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See detailImpact of future Greenland deglaciation on global weathering fluxes and atmospheric CO2
Munhoven, Guy ULg; Brovkin, Victor; Ganopolski, A. et al

Conference (2007)

About 1.76×10^6 km2 of Greenland are currently covered by ice. It is expected that this large ice mass will melt away over the next 3000 years if anthropogenic CO2 emissions continue to rise (Alley et al ... [more ▼]

About 1.76×10^6 km2 of Greenland are currently covered by ice. It is expected that this large ice mass will melt away over the next 3000 years if anthropogenic CO2 emissions continue to rise (Alley et al., 2006). As a result, the bedrock currently covered by ice will lie free and become subject to chemical weathering. The resulting weathering fluxes will contribute to increase both the consumption rate of atmospheric CO2 and the production rate of riverine bicarbonate. Increasing these two fluxes will tend to decrease the atmospheric CO2 partial pressure, as a result of the modified ocean-atmosphere carbon cycle. Chemical weathering may thus possibly act as a negative feedback in the Greenhouse World. Other changes (e.g., vegetation cover and additional climate change) concomitant with the melting of the Greenland ice-sheet may either amplify or dampen, if not reverse the weathering effect. Here we use the intermediate complexity Earth System model CLIMBER-2 to quantify and analyse the weathering flux changes that result from the projected melting of the Greenland ice sheet and the implications for atmospheric CO2. The biogeochemical module of CLIMBER-2 has been extended to account for the consumption of atmospheric CO2 and the production of riverine bicarbonate by continental weathering processes, as a function of geographically distributed runoff (interactively provided by the CLIMBER-2 climate module) and lithology (derived from Amiotte Suchet et al., 2003). We find that the increased weathering processes alone would lead to a sustained 0.2 ppm/kyr decrease in atmospheric pCO2. The climate change resulting from the deglaciation of Greenland reduces the magnitude of this trend to 0.1 ppm/kyr. Only in the case where the effect of freshly comminuted bedrock is taken into account (Clark et al., 2006) does the weathering feedback help to reduce atmospheric pCO2 by about 10 ppm in 5000 years. Alley R.B. et al. (2005) Science 310, 456–460. Amiotte Suchet P. et al. (2003) Global Biogeochemical Cycles 17, 1139, doi:10.1029/2002GB001891. Clark P.U. et al. (2006) Quaternary Science Reviews 25, 3150–3184. [less ▲]

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See detailImpact of gender difference in hospital outcomes following percutaneous coronary intervention. Results of the Belgian Working Group on Interventional Cardiology (BWGIC) registry
LEMPEREUR, Mathieu ULg; Magne, Julien; Cornelis, Kristoff et al

in EuroIntervention : Journal of EuroPCR in Collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology (2014)

Aims: To determine whether there are gender-based differences in in-hospital outcomes among patients undergoing percutaneous coronary intervention (PCI). Methods and results: We studied a large cohort ... [more ▼]

Aims: To determine whether there are gender-based differences in in-hospital outcomes among patients undergoing percutaneous coronary intervention (PCI). Methods and results: We studied a large cohort using clinical data from a registry of 130,985 PCI procedures in Belgium, from January 2006 to February 2011. Compared to males, females were significantly older (70.3 vs. 64.8 years), and were more frequently diabetic or hypertensive. Men smoked more and more frequently had previous myocardial infarction (MI), previous PCI or previous coronary artery bypass graft (CABG) surgery. Coronary artery disease (CAD) was less severe in women, and PCI to the left anterior descending artery was more common in female patients. Unadjusted in-hospital mortality rates were higher in females versus males (2.5% for women and 1.6% for men, p<0.0001). After multivariable analysis, female gender remained an independent predictor of mortality (odds ratio 1.35, 95% CI: 1.22-1.49, p<0.0001). Conclusions: Gender-based differences in hospital mortality rates after PCI were observed in this large registry. Female sex remained an independent predictor of mortality after multivariable adjustment. [less ▲]

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See detailImpact of geomagnetic activity on high precision GNSS positioning. Galileo GALOCAD project
Warnant, René ULg; Bavier, Michaël; Lejeune, Sandrine et al

Conference (2006)

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See detailImpact of geometry and viewing angle on classification accuracy of 2D based analysis of dysmorphic faces
Vollmar, Tobias; Maus, Bärbel ULg; Wurtz, R. P. et al

in European Journal of Medical Genetics (2008), 51(1), 44-53

Digital image analysis of faces has been demonstrated to be effective in a small number of syndromes. In this paper we investigate several aspects that help bringing these methods closer to clinical ... [more ▼]

Digital image analysis of faces has been demonstrated to be effective in a small number of syndromes. In this paper we investigate several aspects that help bringing these methods closer to clinical application. First, we investigate the impact of increasing the number of syndromes from 10 to 14 as compared to an earlier study. Second, we include a side-view pose into the analysis and third, we scrutinize the effect of geometry information. Picture analysis uses a Gabor wavelet transform, standardization of landmark coordinates and subsequent statistical analysis. We can demonstrate that classification accuracy drops from 76% for 10 syndromes to 70% for 14 syndromes for frontal images. Including side-views achieves an accuracy of 76% again. Geometry performs excellently with 85% for combined poses. Combination of wavelets and geometry for both poses increases accuracy to 93%. In conclusion, a larger number of syndromes can be handled effectively by means of image analysis. [less ▲]

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See detailImpact of germline AIP mutations on tumor characteristics and Management in young acromegalic patients : results of an age-and tumor diameter matched cohort study
Tichomirowa, Maria A.; Theodoropoulou, Marily; Daly, Adrian ULg et al

in Abstract book - Endo 2011 (2011)

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See detailImpact of global climate change and desertification on the environment and society in Southern Centre of Vietnam (a case study in Binh Thuan province). Climate today and tomorrow: state of play and perception.
Ozer, Pierre ULg

Report (2012)

The Province of Binh Thuan is the driest area of Vietnam. It is felt as being affected by desertification processes that are mainly resulting from the ongoing „climate change‟, especially shortening ... [more ▼]

The Province of Binh Thuan is the driest area of Vietnam. It is felt as being affected by desertification processes that are mainly resulting from the ongoing „climate change‟, especially shortening rainfall. But has climate, and especially precipitations, really changed in recent years? Or is the recent increase of agricultural activities with higher water needs may explain such perception of a changing climate? In the collection of four papers presented hereafter, we try to answer to these questions. Yet, the first paper investigates recent trends in precipitation and temperatures using daily data from the weather station of Phan Thiet. It appears that the area did not experience any significant precipitation decrease (rainfall have, at the contrary, globally increased) but a very significant increase in temperature. The second paper focuses on future climate projections (that is 2046-2065 and 2081-2100 compared to historical data 1970-1999). It shows that the Province of Binh Thuan will face an increase of mean temperature of about 1.6°C (over 2046-2065) and 2.5°C (over 2081-2100) and an increase of extreme temperatures and extreme rainfall events. However, no significant changes about the evolution of the annual amount of precipitation were found. It also indicates that the dry season is likely to be longer in 2046-2065 owing to a delay in the onset of the rainy season (up to 15 days) accompanied by an earlier end of the rainy season (up to 30 days). The third paper explores recent land use and land cover changes in the Province of Binh Thuan. Comparisons of the land cover maps reveal that a steady growth in population has caused extensive changes of land cover throughout the area. The maps also indicate that the loss of woody land (forest) and the extension of irrigated area, combined with built-up encroachment, remains one of the most serious environmental problems today. Yet, results showed over the 12-year span, approximately 115,120 ha of forests were converted respectively to brush, irrigated area, cropland and built-up. This is an overall average decrease of approximately 9,594 ha of forested area per year. Based on the identified causes of these changes, we made policy recommendations for better management of land use and land cover. Such results show that water needs are always increasing due to the extension of irrigated areas. The last paper concludes with a case study of a fishing village disappearing as a result of shoreline erosion. It shows that the term “climate change” is misused probably because it is easier to blame a global issue rather than the local mismanagement of natural resources, the lack of land use planning and the nonexistence of policies focused on natural hazard management in the uncontrolled construction the seaside resort of Mui Ne. This reflexion about the wrong perception of climate change which may cause several economic problems could be extended to water availability which may not be sufficient to support recent developments of irrigated agriculture. Understanding current problems may help developing adaptation strategies in the next decades. Further research is needed to understand such perception of climate change, especially when knowing that future climate may be really affected by an increase of extreme rainfall events and an extended dry season. [less ▲]

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See detailImpact of global left ventricular afterload on left ventricular function in asymptomatic severe aortic stenosis: a two-dimensional speckle-tracking study.
Lancellotti, Patrizio ULg; Donal, Erwan; Magne, Julien ULg et al

in European Journal of Echocardiography (2010), 11(6), 537-543

Aims: The present study sought to assess the effect of global left ventricular (LV) afterload on LV myocardial systolic function in patients with aortic stenosis (AS) and preserved LV ejection fraction ... [more ▼]

Aims: The present study sought to assess the effect of global left ventricular (LV) afterload on LV myocardial systolic function in patients with aortic stenosis (AS) and preserved LV ejection fraction. <br />Methods and results: We prospectively examined the LV myocardial deformation (i.e. longitudinal, radial, and circumferential) by two-dimensional speckle tracking in 173 patients with asymptomatic severe AS. Thirty-eight patients (22%) had lowflow as determined by a low stroke volume index (􏰀35 mL/m2). By multivariable analysis, four variables emerged as independently associated with low-flow AS: peak Ea velocity (P 1⁄4 0.01), left atrial area index (P 1⁄4 0.017), global LV afterload (P 1⁄4 0.024), and circumferential myocardial deformation (P 1⁄4 0.04). Forty-nine patients (28%) had an increased global LV afterload (􏰁5 mmHg mL/m2). Systemic arterial compliance (P 1⁄4 0.001), circumferential myocardial deformation (P 1⁄4 0.024), and left atrial area index (P 1⁄4 0.04) were independently associated with increased global LV load in multivariable analysis. <br />Conclusion: In asymptomatic patients with severe AS, LV ejection fraction markedly underestimates the extent of myocardial sys- tolic impairment. Intrinsic myocardial dysfunction is particularly common in patients with increased global LV after- load, and especially in the subset of patients with low-flow AS. [less ▲]

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See detailImpact of glycerol and nitrogen concentration on Enterobacter A47 growth and exopolysaccharide production
Torres, Ch.; Marques, R.; Ferreira, A.R. et al

in International Journal of Biological Macromolecules (2014), 71

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See detailImpact of glycerol and storage temperature on gluatathione concentration and physiological state of Pseudomonas fluorescens BTP1 freeze-dried
Mputu Kanyinda, Jean-Noël ULg; Pierart, C.; Delvigne, Frank ULg et al

Poster (2012, February 15)

Pseudomonas fluorescens is commonly used as bio-fungicides in agriculture. For this use it requires formulations as either liquid or powder. Formulations have two advantages, storage and transport. Freeze ... [more ▼]

Pseudomonas fluorescens is commonly used as bio-fungicides in agriculture. For this use it requires formulations as either liquid or powder. Formulations have two advantages, storage and transport. Freeze-drying is a commonly used method to preserve bacteria. However, freeze-drying damages the cells, which results in loss of viability. Protective compounds are used to reduce loss of viability during process (freeze-drying and storage). In our study we used flow cytometry analysis to assess the physiological state in which cells are at the end of freeze-drying and Glutathione (GSH) was measured before and during storage. [less ▲]

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See detailImpact of GODAE products on nested HYCOM simulations of the West Florida Shelf
Halliwell, G. R.; Barth, Alexander ULg; Weiberg, R. H. et al

in Ocean Dynamics (2009), 59(1), 139-155

Nested non-assimilative simulations of the West Florida Shelf for 2004-2005 are used to quantify the impact of initial and boundary conditions provided by Global Ocean Data Assimilation Experiment ocean ... [more ▼]

Nested non-assimilative simulations of the West Florida Shelf for 2004-2005 are used to quantify the impact of initial and boundary conditions provided by Global Ocean Data Assimilation Experiment ocean products. Simulations are nested within an optimum interpolation hindcast of the Atlantic Ocean, the initial test of the US Navy Coupled Ocean Data Assimilation system for the Gulf of Mexico, and a global ocean hindcast that used the latter assimilation system. These simulations are compared to one that is nested in a non-assimilative Gulf of Mexico model to document the importance of assimilation in the outer model. Simulations are evaluated by comparing model results to moored Acoustic Doppler Current Profiler measurements and moored sea surface temperature time series. The choice of outer model has little influence on simulated velocity fluctuations over the inner and middle shelf where fluctuations are dominated by the deterministic wind-driven response. Improvement is documented in the representation of alongshore flow variability over the outer shelf, driven in part by the intrusion of the Loop Current and associated cyclones at the shelf edge near the Dry Tortugas. This improvement was realized in the simulation nested in the global ocean hindcast, the only outer model choice that contained a realistic representation of Loop Current transport associated with basin-scale wind-driven gyre circulation and the Atlantic Meridional Overturning Circulation. For temperature, the non-assimilative outer model had a cold bias in the upper ocean that was substantially corrected in the data-assimilative outer models, leading to improved temperature representation in the simulations nested in the assimilative outer models. [less ▲]

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See detailImpact of goldfish on terrestrial and aquatic microhabitat use in the palmate newt
Darnet, Elodie; Winandy, Laurane ULg; Denoël, Mathieu ULg

Poster (2014, December 12)

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See detailImpact of graft-versus-host disease after reduced-intensity conditioning allogeneic stem cell transplantation for acute myeloid leukemia : a report from the Acute Leukemia Working Party of the European group for blood and marrow transplantation
Baron, Frédéric ULg; Labopin, M.; Niederwieser, D. et al

in Leukemia : Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K (2012), 26(12), 2462-2468

This report investigated the impact of graft-versus-host disease (GVHD) on transplantation outcomes in 1859 acute myeloid leukemia patients given allogeneic peripheral blood stem cells after reduced ... [more ▼]

This report investigated the impact of graft-versus-host disease (GVHD) on transplantation outcomes in 1859 acute myeloid leukemia patients given allogeneic peripheral blood stem cells after reduced-intensity conditioning (RIC allo-SCT). Grade I acute GVHD was associated with a lower risk of relapse (hazards ratio (HR)¼0.7, P¼0.02) translating into a trend for better overall survival (OS; HR¼1.3; P¼0.07). Grade II acute GVHD had no net impact on OS, while grade III–IV acute GVHD was associated with a worse OS (HR¼0.4, Po0.0.001) owing to high risk of nonrelapse mortality (NRM; HR¼5.2, Po0.0001). In time-dependent multivariate Cox analyses, limited chronic GVHD tended to be associated with a lower risk of relapse (HR¼0.72; P¼0.07) translating into a better OS (HR¼1.8; Po0.001), while extensive chronic GVHD was associated with a lower risk of relapse (HR¼0.65; P¼0.02) but also with higher NRM (HR¼3.5; Po0.001) and thus had no net impact on OS. In-vivo T-cell depletion with antithymocyte globulin (ATG) or alemtuzumab was successful at preventing extensive chronic GVHD (Po0.001), but without improving OS for ATG and even with worsening OS for alemtuzumab (HR¼0.65; P¼0.001). These results highlight the role of the immune-mediated graft-versus-leukemia effect in the RIC allo-SCT setting, but also the need for improving the prevention and treatment of severe GVHD. [less ▲]

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See detailImpact of grazing by amphipods on the dynamics of the epiphytic cover of the Posidonia oceanica leaves : an in vitro experiment.
Michel, Loïc ULg; Gobert, Sylvie ULg; Dauby, Patrick ULg et al

Conference (2010, September 17)

It is now established that several species of amphipods associated to Mediterranean Posidonia oceanica meadows consume the epiphytes present on the leaves of the seagrass. However, little or no work has ... [more ▼]

It is now established that several species of amphipods associated to Mediterranean Posidonia oceanica meadows consume the epiphytes present on the leaves of the seagrass. However, little or no work has been undertaken to quantify this interaction. Here, we present the results of an in vitro experiment that used seagrass mimics to estimate the impact of grazing by the amphipods Apherusa chiereghinii, Dexamine spiniventris and Gammarus spp on the dynamics of the epiphytic cover. All species reduced epiphyte biomass in a significant way, and grazers preferentially fed on erected algae. Assimilation of epiphyte-derived carbon and nitrogen was monitored using stable isotopes (13C and 15N) labelling, and was obvious in the three taxa. Moreover, grazing activity of amphipods seemed to influence epiphyte physiology, notably by increasing nitrogen uptake by the erected algae. These results shed light on trophic interactions between the amphipods from Posidonia oceanica meadows and the seagrass epiphytic cover, and thus enhance our understanding of the role of these grazers in the functioning of the meadow as an ecosystem. [less ▲]

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See detailImpact of grazing by amphipods on the epiphytic cover of the Posidonia oceanica leaves: an in situ experiment.
Michel, Loïc ULg; Dupont, Alessandra; Gobert, Sylvie ULg et al

Poster (2010, October 22)

It is now established that several species of amphipods associated to Mediterranean Posidonia oceanica meadows consume the macro-epiphytes present on the leaves of the seagrass. Moreover, under controlled ... [more ▼]

It is now established that several species of amphipods associated to Mediterranean Posidonia oceanica meadows consume the macro-epiphytes present on the leaves of the seagrass. Moreover, under controlled in vitro conditions, three amphipod taxa (Apherusa chiereghinii,Dexamine spiniventris and Gammarus spp.) are able to drastically deplete the biomass of erected algae, thus influencing the epiphytic cover in both a quantitative and a qualitative way. Here, we tried to assess whether this strong and complex trophic interaction was realized in the field. We designed an in situ experiment that used microcosms placed directly in the meadow, at a depth of 10m, to estimate the impact of grazing by the aforementioned amphipod taxa on the dynamics of the epiphytic cover. Both Gammarus spp. and Dexamine spiniventris caused a significant decrease of the biomass of erected algae and erected animals (bryozoans and hydrozoans). Impact of grazing by Apherusa chiereghinii on these two epiphytic groups was less important, although strong but marginally non-significant (0,1>p>0,05) trends to lower biomasses were present. None of the considered taxa seemed to consume encrusting macro-epiphytes. In addition, assimilation of epiphyte-derived carbon and nitrogen by grazers was monitored using stable isotopes (13C and 15N), and epiphyte elemental content (C & N) was measured. Our results shed light on trophic interactions between the amphipods from Posidonia oceanica meadows and the seagrass epiphytic cover, and thus enhance our understanding of the role of these grazers in the functioning of the meadow as an ecosystem. [less ▲]

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See detailImpact of grazing on carbon balance of an intensively grazed grassland in Belgium
Jerome, Elisabeth ULg; Beckers, Yves ULg; Beekkerk van Ruth, Jöran ULg et al

Poster (2013, April 09)

This work analyzes the impact of grazing on the carbon balance of a grassland grazed by the Belgian Blue breed of cattle. The research was run at the Dorinne terrestrial observatory (DTO). The ... [more ▼]

This work analyzes the impact of grazing on the carbon balance of a grassland grazed by the Belgian Blue breed of cattle. The research was run at the Dorinne terrestrial observatory (DTO). The experimental site is a permanent grassland of ca. 4.2 ha located in the Belgian Condroz (50° 18’ 44’’ N; 4° 58’ 07’’ E; 248 m asl.). Other studies are conducted at the DTO including measurements of methane (CH4) and nitrous oxide fluxes (Dumortier et al., Geophysical Research Abstracts, Vol. 15, EGU2013-2083-1, 2013; Beekkerk van Ruth et al., Geophysical Research Abstracts, Vol. 15, EGU2013-3211, 2013, respectively). Grassland carbon budget (Net Biome Productivity, NBP) was calculated from Net Ecosystem Exchange (NEE) measured by eddy covariance by taking imports and exports of organic C and losses of carbon as CH4 into account (Soussana et al., 2010). After 2 years of measurements (May 2010 - May 2012), the grassland behaved on average as a CO2 source (NEE = 73 ±31 g C m-2 y-1). After inclusion of all the C inputs and outputs the site was closed to equilibrium (NBP = 23 ±34 g C m-2 y-1). To analyze the impact of grazing on CO2 fluxes, we studied the temporal evolution of gross maximal photosynthetic capacity GPPmax and dark respiration Rd (deduced from the response of daytime fluxes to radiation over 5-day windows). We calculated GPPmax and Rd variation between the end and the beginning of grazing or non-grazing periods (∆GPPmax and ∆Rd, respectively). We observed a significant decrease of GPPmax during grazing periods and measured a ∆GPPmax dependence on the average stocking rate. This allows us to quantify the assimilation reduction due to grass consumption by cattle. On the contrary, no Rd decrease was observed during grazing periods. Moreover, we found that cumulated monthly NEE increased significantly with the average stocking rate. In addition, a confinement experiment was carried out in order to analyze livestock contribution to Total Ecosystem Respiration. Each experiment extended over two days: the first day, cattle was confined in the footprint of the eddy covariance set-up (1.76 ha, 27 LU ha-1) and the second day, it was removed from it. We compared filtered half-hourly data made at 24h intervals, in the presence or absence of cattle, considering that environmental conditions were equivalent (air temperature, wind speed, radiation and wind direction). Results showed that CO2 fluxes were significantly higher when cattle were on the plot. Livestock contribution estimation to CO2 fluxes was on average 6.6 µmol m-2 s-1. [less ▲]

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See detailImpact of grazing on carbon dioxide exchanges in an intensively managed Belgian grassland
Jerome, Elisabeth ULg; Beckers, Yves ULg; Bodson, Bernard ULg et al

in Agriculture, Ecosystems & Environment (2014), 194

Given that the soil carbon (C) sequestration potential by grasslands can be used to partly mitigate the total greenhouse gas emissions of livestock production systems, a better understanding of the ... [more ▼]

Given that the soil carbon (C) sequestration potential by grasslands can be used to partly mitigate the total greenhouse gas emissions of livestock production systems, a better understanding of the effects of management practices, and especially grazing, on grassland carbon dioxide (CO2) exchanges has become a major concern. This study aimed at quantifying grazing impact on CO2 fluxes measured by eddy covariance by using innovative data analyses and experiments. For that, we distinguished direct and indirect grazing impact. Indirect impact results from biomass consumption, excretion deposits and soil compaction by cattle that modify CO2 exchanges. Direct impact results from livestock CO2 emissions through respiration that add to total ecosystem respiration. For the indirect impact, the variation during periods with fixed stocking rate of gross primary productivity at light saturation (GPPmax) and normalized dark respiration (Rd,10) was analyzed. On average, GPPmax decreased during grazing periods and increased during non-grazing periods which could be explained by aboveground biomass reduction and re-growth, respectively. In addition, GPPmax variations were negatively correlated to grazing intensity (defined as the product of the stocking rate and the grazing duration). On the contrary, no significant evolution of Rd,10 was found during both grazing and non-grazing periods, probably due to a combination of opposing effects of grazing on the total ecosystem respiration components. The direct impact was emphasized through four specific designed confinement experiments. Each experiment extended over three successive days. On the first and third day, there was no cattle on the plot, while, on the second day, cattle were confined in the main wind direction area of the eddy covariance set-up to increase the stocking rate (≈26livestockunitsha-1). The average livestock CO2 emissions during confinement, FCO2,livestock, were deduced from the differences between half-hourly measurements taken at 24h interval with or without cattle and under similar environmental conditions. They were estimated to be 2.59±0.58kgClivestockunit-1d-1 on average. This result was corroborated by independent estimates based on the C ingested by cattle during confinement. Using an annual average stocking of 2livestockunitsha-1, we found that livestock CO2 emissions represent only 8% of this grassland annual total ecosystem respiration. To our knowledge, this study is the first to quantify both direct and indirect livestock contribution to CO2 fluxes exchanged at the ecosystem scale using the eddy covariance technique. © 2014 Elsevier B.V. [less ▲]

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See detailImpact of grazing on carbon dioxide flux exchanges in an intensively managed grassland
Jerome, Elisabeth ULg; Beckers, Yves ULg; Bodson, Bernard ULg et al

Poster (2013, September)

To date, there are few studies assessing the impact of specific management events, particularly grazing, on carbon (C) and carbon dioxide (CO2) fluxes in managed grasslands. Grazing effects are indeed ... [more ▼]

To date, there are few studies assessing the impact of specific management events, particularly grazing, on carbon (C) and carbon dioxide (CO2) fluxes in managed grasslands. Grazing effects are indeed difficult to discern. They vary with the stocking rate and the length of the grazing period. Moreover, they are often masked by environmental responses. The aim of the present study was to assess the impact of grazing on the CO2 fluxes of a grassland grazed by the Belgian Blue breed of cattle. The research was run at the Dorinne Terrestrial Observatory (DTO), located in the Belgian Condroz (50° 18’ 44’’ N; 4° 58’ 07’’ E; 248 m asl.). The site is a permanent grassland of ca. 4.2 ha subjected to intensive management. Grassland carbon budget at the system boundaries is calculated from Net Ecosystem Exchange of CO2 measured by eddy covariance by taking imports and exports of organic C and losses of carbon as methane into account. After 2 years of measurements, the site was close to equilibrium. If management practices (harvest, fertilization and imports as supplementary feedings) and climatic conditions had a significant impact on the C balance, the impact of grazing was uncertain, especially on CO2 fluxes. To do this analysis, we distinguished the long term and the short term impacts of grazing on CO2 fluxes. The long term effect results from the biomass consummation by the cattle and from the cattle effluents that modify assimilation and respiration fluxes. This could be quantified only by comparing fluxes before and after grazing periods. The short term impact is due to cattle respiration that is a part of total ecosystem respiration and should be measured in its presence in the field. For the long term effects of grazing on CO2 fluxes, we analyzed the temporal evolution of gross maximal photosynthetic capacity GPPmax and dark respiration normalized at 10°C (Rd,10). Those parameters were deduced from the response of daytime CO2 fluxes to radiation over 5-day windows. We calculated parameters variations between the beginning and the end of grazing and non-grazing periods (∆GPPmax, ∆Rd,10) and analyzed their dependence to stocking rate. We found a significant decreased of ∆GPPmax that allowed us to quantify the assimilation reduction due to grass consumption by cattle. Discrimination of this impact from flux response to climate was possible only after gathering and treating two years of measurements taken under various climatic conditions. At the opposite, no significant evolution of Rd,10 with the average stocking rate was found. The short term impacts were an increase of CO2 fluxes in presence of cattle. It could be distinguished and quantified only thanks to confinement experiments. Each experiment extended over two days: the first day, cattle was confined in the footprint of the eddy covariance set-up (1.76 ha, 27 LU ha-1) and the second day, it was removed from it. We compared filtered half-hourly data made at 24h intervals, in the presence or absence of cattle, considering that environmental conditions were equivalent (air temperature, wind speed, radiation and wind direction). Livestock contribution to CO2 fluxes was estimated to be 2.25 ± 0.68 kg C LU-1 d-1. [less ▲]

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