soil organic carbon content did vary significantly between them. The sensitivity to temperature was quite low in all treatments, with a mean Q10 value of 1,36. Besides, SHR fluxes were seen to be more responsive to increases in soil water content than to absolute soil moisture content values. Indeed, when soil moisture content increased between two consecutive measurement dates, the ratio of the corresponding SHR fluxes was larger than 1. Particularly dry conditions in 2010 may actually have caused the fluxes to be very low, making the assessment of differences between treatments more difficult. Moreover, soil dryness is likely to be responsible for the SHR flux increases after rain events, as caused by re-solubilization of organic compounds. Also, an important spatial variability was observed, which may have obscured the assessment of potential differences between treatments. Further investigations will consist in performing a new flux measurement campaign in 2011 that will take the spatial variability issue into account, and in monitoring microbial and soil properties in the different treatments, such as microbial biomass, metabolic activity and labile carbon. [less ▲]

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