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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 ULiege; Zuniga, Lilian; Dury, Marie ULiege 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 detailDeforestation drives functional diversity and fruit quality changes in a tropical tree assemblage
Pessoa, Michaele S.; Hambuckers, Alain ULiege; Benchimol, Maíra et al

in Perspectives in Plant Ecology, Evolution & Systematics (2017), 28(C), 78-86

Functional traits associated with plant-animal interactions are essential for forest functionality, given that a higher diversity of fruit traits is likely to maintain a more diverse assemblage of ... [more ▼]

Functional traits associated with plant-animal interactions are essential for forest functionality, given that a higher diversity of fruit traits is likely to maintain a more diverse assemblage of frugivores and consequently promote the seed dispersal function. Yet, shade-intolerant species tend to persist in human-modified landscapes in the long term, which in turn is expect to reduce fruit trait diversity. Here we evaluate how forest cover at the landscape-scale influences the functional diversity of fruit traits, considering the zoochoric tree community and two regeneration strategies separately (shade-tolerant and shade-intolerant species). We sampled 20 forest remnants in the Brazilian Atlantic Forest, located in landscapes with forest cover ranging from 2 to 93%. In each remnant, we established five plots of 25 ×4 m and marked all trees≥5 cm diameter at breast height (DBH). We compared morphological and chemical attributes of fleshy fruits directly related to the attraction of frugivores, and evaluated the similarity of the zoochoric tree assemblage composition along the forest cover gradient, taking into account the two regeneration strategies. We calculated four functional indices (richness, evenness, divergence, and community-level weighted means of trait values) and used either linear models or spatial mixed linear models to evaluate the effects of forest cover on functional diversity. Our main results revealed that forest cover loss has negatively affected fruit functional diversity for the overall zoochoric community. Forest cover loss also affected functional richness and functional evenness for total and shade-tolerant species, and was positively correlated with the content of protein and lipid in fruits of shade-intolerant species. Additionally, sites exhibiting a lower amount of forest cover showed greater compositional similarity among shade-intolerant species but reduced similarity among shade-tolerant species. We conclude that patterns of species reassembly triggered by landscape-scale deforestation decreases the capacity of the remaining forest for provisioning food resources for frugivore assemblages. The maintenance of shade-tolerant species is pivotal in deforested areas, since their fruit quality is not offset by shade-intolerant species. This is particularly important, mainly because shade-intolerant species are those still persisting in disturbed forests; however, their presence will not provide the same food quality supplied by those species lost. [less ▲]

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See detailMicrorefugia, climate change, and conservation of Cedrus atlantica in the Rif Mountains, Morocco
Cheddadi, Rachid; Henrot, Alexandra-Jane ULiege; François, Louis ULiege et al

in Frontiers in Ecology and Evolution (2017), 5

This study reconstructs and interprets the changing range of Atlas cedar in northern Morocco over the last 9,000 years. A synthesis of fossil pollen records indicated that Atlas cedars occupied a wider ... [more ▼]

This study reconstructs and interprets the changing range of Atlas cedar in northern Morocco over the last 9,000 years. A synthesis of fossil pollen records indicated that Atlas cedars occupied a wider range at lower elevations during the mid-Holocene than today. The mid-Holocene geographical expansion reflected low winter temperatures and higher water availability over the whole range of the Rif Mountains relative to modern conditions. A trend of increasing aridity observed after 6,000 years BP progressively reduced the range of Atlas cedar and prompted its migration toward elevations above 1,400 masl. To assess the impact of climate change on cedar populations over the last decades, we performed a transient model simulation for the period between 1960 and 2010. Our simulation showed that the range of Atlas cedar decreased by about 75% over the last 50 years and that the eastern populations of the range in the Rif Mountains were even more threatened by the overall lack of water availability than the western ones. Today, Atlas cedar populations in the Rif Mountains are persisting in restricted and isolated areas (Jbel Kelti, Talassemtane, Jbel Tiziren, Oursane, Tidighine) that we consider to be modern microrefugia. Conservation of these isolated populations is essential for the future survival of the species, preserving polymorphisms and the potential for population recovery under different climatic conditions. [less ▲]

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See detailFrugivorous birds influence the spatial organization of tropical forests through the generation of seedling recruitment foci under zoochoric trees
Trolliet, Franck ULiege; Forget, Pierre-Michel; Doucet, Jean-Louis ULiege et al

in Acta Oecologica: International Journal of Ecology (2017), 85

Animal-mediated seed dispersal is recognized to influence the spatial organization of plant communities but little is known about how frugivores cause such patterns. Here, we explored the role of ... [more ▼]

Animal-mediated seed dispersal is recognized to influence the spatial organization of plant communities but little is known about how frugivores cause such patterns. Here, we explored the role of hornbills and primates in generating recruitment foci under two zoochoric trees, namely Staudtia kamerunensis (Myristicaceae) and Dialium spp. (Fabaceae - Caesalpiniodea) in a forest-savanna mosaic landscape in D.R. Congo. We also examined the influence of the availability of fruits in the neighborhood and the amount of forest cover in the landscape on such clumping patterns. The density and species richness of hornbill-dispersed and the density of primate-dispersed seedlings were significantly higher under Staudtia kamerunensis trees than at control locations. However, we did not find such patterns under Dialium spp. trees compared to control locations except for the density of hornbill-dispersed seedlings which was lower at control locations. Also, we found that an increasing amount of forest cover in the landscape was associated with an increase in the density of hornbill-dispersed seedlings, although the tendency was weak (R2 = 0.065). We concluded that S. kamerunensis acts as a recruitment foci and plays a structuring role in Afrotropical forests. Hornbills were probably the main frugivore taxon responsible for the clumping under that tree and appear as a key ecological component in fragmented and disturbed landscapes where the diversity of large frugivores such as primates is reduced. Our findings improve our understanding of the causal mechanisms responsible for the spatial organization of tropical forests. [less ▲]

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See detailHow can seed removal rates of zoochoric tree species be assessed quickly and accurately?
Hambuckers, julien ULiege; Dauvrin, Alice; Trolliet, Franck ULiege et al

in Forest Ecology and Management (2017), 403

The quantification of seed dispersal and predation processes has been gaining increased importance in the assessment of forest responses to anthropogenic disturbance, but also in developing an ... [more ▼]

The quantification of seed dispersal and predation processes has been gaining increased importance in the assessment of forest responses to anthropogenic disturbance, but also in developing an understanding of forest dynamics facing particular reproductive strategies. Seed removal rate is a reliable estimator of animal activities relating to these processes and can be quickly and easily estimated using a rapid assessment method (RAM) described by Lermyte & Forget (2009) and Boissier et al. (2014). This method consists in selecting trees reaching a given fruit crop in plots of interest and estimating, under each tree, the proportion of removed seeds in a single quadrat among the places having the highest crops; the proportion of removed seeds is obtained by enumeration of fruit scraps and intact fruits and estimation of their seed contents. The objective of this work is to evaluate the reliability of this method and to propose alternative estimation protocols (APs) in order to obtain an index of animal interaction with seeds. To do so, we estimated produced and removed seed numbers in up to 30 random 1 sq.m. quadrats under a total of 19 trees of Afzelia bipindensis, Dialium pachyphyllum/zenkeri and Xylopia staudtii. Secondly, we investigated the influence of tree size and fruit production on seed removal rate using a generalized linear mixed model. Thirdly, we used a generalized linear mixed model and a bootstrap procedure to test if RAM and APs are biased. Then, we compared their accuracy throughout their mean squared error, also obtained with a bootstrap approach. Despite its interesting accuracy, we showed that the RAM is positively biased. Removal rate was obviously influenced by canopy size and fruit production whereas the quadrats with higher fruit production have higher seed removal rates. Thus, trees with representative sizes and crops of the studied plots have to be sampled. Secondly, as an AP, random selection of several quadrats was found to be the best method. Based on these results, we recommend using the mean of three random quadrats per tree to estimate seed removal rate. It is an unbiased estimator, more accurate and more time efficient than the RAM. However, attention should be paid to select a proper quadrat size, in line with seed and fruit numbers, since the accuracy of the methods depends on these quantities. Such a choice could be made using a mean squared error criterion obtained from a preliminary intensive sampling of some specimens of the focal species. [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 ULiege; Dury, Marie ULiege; Henrot, Alexandra-Jane ULiege 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 ULiege; Hambuckers, Alain ULiege; Henrot, Alexandra-Jane ULiege 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 ULiege; Forget, Pierre-Michel; Doucet, Jean-Louis ULiege 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 ULiege; Henrot, Alexandra-Jane ULiege; 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 ULiege; Henrot, Alexandra-Jane ULiege; 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 ULiege; François, Louis ULiege; Hambuckers, Alain ULiege 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 ULiege; Hambuckers, Alain ULiege

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 ULiege; Serckx, Adeline ULiege; 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 ULiege; Hambuckers, Alain ULiege; Henrot, Alexandra-Jane ULiege 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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Peer Reviewed
See detailEffect of hunting pressure and forest fragmentation on seed dispersal of Staudtia kamerunensis (Myristicaceae) in the Western Congolian forest-savanna mosaic
Trolliet, Franck ULiege; Forget, Pierre-Michel; Huynen, Marie-Claude ULiege 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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Full Text
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 ULiege; François, Louis ULiege; Dury, Marie ULiege 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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Full Text
See detailLa menace climatique sur les plantes
Hambuckers, Alain ULiege

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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