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See detailPredicting the future of an endemic endangered Andean bird species with a niche-based-model nested into a dynamic vegetation model
Hambuckers, Alain ULg; Zuniga, Lilian; Dury, Marie ULg et al

Conference (2017, February 05)

The slopes of the Andes are recognized as supporting the highest avian diversity in the world combined with high endemism rate but also more than 20 % of threatened species. Frugivores birds, even rare ... [more ▼]

The slopes of the Andes are recognized as supporting the highest avian diversity in the world combined with high endemism rate but also more than 20 % of threatened species. Frugivores birds, even rare species, are known as major providers of seed dispersal service. In Bolivia, the large Red-fronted Macaw (Ara rubrogenys Lafresnaye, 1847) is one of the 15 endemic species of this country. Its natural habitat is mainly semi-deciduous dry forest but this habitat is most often severely degraded. Climate change is an additional threat over tropical mountain birds and this particular species, since some scenarios suggest warming as high as 7.5°C by 2080 and significant variations in the precipitation regime and available soil water. To infer the future of bird species under warming climate, many authors use niche-based models (NBM), in which they combine effects of climate variables, alone or in combination with other environmental variables. A more elaborated approach consists in also including biotic interactions, notably the availability of particular plant species. While NBM with climate variables are now considered as a standard method to predict plant species distribution under future climate, this approach fails to consider the effect of increasing CO2 concentration in air on plant physiology. Contrariwise, dynamic vegetation models (DVM) are commonly able to reproduce this effect, although the uncertainties on the CO2 are large. This study assesses the potential impact of climate change on the range of A. rubrogenys, by combining within a NBM climate variables, relief and biotic variables, i.e. plant species resource. Plant resource is computed with a DVM and a NBM to compare the methodologies and to evaluate potential effects of CO2 on plant species distribution and indirect impacts on the bird. [less ▲]

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See detailUsing a dynamic vegetation model for future projections of crop yields: simulations from the plot scale to the Belgian and European scales
Jacquemin, Ingrid ULg; Dury, Marie ULg; Henrot, Alexandra-Jane ULg et al

Conference (2016, September 29)

Dynamic vegetation models (DVM), such as CARAIB (“CARbon Assimilation In the Biosphere”) were initially designed to describe the dynamics of natural ecosystems as a function of climate and soil with the ... [more ▼]

Dynamic vegetation models (DVM), such as CARAIB (“CARbon Assimilation In the Biosphere”) were initially designed to describe the dynamics of natural ecosystems as a function of climate and soil with the aim of studying the role of vegetation in the carbon cycle. But their characteristics allow numerous other applications and improvements, such as the development of a crop module. This module can be validated at the plot scale, with the use of eddy-covariance data from agricultural sites in the FLUXNET network. The carbon fluxes (e.g., net ecosystem exchange (NEE), gross primary productivity (GPP)) and the evapotranspiration (ET) simulated with the CARAIB model are compared with the fluxes measured at several sites, in order to cover a maximum number of crop types (winter wheat/barley, sugar beets, potatoes, rapeseed,…) and to evaluate the model for different European regions (Belgium, France, Germany,…). The aim of this validation is to assess the model ability to reproduce the seasonal and inter-annual variability of carbon fluxes. In order to assess the spatial variability of the model, CARAIB will be applied over Belgium and forced with the outputs the regional climate model ALARO (4 km resolution), for the recent past and the decennial projections. To reach the larger scale, we also aim to assess crops yields over Europe and to quantify the uncertainties in the climatic projections. CARAIB will be driven with the outputs of different regional climatic models (RCMs), nested in CMIP5 GCM projections for the EURO-CORDEX project: ALADIN53 (Météo-France/CNRM), RACMO22E (KNMI), RCA4 (SMHI) and REMO2009 (MPI-CSC) RCMs. These climatic projections are at a high spatial resolution (0.11-degree, ≈12 km). The model will be set up for the most common crops in Europe and for simulations tests with marginal and/or new crops. Finally, this simulation ensemble will be used to highlight potential changes in the most productive areas of Europe. [less ▲]

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See detailAssessing the impact of climate change on terrestrial plants in Europe using a Dynamic Vegetation Model driven by EURO-CORDEX projections
Dury, Marie ULg; Hambuckers, Alain ULg; Henrot, Alexandra-Jane ULg et al

Poster (2016, September 26)

While the combination of warmer and drier mean climatic conditions can have severe impacts on ecosystems, extreme events like droughts or heat waves that break the gradual climate change can have more ... [more ▼]

While the combination of warmer and drier mean climatic conditions can have severe impacts on ecosystems, extreme events like droughts or heat waves that break the gradual climate change can have more long-term consequences on ecosystem composition, functioning and carbon storage. Hence, it is essential to assess the changes in climate variability and the changes in frequency of extreme events projected for the future. Here, the process-based dynamic vegetation model CARAIB DVM was used to evaluate and analyse how future climate and extreme events will affect European terrestrial plants. To quantify the uncertainties in climatic projections and their potential impacts on ecosystems, the vegetation model was driven with the outputs of different regional climatic models, nested in CMIP5 GCM projections for the EURO-CORDEX project: ALADIN53 (Météo-France/CNRM), RACMO22E (KNMI), RCA4 (SMHI) and REMO2009 (MPI-CSC) RCMs. These daily climatic scenarios are at a high spatial resolution (0.11°, ≈ 12 km). CARAIB simulations were performed across Europe over the historical period 1971-2005 and the future period 2006-2100 under RCP4.5 and RCP8.5 emission scenarios. We simulated a set of 99 individual species (47 herbs, 12 shrubs and 40 trees) representing the major European ecosystem flora. First, we analysed the climatic variability simulated by the climatic models over the historical period and compared it with the observed climatic variability. Then, we evaluated change in climatic variability and extreme events projected by the climatic models for the end of the century. Finally, we assessed the change in species productivity and abundance. We evaluated the severity of projected productivity change for the period 2070-2099 relative to their current productivity variability (period 1970-1999). Mean changes were considered severe if they exceed observed variability. The projections of potential shifts in species distributions are directly dedicated to current forest management. [less ▲]

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See detailFruit biomass availability along a forest cover gradiant
Pessoa; Rocca, Larissa; Talora, Daniela et al

in Biotropica (2016), doi:10.1111/btp.12359

Habitat loss is the main driver of the current high rate of species extinction, particularly in tropical forests. Understanding the factors associated with biodiversity loss, such as the extinction of ... [more ▼]

Habitat loss is the main driver of the current high rate of species extinction, particularly in tropical forests. Understanding the factors associated with biodiversity loss, such as the extinction of species interactions and ecological functions, is an urgent priority. Here, our aim was to evaluate how landscape-scale forest cover influences fruit biomass comparing different tree functional groups. We sampled 20 forest fragments located within landscapes with forest cover ranging from 2 to 93 percent in the Atlantic Forest of southern Bahia, Brazil. In each fragment, we established five plots of 25 × 4 m and carried out phenological observations on fleshy fruit throughout one year on all trees ≥ 5 cm dbh. We estimated fruit availability by direct counting all fruits and derived fruit biomass from this count. We used spatial mixed linear models to evaluate the effects of forest cover on species richness, abundance, and fruit biomass. Our results indicated that forest cover was the main explanatory variable and negatively influenced the total richness and abundance of zoochoric and shade-tolerant but not shade-intolerant species. A linear model best explained variations in richness and abundance of total and shade-tolerant species. We also found that forest cover was positively correlated with the fruit biomass produced by all species and by the shade-tolerant assemblages, with linear models best explaining both relationships. The loss of shade-tolerant species and the lower fruit production in fragments with lower landscape-scale forest cover may have implications for the maintenance of frugivore, seed dispersal service, and plant recruitment. [less ▲]

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See detailInfluence of frugivore taxa on the generation of plant recruitment foci and on the composition of plant recruits’ communities
Trolliet, Franck ULg; Forget, Pierre-Michel; Doucet, Jean-Louis ULg et al

Conference (2016, June 20)

Frugivores can disperse seeds in a spatially contagious pattern and generate recruitment foci (e.g. under fruiting trees). This process is increasingly explored to understand the influence of frugivores ... [more ▼]

Frugivores can disperse seeds in a spatially contagious pattern and generate recruitment foci (e.g. under fruiting trees). This process is increasingly explored to understand the influence of frugivores on the spatial organization of plant communities, and can also serve as a method to efficiently monitor the consequences of animal extirpation. However, there is limited evidence contrasting the influence of different frugivores taxa on the creation of recruitment foci under fruiting trees, and, similarly, on the overall composition of plant communities. Here, we aimed (i) to compare the role of hornbills and primates in creating recruitment foci, and (ii) to investigate how the presence of hornbills, primates and elephants influence the overall composition of plant recruit’s community in an anthropized forest-savanna mosaic in DR Congo. We firstly compared the community of recruits (0.5-2 m high) in 25-m² plots below hornbill-dispersed trees (Staudtia kamerunensis, N=32), primate-dispersed trees (Dialium spp., N=26), and in control plots located below other tree species (N= 4900 m²). Secondly, we considered all plots to compare the community of recruits in five sites characterized by contrasted levels of hunting and housing different seed disperser communities. Our preliminary results indicate (i) communities of recruits below hornbill-dispersed trees are significantly more dense and richer than in control plots, unlike these below primate-dispersed trees. Also, (ii) recruits in sites less affected by hunting, housing more large frugivores, including elephants, tend to belong to species with longer seeds. We conclude that hornbills generate recruitment foci under fruiting trees, which can serve as an efficient tool to monitor the ecological consequences of their extirpation. Moreover, we discuss the potential influence of the different studied frugivore taxa and the risk of their extirpation from afro-tropical forests on the composition of plant recruits’ community. [less ▲]

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See detailUsing a dynamic vegetation model for future projections of crop yields : application to Belgium in the framework of the VOTES and MASC projects
Jacquemin, Ingrid ULg; Henrot, Alexandra-Jane ULg; Fontaine, Corentin M. et al

Poster (2016, April 22)

Dynamic vegetation models (DVM) were initially designed to describe the dynamics of natural ecosystems as a function of climate and soil, to study the role of the vegetation in the carbon cycle. These ... [more ▼]

Dynamic vegetation models (DVM) were initially designed to describe the dynamics of natural ecosystems as a function of climate and soil, to study the role of the vegetation in the carbon cycle. These models are now directly coupled with climate models in order to evaluate feedbacks between vegetation and climate. But DVM characteristics allow numerous other applications, leading to amelioration of some of their modules (e.g., evaluating sensitivity of the hydrological module to land surface changes) and developments (e.g., coupling with other models like agent-based models), to be used in ecosystem management and land use planning studies. It is in this dynamic context about DVMs that we have adapted the CARAIB (CARbon Assimilation In the Biosphere) model. One of the main improvements is the implementation of a crop module, allowing the assessment of climate change impacts on crop yields. We try to validate this module at different scales: - from the plot level, with the use of eddy-covariance data from agricultural sites in the FLUXNET network, such as Lonzée (Belgium) or other Western European sites (Grignon, Dijkgraaf,. . . ), - to the country level, for which we compare the crop yield calculated by CARAIB to the crop yield statistics for Belgium and for different agricultural regions of the country. Another challenge for the CARAIB DVM was to deal with the landscape dynamics, which is not directly possible due to the lack of consideration of anthropogenic factors in the system. In the framework of the VOTES and the MASC projects, CARAIB is coupled with an agent-based model (ABM), representing the societal component of the system. This coupled module allows the use of climate and socio-economic scenarios, particularly interesting for studies which aim at ensuring a sustainable approach. This module has particularly been exploited in the VOTES project, where the objective was to provide a social, biophysical and economic assessment of the ecosystem services in four municipalities under urban pressure in the center of Belgium. The biophysical valuation was carried out with the coupled module, allowing a quantitative evaluation of key ecosystem services as a function of three climatic and socio-economic scenarios. [less ▲]

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See detailHigh-resolution climate and land surface interactions modeling over Belgium: current state and decennial scale projections
Jacquemin, Ingrid ULg; Henrot, Alexandra-Jane ULg; Beckers, Veronique et al

Poster (2016, April 21)

The interactions between land surface and climate are complex. Climate changes can affect ecosystem structure and functions, by altering photosynthesis and productivity or inducing thermal and hydric ... [more ▼]

The interactions between land surface and climate are complex. Climate changes can affect ecosystem structure and functions, by altering photosynthesis and productivity or inducing thermal and hydric stresses on plant species. These changes then impact socio-economic systems, through e.g., lower farming or forestry incomes. Ultimately, it can lead to permanent changes in land use structure, especially when associated with other non-climatic factors, such as urbanization pressure. These interactions and changes have feedbacks on the climate systems, in terms of changing: (1) surface properties (albedo, roughness, evapotranspiration, etc.) and (2) greenhouse gas emissions (mainly CO2, CH4, N2O). In the framework of the MASC project (« Modelling and Assessing Surface Change impacts on Belgian and Western European climate »), we aim at improving regional climate model projections at the decennial scale over Belgium and Western Europe by combining high-resolution models of climate, land surface dynamics and socio-economic processes. The land surface dynamics (LSD) module is composed of a dynamic vegetation model (CARAIB) calculating the productivity and growth of natural and managed vegetation, and an agent-based model (CRAFTY), determining the shifts in land use and land cover. This up-scaled LSD module is made consistent with the surface scheme of the regional climate model (RCM: ALARO) to allow simulations of the RCM with a fully dynamic land surface for the recent past and the period 2000-2030. In this contribution, we analyze the results of the first simulations performed with the CARAIB dynamic vegetation model over Belgium at a resolution of 1km. This analysis is performed at the species level, using a set of 17 species for natural vegetation (trees and grasses) and 10 crops, especially designed to represent the Belgian vegetation. The CARAIB model is forced with surface atmospheric variables derived from the monthly global CRU climatology or ALARO outputs (from a 4 km resolution simulation) for the recent past and the decennial projections. Evidently, these simulations lead to a first analysis of the impact of climate change on carbon stocks (e.g., biomass, soil carbon) and fluxes (e.g., gross and net primary productivities (GPP and NPP) and net ecosystem production (NEP)). The surface scheme is based on two land use/land cover databases, ECOPLAN for the Flemish region and, for the Walloon region, the COS-Wallonia database and the Belgian agricultural statistics for agricultural land. Land use and land cover are fixed through time (reference year: 2007) in these simulations, but a first attempt of coupling between CARAIB and CRAFTY will be made to establish dynamic land use change scenarios for the next decades. A simulation with variable land use would allow an analysis of land use change impacts not only on crop yields and the land carbon budget, but also on climate relevant parameters, such as surface albedo, roughness length and evapotranspiration towards a coupling with the RCM. [less ▲]

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See detailAssessing the Risk of Ecosystem Disruption in Europe using a Dynamic Vegetation Model driven by CMIP5 Regional Climatic Projections from EURO-CORDEX
Dury, Marie ULg; François, Louis ULg; Hambuckers, Alain ULg et al

Conference (2016, April 18)

While the combination of warmer and drier mean climatic conditions can have severe impacts on ecosystems, extreme events like droughts or heat waves that break the gradual climate change can have more ... [more ▼]

While the combination of warmer and drier mean climatic conditions can have severe impacts on ecosystems, extreme events like droughts or heat waves that break the gradual climate change can have more long-term consequences on ecosystem composition, functioning and carbon storage. Hence, it is essential to assess the changes in climate variability and the changes in frequency of extreme events projected for the future. Ecosystems could not be in a condition to adapt to these new conditions and might be disrupted. Here, the process-based dynamic vegetation model CARAIB DVM was used to evaluate and analyze how future climate and extreme events will affect European ecosystems. To quantify the uncertainties in the climatic projections and in their potential impacts on ecosystems, the vegetation model was driven with the outputs of different regional climatic models (RCMs), nested in CMIP5 GCM projections for the EURO-CORDEX project: ALADIN53 (Météo-France/CNRM), RACMO22E (KNMI), RCA4 (SMHI) and REMO2009 (MPI-CSC) RCMs. These climatic projections are at a high spatial resolution (0.11-degree, ≈ 12 km). CARAIB simulations were performed across Europe over the historical period 1951-2005 and the future period 2006-2100 under RCP4.5 and RCP8.5 emission scenarios. We simulated a set of 99 individual species (47 herbs, 12 shrubs and 40 trees) representing the major European ecosystem flora. First, we analyzed the climatic variability simulated by the climatic models over the historical period and compared it with the observed climatic variability. None of these climatic models can reproduce accurately the present natural climatic variability. Then, to assess the risk of ecosystem disruption in the future and to identify the vulnerable areas in Europe, we created an index combining several CARAIB outputs: runoff, mean NPP, soil turnover, burned area, appearance and disappearance of species. We evaluated the severity of change projected for these variables (period 2070-2099) relative to their current variability (period 1970-1999). Mean changes were considered severe if they exceed observed variability. The highest values of the index were found in southern Europe, indicating that the amplitude of the expected ecosystem changes largely exceeds current interannual variability in this area. This spatial risk index and the projections of potential shifts in species distributions are directly dedicated to current forest management to guide in planting or in assisted migration. [less ▲]

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See detailStructure and floristic composition of Kibira rainforest, Burundi
Hakizimana, Dismas; Huynen, Marie-Claude ULg; Hambuckers, Alain ULg

in Tropical Ecology (2016), 57(4), 739-749

This paper gives the results of the first census of trees in the 32.15 ha plot in order to provide tree species richness in Kibira rainforest (Burundi). All trees ≥ 10 cm dbh were permanently tagged and ... [more ▼]

This paper gives the results of the first census of trees in the 32.15 ha plot in order to provide tree species richness in Kibira rainforest (Burundi). All trees ≥ 10 cm dbh were permanently tagged and their girth measured. The forest structure pattern analysed were diameter at breast height (dbh), basal area, relative dominance, and relative density, Importance Value Index (IVI) and Family Importance Value (FIV). In total, 6504 trees representing 70 species, 67 genera and 37 families were recorded. Tree density was 202 stems/ha, with a basal area of 21.05m²/ha. Seventeen families were represented by a single species each, eleven families were represented by two species each, five families were represented by three species each, and four families were represented by four species each. The most important families in relation to FIV were Euphorbiaceae, Myrtaceae and Araliaceae. Macaranga kilimandscharica, Syzygium guineense and Polyscias fulva were the most important species in relation to IVI. Two tree species were found to be endemic to the Albertine Rift and one species probably endemic to the Albertine Rift. The Shannon-Weiner index (H') and eveness index (J') were respectively 3.18 and 0.75. This study provides a baseline for the management of Kibira National Park. As local communities still depend on forest resources, conservation awareness-raising and education actions have to focus in nearby villages, and growing some fast-growing native trees in the vicinity of the settlement, would be helpful for local communities, this would reduce their dependence on forest resources. [less ▲]

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See detailEcosystem services provided by a large endangered primate in a forest-savanna mosaic landscape
Trolliet, Franck ULg; Serckx, Adeline ULg; Forget, Pierre-Michel et al

in Biological Conservation (2016)

Forested landscapes are increasingly affected by human activities, but little is known about the role of large endangered frugivores as seed dispersers in such ecosystems. We investigated the role played ... [more ▼]

Forested landscapes are increasingly affected by human activities, but little is known about the role of large endangered frugivores as seed dispersers in such ecosystems. We investigated the role played by the bonobo (Pan paniscus) in a human-altered forest-savannamosaic in Democratic Republic of the Congo. The studied groups are part of a community-based conservation programme but live at the interface with human activities. We identified dispersed species via faecal analysis, classified them into a regeneration guild and a seed size category, determined the effect of gut transit on seed germination, and the habitat use of bonobos. Bonobos dispersed intact seeds of 77 species, 80.8% of which were large-seeded (≥10mmlong), ofwhich fewcan be dispersed by sympatric frugivores. They dispersed a majority (49%) of shade-bearers that thrive in forest understory with limited amount of light, all of whichwere large-seeded. Transit had an overall positive effect on seed germination. Bonobos used various habitat types, showing preferences for understorywith intermediate light availability and dominated by woody or herbaceous vegetation. This dispersal pattern probably enhances recruitment of shadebearers, and we thus hypothesized that those species benefited from directed dispersal by bonobos. This threatened frugivore provides unique dispersal services and likely plays a paramount functional role in the regeneration of late successional forests in this mosaic landscape. Management plans should pay particular attention to the role of large and rare frugivores in human-dominated regions as their disappearance could disrupt forest succession to a climax state. [less ▲]

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See detailAssessing the Risk of Ecosystem Disruption in Europe using a Dynamic Vegetation Model driven by CMIP5 Regional Climatic Projections from EURO-CORDEX
Dury, Marie ULg; Hambuckers, Alain ULg; Henrot, Alexandra-Jane ULg et al

Conference (2015, December 18)

While the combination of warmer and drier mean climatic conditions can have severe impacts on ecosystems, extreme events like droughts or heat waves that break the gradual climate change can have more ... [more ▼]

While the combination of warmer and drier mean climatic conditions can have severe impacts on ecosystems, extreme events like droughts or heat waves that break the gradual climate change can have more long-term consequences on ecosystem composition, functioning and carbon storage. Hence, it is essential to assess the changes in climatic variability and the changes in frequency of extreme events projected for the future. Ecosystems could not be in a condition to adapt to these new conditions and might be disrupted. Here, the process-based dynamic vegetation model CARAIB DVM was used to evaluate and analyze how future climate and extreme events will affect European ecosystems. To quantify the uncertainties in the climatic projections and in their potential impacts on ecosystems, the vegetation model was driven with the outputs of different regional climatic models (RCMs), nested in CMIP5 GCM projections for the EURO-CORDEX project. We used the ALADIN version 5.3 (Météo-France/CNRM) and other EURO-CORDEX RCMs. These climatic projections are at a high spatial resolution (0.11-degree, ~12 km). CARAIB simulations were performed across Europe over the historical period 1951-2005 and the future period 2006-2100 under RCP4.5 and RCP8.5 emission scenarios. We simulated a set of 99 individual species (47 herbs, 12 shrubs and 40 trees) representing the major European ecosystem flora. First, we analyzed the climatic variability simulated by the climatic models over the historical period and compared it with the observed climatic variability. None of these climatic models can reproduce accurately the present natural climatic variability. Then, to assess the risk of ecosystem disruption in the future and to identify the vulnerable areas in Europe, we created an index combining several CARAIB outputs: runoff, mean NPP, soil turnover, burned area, appearance and disappearance of species. We evaluated the severity of change projected for these variables (period 2071-2100) relative to their current variability (period 1961-1990). Mean changes were considered severe if they exceed observed variability. The highest values of the index were found in southern Europe, indicating that the amplitude of the expected ecosystem changes largely exceeds current interannual variability in this area. [less ▲]

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See detailEffect of hunting pressure and forest fragmentation on seed dispersal of Staudtia kamerunensis (Myristicaceae) in the Western Congolian forest-savanna mosaic
Trolliet, Franck ULg; Forget, Pierre-Michel; Huynen, Marie-Claude ULg et al

Conference (2015, June 22)

Numerous studies have investigated the impact of hunting and forest fragmentation on seed dispersal processes, but few of them in Africa. The African continent, however, holds the greatest abundance of ... [more ▼]

Numerous studies have investigated the impact of hunting and forest fragmentation on seed dispersal processes, but few of them in Africa. The African continent, however, holds the greatest abundance of large frugivores on Earth and is subject to increasing levels of hunting and forest fragmentation. Frugivory and seed dispersal in the pan-tropical family Myristicaceae has been well studied in the Neotropics, but remain barely known in Afro-tropical forests. Here we investigated how hunting, forest cover, and fruit availability influence the dispersal capacities of Staudtia kamerunensis in a mosaic composed of forest patches and savannas in D.R. Congo. We selected 34 fertile female S. kamerunensis trees distributed, at a landscape scale (300 km²), across 5 sites characterized by a gradient of hunting pressures and density of the study trees. The trees varied in size and surrounding forest cover (patch and corridors). We quantified the percentages of seed dispersal failure using litter trap and fruit remains during the entire 2013 fruiting season, and identified fruit eaters through focal observations. The most frequently observed frugivore was the White-thighed Hornbill (Bycanistes albotibialis). Our GLMM analyses show that increasing hunting pressure, decreasing abundance of B. albotibialis and decreasing forest cover near focal trees significantly increased dispersal failure. The limited forest cover of some patches, resulting from the highly fragmented feature of the landscape, and hunting pressure, are likely to impact negatively the abundance of B. albotibialis. Consequently, we suggest the dispersal system reached saturation because of a lack of effective seed dispersal away from parent trees. [less ▲]

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See detailModelling carbon fluxes of forest and grassland ecosystems in Western Europe using the CARAIB dynamic vegetation model: evaluation against eddy covariance data.
Henrot, Alexandra-Jane ULg; François, Louis ULg; Dury, Marie ULg et al

Poster (2015, April)

Eddy covariance measurements are an essential resource to understand how ecosystem carbon fluxes react in response to climate change, and to help to evaluate and validate the performance of land surface ... [more ▼]

Eddy covariance measurements are an essential resource to understand how ecosystem carbon fluxes react in response to climate change, and to help to evaluate and validate the performance of land surface and vegetation models at regional and global scale. In the framework of the MASC project (« Modelling and Assessing Surface Change impacts on Belgian and Western European climate »), vegetation dynamics and carbon fluxes of forest and grassland ecosystems simulated by the CARAIB dynamic vegetation model (Dury et al., iForest - Biogeosciences and Forestry, 4:82-99, 2011) are evaluated and validated by comparison of the model predictions with eddy covariance data. Here carbon fluxes (e.g. net ecosystem exchange (NEE), gross primary productivity (GPP), and ecosystem respiration (RECO)) and evapotranspiration (ET) simulated with the CARAIB model are compared with the fluxes measured at several eddy covariance flux tower sites in Belgium and Western Europe, chosen from the FLUXNET global network (http://fluxnet.ornl.gov/). CARAIB is forced either with surface atmospheric variables derived from the global CRU climatology, or with in situ meteorological data. Several tree (e.g. Pinus sylvestris, Fagus sylvatica, Picea abies) and grass species (e.g. Poaceae, Asteraceae) are simulated, depending on the species encountered on the studied sites. The aim of our work is to assess the model ability to reproduce the daily, seasonal and interannual variablility of carbon fluxes and the carbon dynamics of forest and grassland ecosystems in Belgium and Western Europe. [less ▲]

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See detailLa menace climatique sur les plantes
Hambuckers, Alain ULg

Conference given outside the academic context (2015)

L’exposé commence par un bref rappel du contexte climatique (évolution de la température globale au cours des 150 dernières années, grandes tendances des changements climatiques prévus par les modèles ... [more ▼]

L’exposé commence par un bref rappel du contexte climatique (évolution de la température globale au cours des 150 dernières années, grandes tendances des changements climatiques prévus par les modèles globaux). Je présente ensuite quelques exemples d’observations de modification de la végétation au cours des décennies passées (enrichissement en espèces de sommets alpins, augmentation de la mortalité de la végétation ligneuse en région sahélienne, variation de la limite altitudinale de présence d’espèces endémiques sur l’île de Ténérife) et les limites de leur interprétation (prise en compte des modifications de l’occupation du sol, de la pollution atmosphérique, des interactions biotiques). On s’intéresse ensuite à la prédiction des changements dans le futur qui nécessite de comprendre les réponses physiologiques des plantes aux facteurs suivants : l’augmentation de la température, les variations du régime de précipitation, les effets des épisodes climatiques extrêmes (canicules, sécheresses), l’augmentation de la concentration en CO2, l’évolution des conditions biotiques. Armé de ces informations, on peut alors examiner des méthodes d’inférences comme l’analyse des distributions présentes, les modèles de niches, ou les modèles dynamiques de végétation et quelques résultats produits par ces méthodes. Pour les espèces tropicales nos résultats donnent plutôt à penser que les aires de distributions s’étendront dans le futur, avec une très large conservation de l’aire originale. Ces résultats sont finalement mis en perspective avec d’autres facteurs d’altération de l’environnement, et en particulier la destruction des habitats. Ceci nous permet de constater que le principal problème contre lequel il faut continuer à agir, en priorité, reste la destruction des habitats naturels et semi-naturels, y compris en Belgique. [less ▲]

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See detailModelling the distribution of key tree species used by lion tamarins in the Brazilian Atlantic forest under a scenario of future climate change
Raghunathan, Poornima ULg; François, Louis ULg; Huynen, Marie-Claude ULg et al

in Regional Environmental Change (2015), 15

We used three IPCC climate change scenarios (A1B, A2 and B1) in a dynamic vegetation model (CARAIB), to determine the potential future distribution of 75 tree species used by two endemic primate species ... [more ▼]

We used three IPCC climate change scenarios (A1B, A2 and B1) in a dynamic vegetation model (CARAIB), to determine the potential future distribution of 75 tree species used by two endemic primate species from the Brazilian Atlantic Forest (BAF). Habitat conservation is a vital part of strategies to protect endangered species, and this is a new approach to understanding how key plant species needed for survival of golden lion tamarins (Leontopithecus rosalia) and golden-headed lion tamarins (L. chrysomelas) might be affected by climate change and what changes to their distribution are likely. The model accurately predicted the current distribution of BAF vegetation types, for 66 % of the individual tree species with 70 % agreement obtained for presence. In the simulation experiments for the future, 72 out of 75 tree species maintained more than 95 % of their original distribution and all species showed a range expansion. At the biome level, we note a substantial decrease in the sub-tropical forest area. There is some fragmentation of the savannah, which is encroached mostly by tropical seasonal forest. Where the current distribution shows a large sub-tropical forest biome, it has been replaced or encroached by tropical rainforest. The results suggested that the trees may benefit from an increase in temperature, if and only if soil water availability is not altered significantly, as was the case with climate simulations that were used. However, these results must be coupled with other information to maximise usefulness to conservation since BAF is already highly fragmented and subject to high anthropic pressure. © 2014 Springer-Verlag Berlin Heidelberg. [less ▲]

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See detailCharacterization of Nest Sites of Chimpanzees (Pan troglodytes schweinfurthii) in Kibira National Park, Burundi
Hakizimana, Dismas; Hambuckers, Alain ULg; Brotcorne, Fany ULg et al

in African Primates (2015), 10

Abstract: Kibira National Park is the only site in Burundi that harbors a large number of chimpanzees (Pan troglodytes schweinfurthii). While information on factors influencing the selection of nest sites ... [more ▼]

Abstract: Kibira National Park is the only site in Burundi that harbors a large number of chimpanzees (Pan troglodytes schweinfurthii). While information on factors influencing the selection of nest sites by chimpanzees is available for other locations of the species’ range, this information is lacking for Kibira National Park. This is mainly due to the political troubles that prevailed in the country from 1993 until 2007, making study there difficult. To better protect this chimpanzee population, it is crucial to survey nest sites to identify the tree species, physical characteristics of the trees and habitat type that chimpanzees preferentially use for nesting. Therefore, in this study, we investigated: 1) the tree species used by chimpanzees for building their nests; 2) nest tree availability in the study area; 3) whether chimpanzee selection of a nest tree is based on physical characteristics such as diameter at breast height, lowest branch height, tree size and crown height; and 4) whether chimpanzees choose their nest sites according to topography and canopy types. We collected data monthly along 16 transects of 3 km each, from September 2011 to February 2013 (18 months). However, data related to the measurements of nests and nest trees were collected for only the last 12 months, from March 2012 to February 2013. We identified tree species used for nesting, and measured physical characteristics of trees used as opposed to surrounding trees unused. The results showed that chimpanzees select certain tree species to build their nests. Among the 32 species of trees bearing nests, chimpanzees used 12 species significantly more frequently than expected and 11 species significantly less frequently than expected. In addition, trees bearing nests were significantly larger and taller than the surrounding trees and had higher lowest branch and bigger canopies. [less ▲]

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See detailThe seed dispersal of the afro- tropical tree species Staudtia kamerunensis (Myristicaceae)
Hambuckers, Alain ULg

Scientific conference (2014, December 27)

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