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See detailAssessing the impacts of present and future interannual climate variability on European ecosystems using a dynamic vegetation model
Dury, Marie ULg; Hambuckers, Alain ULg; Warnant, Pierre et al

Poster (2011, April)

Climate projections indicate changes in mean climate as well as in climate variability and frequency of extreme events for the end of the 21st century compared to present. Since many biological processes ... [more ▼]

Climate projections indicate changes in mean climate as well as in climate variability and frequency of extreme events for the end of the 21st century compared to present. Since many biological processes reach non-reversible thresholds (loss of ability to germinate, mortality, etc.) at some temperatures or soil water values, changes in climate variability have long-term consequences for ecosystem composition, functioning and carbon storage. The CARAIB dynamic vegetation model is used to evaluate and analyse how future climate variability will affect European ecosystems. We examine the impacts of climate change and associated drought episodes on primary productivity (NPP) as well as on fire intensity. CARAIB is driven by the ARPEGE/Climate model and three regional climate models from the European Union project ENSEMBLES (KNMI-RACMO2, DMI-HIRHAM5 and HC-HadRM3Q0 models) forced with the IPCC A1B emission scenario. We analyse the interannual climate variability simulated by those climate models and compare it with the observed climate variability (CRU TS 3.0 historical climate dataset) over the period 1961-1990. None of these climate models can reproduce accurately the present natural climate variability. Therefore, the present NPP interannual variability simulated by CARAIB using climate outputs from the climate models differs from the one obtained with observed climate. For instance, the NPP interannual variability obtained with the ARPEGE/Climate model is significantly overestimated in some parts of Europe, especially in the Mediterranean region, in France, in northern Germany and northern Poland, in the Balkans and in Ukraine. Since discrepancies between modelled and observed current climate variability may also affect NPP variability calculated for the future as well as the intensity and the frequency of severe drought periods and wildfires, comparing the terrestrial ecosystem evolutions obtained with a range of climate models allows to improve the assessment of climate change impacts on ecosystems in the future. Anyway the trend between the present and the future is expected to be more robust. The NPP interannual variability increases in the future with the four climate models as a result of more frequent and more severe soil water stress episodes in southern and Central Europe. The projected climate changes are also likely to induce increased fire risk in the Mediterranean region but also in Central Europe and Russia. [less ▲]

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See detailResponses of European forest ecosystems to 21(st) century climate: assessing changes in interannual variability and fire intensity
Dury, Marie ULg; Hambuckers, Alain ULg; Warnant, P. et al

in iForest: Biogeosciences and Forestry (2011), 4

Significant climatic changes are currently observed and, according to projections, will be strengthened over the 21(st) century throughout the world with the continuing increase of the atmospheric CO2 ... [more ▼]

Significant climatic changes are currently observed and, according to projections, will be strengthened over the 21(st) century throughout the world with the continuing increase of the atmospheric CO2 concentration. Climate will be generally warmer with notably changes in the seasonality and in the precipitation regime. These changes will have major impacts on the biodiversity and the functioning of natural ecosystems. The CARAIB dynamic vegetation model driven by the ARPEGE/Climate model under forcing from the A2 IPCC emission scenario is used to illustrate and analyse the potential impacts of climate change on forest productivity and distribution as well as fire intensity over Europe. The potential CO2 fertilizing effect is studied throughout transient runs of the vegetation model over the 1961-2100 period assuming constant and increasing atmospheric CO2 concentration. Without fertilisation effect, the net primary productivity (NPP) might increase in high latitudes and altitudes (by up to 40 % or even 60-100 %) while it might decrease in temperate (by up to 50 %) and in warmer regions, e.g., Mediterranean area (by up to 80 %). This strong decrease in NPP is associated with recurrent drought events occurring mostly in summer time. Under rising CO2 concentration, NPP increases all over Europe by as much as 25-75%, but it is not clear whether or not soils might sustain such an increase. The model indicates also that interannual NPP variability might strongly increase in the areas which will undergo recurrent water stress in the future. During the years exhibiting summer drought, the NPP might decrease to values much lower than present-day average NPP even when CO2 fertilization is included. Moreover, years with such events will happen much more frequently than today. Regions with more severe droughts might also be affected by an increase of wildfire frequency and intensity, which may have large impacts on vegetation density and distribution. For instance, in the Mediterranean basin, the area burned by wildfire can be expected to increase by a factor of 3-5 at the end of the 21(st) century compared to present. [less ▲]

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See detailResponse of the European forests to extreme climatic events predicted for the 21st century: sensitivity to climate models and their variability
Dury, Marie ULg; Hambuckers, Alain ULg; Warnant, Pierre et al

Conference (2010, October)

Significant climatic changes are currently observed and, according to projections, will be strengthened over the 21st century throughout the world with the enhanced greenhouse effect. Climate will be ... [more ▼]

Significant climatic changes are currently observed and, according to projections, will be strengthened over the 21st century throughout the world with the enhanced greenhouse effect. Climate will be generally warmer with notably changes in the seasonality and in the precipitation regime. The CARAIB dynamic vegetation model is used to evaluate and analyse the potential impacts of climate change on forests ecosystems in Europe. Changes in the hydrological budget as well as in the intensity and the frequency of wildfires and their effects on forest productivity and distribution are especially assessed. CARAIB is driven by the ARPEGE-Climat model and some other regional climate models from the European Union (EU) project ENSEMBLES forced with IPCC A1B emission scenario. Climate projections indicate changes in variability and frequency of extreme events. Since climate variability governs the response of plant species (e.g. net primary productivity, NPP) to climate change, we analyse the climate variability (seasonal and interannual) given by climate models comparing it with the observed climate variability (CRU TS 3.0 historical climate dataset) over the period 1961-1990. The variability modelled by the ARPEGE-Climat model is notably slightly more pronounced than the observed one, at least for some areas. Since discrepancies between modelled and observed current climate variability may affect NPP variability calculated for the future as well as the intensity and the frequency of severe drought period and wildfires, comparing the forest ecosystem evolutions obtained with a range of climate models allows improving the assessment of climate change impacts on forest in the future. [less ▲]

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See detailResponse of the European ecosystems to climate change: a modelling approach for the 21st century
Dury, Marie ULg; Warnant, Pierre; François, Louis ULg et al

Poster (2010, May)

According to projections, over the 21st century, significant climatic changes appear and will be strengthened all over the world with the continuing increase of the atmospheric CO2 level. Climate will be ... [more ▼]

According to projections, over the 21st century, significant climatic changes appear and will be strengthened all over the world with the continuing increase of the atmospheric CO2 level. Climate will be generally warmer with notably changes in the seasonality and in the precipitation regime. These changes will have major impacts on the environment and on the biodiversity of natural ecosystems. Geographic distribution of ecosystems may be modified since species will be driven to migrate towards more suitable areas (e. g., shifting of the arctic trees lines). The CARAIB dynamic vegetation model (Carbon Assimilation in the Biosphere) forced with 21st century climate scenarios of the IPCC (ARPEGE-Climat model) is used to illustrate and analyse the potential impacts of climate change on tree species distribution and productivity over Europe. Changes in hydrological budget (e. g., runoff) and fire effects on forests will also be shown. Transient runs (1975-2100) with a new dynamic module introduced in CARAIB are performed to follow the future evolutions. In the new module, the processes of species establishment, competition and mortality due to stresses and disturbances have been improved. Among others, increased atmospheric CO2 and warmer climate increase tree productivity while drier conditions decrease it. Regions with more severe droughts will also be affected by an increase of wildfire frequency, which may have large impacts on vegetation density and distribution. [less ▲]

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See detailProblem of applying sodium selenate to increase selenium concentrations in grassland plant in Southern Belgium
Hambuckers, Alain ULg; Dotreppe, Olivier ULg; Istasse, Louis ULg

in Communications in Soil Science & Plant Analysis (2010), 41

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See detailMeasuring home-range quality in the frugivorous gibbon (Hylobates lar)
Hambuckers, Alain ULg; Huynen, Marie-Claude ULg; Savini, Tommaso

Conference (2009)

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See detailNutrient digestibility of Mucuna (Mucuna pruriens var. utilis) bean in guinea fowl (Numida meleagris, L): Effects of heat treatment and levels of incorporation in diets.
Dahouda, M.; Toleba, S. S.; Youssao, A. K. I. et al

in British Poultry Science (2009), 50(5), 564-72

1. Mucuna pruriens var. utilis is a legume, the seeds of which are scarcely used in animal diets owing to their high content of 3,4-dihydroxy-L-phenylalanine (L-Dopa). 2. Experiments were conducted on ... [more ▼]

1. Mucuna pruriens var. utilis is a legume, the seeds of which are scarcely used in animal diets owing to their high content of 3,4-dihydroxy-L-phenylalanine (L-Dopa). 2. Experiments were conducted on guinea fowl to assess the effects of two types of heat processing (cooking and toasting) on chemical composition and nutrient digestibility of Mucuna seeds offered alone or incorporated at three concentrations (40, 120 or 200 g/kg) in complete diets. 3. Diets containing 200 g/kg seeds had more crude fibre and less ether extract. L-Dopa content increased with the amount of Mucuna inclusion. Cooking reduced markedly L-Dopa content while toasting had no effect. When fed alone, Mucuna seeds dramatically decreased feed intake. 4. Feed intake (FI) and body weight gain (BWG) were not influenced by the complete diets. Cooking significantly increased crude fibre digestibility. 5. It is suggested that cracked and cooked Mucuna bean can be incorporated at a safe level of 120 g/kg in complete diets for guinea fowl production. [less ▲]

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See detailFood resources unconventional use for poultry production in Africa: nutritional values and constraints
Dahouda, M.; Toleba, S. S.; Senou, M. et al

in Annales de Médecine Vétérinaire (2009), 153(1), 5-21

Numerous works are related to the use of unconventional feed resources, and particularly to Mucuna Spp., in poultry diet. This review aims at describing the context of their use, their nutritional values ... [more ▼]

Numerous works are related to the use of unconventional feed resources, and particularly to Mucuna Spp., in poultry diet. This review aims at describing the context of their use, their nutritional values and the constraints related to their upgrading, before considering the effects of the various methods of treatment on the reduction of the toxic substances that they could contain and on their chemical compositions. The methods of treatment are very variable and their standardisation should allow using them in rural area. Those feed could thus constitute an alternative to costly conventional feed usually used in poultry production. [less ▲]

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See detailLes ressources alimentaires non-conventionnelles utilisables pour la production aviaire en Afrique : valeurs nutritionnelles et contraintes
Dahouda, M.; Toléba, S. S.; Sénou, M. et al

in Annales de Médecine Vétérinaire (2009), 153

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See detailThe effects of raw and processed Mucuna priurens seed based diets on the growth parameters and meat characteristics of Benin local Guinea fowl (Meleagris numida, L)
Dahouda, M.; Toleba, S. S.; Youssao, A. K. I. et al

in International Journal of Poultry Sciences (2009), 8(9), 882-889

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See detailSoil-applied selenium effects on tissue selenium concentrations in cultivated and adventitious grassland and pasture plant species
Hambuckers, Alain ULg; Dotreppe, Olivier ULg; Hornick, Jean-Luc ULg et al

in Communications in Soil Science & Plant Analysis (2008), 39(5-6), 800-811

According to international nutritional standards, plant selenium (Se) concentrations in Belgium are too low. To correct this situation, adding Se in fertilizers for pastures and grasslands is suggested ... [more ▼]

According to international nutritional standards, plant selenium (Se) concentrations in Belgium are too low. To correct this situation, adding Se in fertilizers for pastures and grasslands is suggested, similar to activities in Finland. However, there is a lack of data on meadow plant species' ability to absorb Se. Therefore, a pot experiment was initiated using 24 meadow plant species cultivated on a Belgian cambisol receiving standard fertilizer treatment, with or without the addition of 9 g Se ha(-1) yr(-1) as sodium selenate. Soil Se analysis confirmed the low Se status of the native soil. Mean foliar Se concentration in the control group was 0.05 mg kg(-1). Because plant deficiency may occur at levels less than 0.10 mg Se kg(-1), data provided further evidence for Se deficiency in Belgium plant production. When grown with Se, plant species showed wide variations for Se concentration, ranging from 0.08 to 0.49 mg Se kg(-1). All values were less than 2 mg Se kg(-1), the suggested threshold toxicity level for dairy cattle. There were two different types of plants in terms of response to Se fertilization. Most of the tested plants were known as nonaccumulators. There were also two probable secondary accumulators: Sinapis arvensis and Melilotus albus. Finally, one has to question the reliability of plant Se enhancement using this method when floristic composition is poorly controlled. [less ▲]

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See detailSeasonal variations in the crop contents of scavenging Helmeted Guinea Fowls (Numida meleagris, L.) in Parakou (Benin).
Dahouda, M.; Toléba, Seibou Soumanou; Youssao, A. K. I. et al

in British Poultry Science (2008), 49(6), 751-9

1. An experiment was carried out with 120 helmeted guinea fowls during one year in Parakou (Benin). Feed intake, ingredient and chemical composition, along with the nutritional adequacy of scavenging ... [more ▼]

1. An experiment was carried out with 120 helmeted guinea fowls during one year in Parakou (Benin). Feed intake, ingredient and chemical composition, along with the nutritional adequacy of scavenging diets were measured during the rainy season (November-February) and dry season (March-October) in order to propose supplementation strategies. Ingredients found in crops were identified and allocated into 6 main categories (supplemental feed, seeds, green forages, animal materials, mineral matter and unidentified materials). 2. Mean dry weights of crop contents were significantly higher in the rainy than in the dry season. Amounts and proportions of supplemental feed and seeds were not significantly different between seasons, whereas those of green forage, animal materials and mineral matter were higher in rainy season. Supplemental feed, especially maize and sorghum, was the largest component of the crop content in both seasons. The most represented grass seeds were Panicum maximum (rainy season) and Rottboellia cochinchinensis (dry season). 3. Dietary concentrations of organic matter, non-nitrogen extract and metabolisable energy were higher in the dry season, while mineral concentrations were higher in the rainy season. There were no significant differences between the two seasons in dry matter, crude protein or crude fibre. 4. Scavenging provided insufficient nutrients and energy to allow guinea fowls to be productive. Therefore, more nutritionally balanced supplementary feed would be required during both seasons. [less ▲]

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See detailBiodiversité
Hambuckers, Alain ULg

in Marbaix, P.; van Ypersele, J.-P. (Eds.) Imapcts des changements climatiques en Belgique (2004)

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See detailBiodiversiteit
Hambuckers, Alain ULg

in Marbaix, P.; van Ypersele, J.-P. (Eds.) Impacts van de klimaatveranderingen in België (2004)

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See detailProduction of selenium-enriched grass and haylage by mineral fertilisation in southern Belgium
de Behr, V.; Coenen, M.; Hambuckers, Alain ULg et al

in Proceedings of 7th Conference of the European Society of Veterinary and Comparative Nutrition (2003)

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See detailWatershed Liming in the Belgian Ardennes : Effects on soil solution and streamwater chemistry
Carnol, Monique ULg; Hambuckers, Alain ULg; Remacle, Jean ULg

Conference (1997, June)

Forest liming has received increased attention in the 1980s, when unusual needle yellowing and fall were observed in large parts of Europe and North America. This ‘new forest decline’ has been attributed ... [more ▼]

Forest liming has received increased attention in the 1980s, when unusual needle yellowing and fall were observed in large parts of Europe and North America. This ‘new forest decline’ has been attributed to several causes acting individually or synergetically, amongst which were acidification, N saturation and nutritional imbalances. This time, liming did not aim at increased productivity, but as a counteracting measure to the soil acidification and to remove nutritional imbalances. The Belgian Ardennes were not exempt from this phenomena and symptoms of forest dieback were reported in 1983 by Weissen (Weissen et al.,1983). Soils are naturally poor in magnesium and the observed dieback was supposed to be the consequence of increased pollution exacerbating the deficiency in magnesium. A reduction in productivity and financial losses were predicted. Liming was suggested for prevention and correction, however possible side effects, in particular on soil solution (tree nutrition) and stream water chemistry (drinking water) needed to be evaluated. In this paper, we present results from a case study in four Picea abies watersheds in southern Belgium. The paired watersheds of approximately 80 ha were situated in the ‘Haute Ardenne’ and in the ‘Ardenne occidentale’ regions, on acid brown soils. One watershed of each pair was limed with 3 T/ha of fine ground dolomite ((Ca,Mg)CO3) 55/40 and 200 kg/ha K2SO4 in 1992 and 1993, respectively. Rainfall, throughfall and monolith lysimeter soil solution were analysed at monthly intervals, and runoff chemistry at two-weekly intervals (volume-weighed reconstructed daily samples). Time series intervention analysis was used as a tool to detect statistically significant changes in stream water chemistry due to the liming event, and fluxes were calculated to evaluate losses of the applied dolomitic lime to the catchment stream. Dolomite dissolution distinctively affected streamwater chemistry in the watershed situated in the Hautes Ardennes (Waroneu). Magnesium concentrations increased immediately after liming, most likely due to surface runoff. Four years after liming, concentrations were still higher than prior to liming. However, the proportions of magnesium lost were relatively low compared to the dose applied. Calcium concentrations did not change after liming in either catchment, nor did the concentrations of the major cations and anions measured. In the monolith lysimeters, magnesium concentrations increased immediately after liming under the organic horizons, and one year after liming under the mineral horizons. Calcium concentrations increased only three years after the application of lime under the organic and mineral horizons. These results led to the conclusions that for the soils under study and the doses applied, a major part of the lime was retained by the soil system, and that consequences on water chemistry were minor. [less ▲]

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See detailTrace metal transfers between water and sediment in a freshwater system. Influence of microbial activity
Hambuckers-Berhin, Françoise; Hambuckers, Alain ULg; Remacle, Jean

in Studies in Environmental Science (1997), 68(353-368),

The purpose of our work was to determine, in a freshwater batch system, the importance and the direction of trace metal transfers between sediment and water as influenced by bacterial activity. Sediment ... [more ▼]

The purpose of our work was to determine, in a freshwater batch system, the importance and the direction of trace metal transfers between sediment and water as influenced by bacterial activity. Sediment was incubated in Meuse water in different conditions. Net transfer occurred on an average from sediment to water for Co, Cs, Cr, Cu, Hg, La, Ni, Zn and from water to sediment for Bi, Cd, Pb, Sb, Tl. Positive correlations between oxygen consumption and transfer of nine metals from sediment to water demonstrate the influence of bacterial activity. Correlations of the metal transfer either with water pH or with the variation of sediment weight at the end of incubation led to suppose that the alteration of the chemical conditions also strongly influenced the transfers. It was confirmed by the comparison of chemical characteristics of the water and of the sediment at the end of incubation in contrasted conditions. The uptake of 12 metals by a bacterial community isolated from the sediment was related to metal concentrations in the water. The specific transfer from the water to the bacterial biomass was appraised in the sediment incubation experiments. It allowed to compute the net metal transfer of 12 metals from the sediment to the water with significant bacterial activity. The comparison of these values with the transfers occurring at 4°C, i.e. with reduced bacterial activity, demonstrated that the transfer of 11 metals from the sediment to the water is clearly enhanced by bacterial activity. [less ▲]

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See detailIS THE PRESENCE OF MESOTROPHIC PLANT-COMMUNITIES IN THE PEAT-BOGS OF HAUTES-FAGNES (BELGIUM) CONNECTED WITH TONALITE INTRUSIONS IN THE REVINIAN LAYERS
Hambuckers, Alain ULg; Schumacker, René ULg; Remacle, Jean ULg et al

in Belgian Journal of Botany (1995), 128(1), 48-56

Within the Hautes-Fagnes Nature Reserve (Belgium) acidic and oligotrophic biotopes are developing on very acidified stony silt raised bogs. However, they are locally dominated by mesotrophic species ... [more ▼]

Within the Hautes-Fagnes Nature Reserve (Belgium) acidic and oligotrophic biotopes are developing on very acidified stony silt raised bogs. However, they are locally dominated by mesotrophic species. Based on the fact that there are several outcrops of tonalite in the region and particularly one in the Nature Reserve, a hypothesis to explain these singularities of the vegetation implies discontinuities of the bedrock provoked by intrusions of this magmatic rock in the Revinian layer covering the region. Seventeen plots containing Phragmites australis were examined and vegetation was described. Silt and soil water were sampled and analyzed for mineral contents in 15 sites. The differences of mineral composition between the P. australis plots and their surrounding environment confirmed the more mesotrophic characteristics of these plots (i.e. higher pH, higher Ca and Mg contents, lower Al content). However, the lower Zn, Pb and Fe contents would lead to reject the hypothesis of intrusions of tonalite since these elements are more abundant in the tonalite and its mineralization than in the Revinian rock. Nevertheless, the overall ecological conditions of the examined plots and the differences of plant species composition suggested that the observed chemical environment could be evoked for explaining the distribution of the mesotrophic species in the oligotrophic environment of the Nature Reserve. Consequently, an alternative hypothesis is proposed. [less ▲]

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See detailThe role of the bacterial community in the radionuclide transfers in freshwater ecosystems
Hambuckers-Berhin, Françoise; Hambuckers, Alain ULg; Remacle, Jean ULg

in Studies in Environmental Science (1993), 55(337-353),

This chapter investigates the radionuclide fluxes between the bacteria and the water in aquatic ecosystem by examining the bulk transfers mediated by a bacterial community isolated from the river ... [more ▼]

This chapter investigates the radionuclide fluxes between the bacteria and the water in aquatic ecosystem by examining the bulk transfers mediated by a bacterial community isolated from the river sediments. A comparison of the aerobic bacterial communities colonizing the sediments and the water column shows that the bacterial community of the sediments is composed of two sub-communities. The first one is similar to the water column community by its biochemical features; the other one displays quite different characteristics and appears to be more representative of the sediments. An important part of 60Co and 134Cs can be immobilized by the bacterial biomass that constitutes a pool of radionuclides, their transfers to the water column being controlled by temperature and pH. The uptake of 60Co and 134Cs by bacteria is described by the Michaelis–Menten model. The uptake kinetics depend on the type of radionuclide and the level of radiocontamination in the water column. The highest affinity uptake system is observed for 60Co at low radiocontamination levels. The decontamination of bacterial biomass develops in two phases. The first phase is characterized by a very short biological half-life, a few seconds or minutes, while the second phase is longer; the biological half-lives reach between 15 h to 461 h for 60Co and between 39 h and 8,976 h for 134C [less ▲]

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