Publications of Marie Dury
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See detailRefining the outputs of a dynamic vegetation model (CARAIB):Research at ULiège, Belgium
Hambuckers, Alain ULiege; Paillet, Marc ULiege; Henrot, Alexandra-Jane ULiege et al

Scientific conference (2019, March 19)

Dynamic vegetation models (DVMs) are process-based models combining the inputs and the outputs of sub-models, possibly in feedback loops, to simulate the plant functions. The sub-models compute conditions ... [more ▼]

Dynamic vegetation models (DVMs) are process-based models combining the inputs and the outputs of sub-models, possibly in feedback loops, to simulate the plant functions. The sub-models compute conditions outside and inside the plant and physiological reactions from the environmental data (climate, light intensity, air CO2 concentration, soil properties). DVMs are tools of choice to predict the future and the past of the vegetation taking into account climatic variations. The emergence of new questions in the context of climate change, particularly on threatened species or on commercial species, compels to apply DVMs to species while the information to parameterize and validate them is largely lacking. Of particular importance are the morpho-physiological traits. These were intensively studied within the hypothesis that they could be used to predict plant performances. This hypothesis finally revealed not very suitable, but it brought to light that important traits controlling photosynthesis and water relationships could strongly vary within each species in response to environmental conditions. We studied the Atlas cedar (Cedrus atlantica (Endl.) Manetti ex Carrière), in Morocco (northern Africa). It is a threatened tree species of important economic value. We also studied the English oak (Quercus robur L.) and the sessile oak (Quercus petraea (Matt.) Liebl.) in eastern Belgium. In a series of localities, we determined several traits (specific leaf area, leaf C/N, sapwood C/N, as well as for the cedar, leaf longevity) and we assessed biomass and net primary productivity as validation data, thanks to forest inventories, dendrochronology analyses and allometric equations combined with leaf area index estimations. We compared the model simulations of the CARAIB DVM when varying the set of traits (direct site estimates or default values) to the field estimates of biomass and net primary productivity. We found that trait default values provide sufficient information for the DVM to compute mean output values but low ability to reproduce between site variations. On the contrary, the in situ traits improve drastically this ability, which indicates that the plant performances are the results of acclimation to the evolving local environmental conditions. [less ▲]

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See detailRefining the outputs of a dynamic vegetation model (CARAIB): the importance of plant traits to improve prediction accuracy at tree species level
Hambuckers, Alain ULiege; Paillet, Marc ULiege; Henrot, Alexandra-Jane ULiege et al

Conference (2019, March 11)

Dynamic vegetation models (DVMs) are process-based models combining the inputs and the outputs of sub-models, possibly in feedback loops, to simulate the plant functions. The sub-models compute conditions ... [more ▼]

Dynamic vegetation models (DVMs) are process-based models combining the inputs and the outputs of sub-models, possibly in feedback loops, to simulate the plant functions. The sub-models compute conditions outside and inside the plant and physiological reactions from the environmental data (climate, light intensity, air CO2 concentration, soil properties). DVMs are tools of choice to predict the future and the past of the vegetation taking into account climatic variations. The emergence of new questions in the context of climate change, particularly on threatened species or on commercial species, compels to apply DVMs to species while the information to parameterize and validate them is largely lacking. Of particular importance are the morpho-physiological traits. These were intensively studied within the hypothesis that they could be used to predict plant performances. This hypothesis finally revealed not very suitable, but it brought to light that important traits controlling photosynthesis and water relationships could strongly vary within each species in response to environmental conditions. We studied the Atlas cedar (Cedrus atlantica (Endl.) Manetti ex Carrière), in Morocco (northern Africa). It is a threatened tree species of important economic value. We also studied the English oak (Quercus robur L.) and the sessile oak (Quercus petraea (Matt.) Liebl.) in eastern Belgium. In a series of localities, we determined several traits (specific leaf area, leaf C/N, sapwood C/N, as well as for the cedar, leaf longevity) and we assessed biomass and net primary productivity as validation data, thanks to forest inventories, dendrochronology analyses and allometric equations combined with leaf area index estimations. We compared the model simulations of the CARAIB DVM when varying the set of traits (direct site estimates or default values) to the field estimates of biomass and net primary productivity. We found that trait default values provide sufficient information for the DVM to compute mean output values but low ability to reproduce between site variations. On the contrary, the in situ traits improve drastically this ability, which indicates that the plant performances are the results of acclimation to the evolving local environmental conditions. [less ▲]

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See detailContrasting climate risks predicted by dynamic vegetation and ecological niche-based models applied to tree species in the Brazilian Atlantic Forest
Raghunathan, Poornima ULiege; François, Louis ULiege; Dury, Marie ULiege et al

in Regional Environmental Change (2019), 19

Climate change is a threat to natural ecosystems. To evaluate this threat and, where possible, respond, it is useful to understand the potential impacts climate change could have on species’ distributions ... [more ▼]

Climate change is a threat to natural ecosystems. To evaluate this threat and, where possible, respond, it is useful to understand the potential impacts climate change could have on species’ distributions, phenology, and productivity. Here, we compare future scenario outcomes between a dynamic vegetation model (DVM; CARbon Assimilation In the Biosphere (CARAIB)) and an ecological niche-based model (ENM; maximum entropy model) to outline the risks to tree species in the Brazilian Atlantic Forest, comprising the habitats of several endemic species, including the endangered primate Leontopithecus chrysomelas (golden-headed lion tamarin; GHLT), our species of interest. Compared to MaxENT, theDVMpredicts larger present-day species ranges. Conversely, MaxENT ranges are closer to sampled distributions of the realised niches. MaxENT results for two future scenarios in four general circulation models suggest that up to 75% of the species risk losing more than half of their original distribution. CARAIB simulations are more optimistic in scenarios with and without accounting for potential plant-physiological effects of increased CO2, with less than 10% of the species losing more than 50% of their range. Potential gains in distribution outside the original area do not necessarily diminish risks to species, as the potential new zones may not be easy to colonise. It will also depend on the tree species’ dispersal ability. So far, within the current range of L. chrysomelas, CARAIB continues to predict persistence of most resource trees, while MaxENT predicts the loss of up to 19 species out of the 59 simulated. This research highlights the importance of choosing the appropriate modelling approach and interpretation of results to understand key processes. [less ▲]

Detailed reference viewed: 61 (9 ULiège)
See detailISIMIP2a Simulation Data from Biomes Sector (V. 1.1)
Reyer, Christopher; Asrar, Gassem; Betts, Richard et al

Textual, factual or bibliographical database (2019)

This database collects the results from the ISIMIP2a simulation experiments carried out with from 8 global vegetation models (CARAIB, DLEM, JULES-B1, LPJ-GUESS, LPJmL, ORCHIDEE, VEGAS, VISIT) according to ... [more ▼]

This database collects the results from the ISIMIP2a simulation experiments carried out with from 8 global vegetation models (CARAIB, DLEM, JULES-B1, LPJ-GUESS, LPJmL, ORCHIDEE, VEGAS, VISIT) according to the ISIMIP2a protocol (https://www.isimip.org/protocol/#isimip2a). [less ▲]

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See detailAre the climatic ranges of plant species impacted by atmospheric CO2 ? An attempt of quantification with a dynamic vegetation model
François, Louis ULiege; Henrot, Alexandra-Jane ULiege; Dury, Marie ULiege et al

Conference (2018, August 16)

The observed present-day climatic ranges of plant species are frequently used by palaeobotanists and palynologists to reconstruct the climate evolution in the past. This is, for instance, the case of the ... [more ▼]

The observed present-day climatic ranges of plant species are frequently used by palaeobotanists and palynologists to reconstruct the climate evolution in the past. This is, for instance, the case of the widely used “Coexistence Approach” method, which has provided a wealth of palaeoclimatic data on many periods of the Neogene. Such vegetation-based palaeoclimate reconstruction methods rest on the uniformitarian assumption that the climatic tolerances of plant species, or the way their establishment and growth respond to climate parameters, have not changed markedly over time. This hypothesis can be questioned, because climatic tolerances and growth of plant species may depend on many factors likely to change over time. A first example is that other abiotic and biotic factors allowing the plant presence have probably changed in the course of time. Another example is genetic evolution that may affect climate resistance and end up to some adaptation of the populations as climate is changing. Atmospheric CO2 may also modify the plant response. It is not accounted for in the vegetation-based palaeoclimatic reconstruction methods, but may alter the tolerance of plant species to aridity through stomatal closure or stomatal density changes. Moreover, a rise of atmospheric CO2 stimulates photosynthesis through the well-known CO2 fertilisation effect. How far this effect impacts plant growth and how long it can persist is still much debated in the scientific community. It likely depends on the nutrient abundance in the soils. However, if CO2 stimulates growth, it will also facilitate the colonisation of extreme environments by plant species. Indeed, their growth rate between two successive extreme climatic events will be enhanced and, so, the accumulated biomass will be larger and the likelihood to find their signature in the palaeovegetation records will increase. In this contribution, we attempt to quantify this impact of CO2 on the climatic ranges of plant species by using the CARAIB dynamic vegetation model. This dynamic vegetation model can be run at the species level. We use a set of tree species from various climatic zones over different continents, for which the model has proved a good ability to simulate the present-day distribution. The model is run for different levels of atmospheric CO2, but with exactly the same climatic inputs. The simulated tree species distributions versus different climate variables (mean annual temperature, coldest month temperature, mean annual precipitation, precipitation of the driest month, etc) are then analysed and compared among the different CO2 configurations. [less ▲]

Detailed reference viewed: 93 (8 ULiège)
See detailSimulating last glacial and postglacial distributions of African tropical trees with a dynamic vegetation model.
Dury, Marie ULiege; Henrot, Alexandra-Jane ULiege; Lézine, Anne-Marie et al

Conference (2018, August 16)

Climate change and human pressure threaten species richness of African tropical forests. Understanding how the past climate changes have shaped the current distribution and composition of African ... [more ▼]

Climate change and human pressure threaten species richness of African tropical forests. Understanding how the past climate changes have shaped the current distribution and composition of African rainforests can certainly help to the ecosystem conservation in the future. This topic is addressed in the framework of the multi-disciplinary AFRIFORD project (Genetic and palaeoecological signatures of African rainforest dynamics: pre-adapted to change?, http://www.ulb.ac.be/facs/sciences/afriford/). In parallel to genetic and palynological analyses, the CARAIB dynamic vegetation model is applied at the level of African tropical plant species to simulate change in their distributions from the Last Glacial Maximum (21,000 years BP) to the present in sub-Saharan Africa. We prepared a set of about a hundred species, mostly composed of tropical tree species (evergreen/deciduous, cool/warm taxa) for which we compiled observed occurrence data (e.g.., RAINBIO database), determined climatic requirements and gathered some specific traits (e.g., TRY database). From LGM to present time, the vegetation model is forced with the 1-kyr snapshot outputs of the HadCM3 climate model. Statistically downscaled at a spatial resolution of 0.5°, we only kept modelled past anomalies that we added to the GSWP3 (20 CR) climate data chosen as the reference for the historical period. Sub-Saharan simulations are performed with CARAIB forced by these climatic projections to simulate the net primary productivity of the species over time and space. We analyse the modelled changes in tropical forest composition and extension as well as in the distribution of individual species whose glacial refugia and postglacial dynamics remain poorly known. [less ▲]

Detailed reference viewed: 85 (9 ULiège)
See detailSimulating seed dispersal to reproduce past dynamics and distribution of African tropical trees.
Dury, Marie ULiege; Hardy, Olivier; Migliore, Jérémy et al

Poster (2018, March 28)

Climate change and human pressure threaten species richness of African tropical forests. Understanding how the past climate changes have shaped the current distribution and composition of African ... [more ▼]

Climate change and human pressure threaten species richness of African tropical forests. Understanding how the past climate changes have shaped the current distribution and composition of African rainforests can certainly help to the ecosystem conservation in the future. In the framework of the multi-disciplinary AFRIFORD project (Genetic and palaeoecological signatures of African rainforest dynamics: pre-adapted to change?, http://www.ulb.ac.be/facs/sciences/afriford/), this kind of questions is addressed. The CARAIB dynamic vegetation model is applied at the level of representative African tropical tree species to reconstruct their past and present distributions in equatorial Africa. To reproduce fully population dynamics, the results of the vegetation model are combined with a seed dispersal model. At first, we simulate with the CARAIB DVM the changes over time in the potential distribution of the tree species studied in AFRIFORD taking competition between species into account. From Last Glacial Maximum (LGM) to present time, the vegetation model is forced with the 1-kyr snapshot outputs of the HadCM3 climate model, statistically downscaled at a spatial resolution of 0.5° and bias-corrected. The calculated distributions are essentially in equilibrium with climate, except for small delay times associated with biomass growth. These distributions are also compared directly with the potential (no dispersal limitation either) distributions obtained from species distribution modelling (MaxENT) for the same set of tree species and with the same climate forcing. Then, to simulate tree species under limitation by both climate and seed dispersal, the dispersal module is run transiently on a sub-grid at 100 m resolution to reproduce species dynamics over the 20,000 years from their LGM refugia (simulated by the DVM). The dispersal capacities are dependent on species productivity and survival simulated by the DVM for each1-kyr snapshot. The modelled dispersal distances are compared to genetic-based dispersal distances estimated in the project. [less ▲]

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See detailDistribution of Podocarpus latifolius/milanjianus from the Last Glacial Maximum to 2100 in Africa with the dynamic vegetation model CARAIB.
Dury, Marie ULiege; Henrot, Alexandra-Jane ULiege; Lézine, Anne-Marie et al

Conference (2018, March 27)

Podocarpus latifolius/milanjianus (same species according to genetics) is an endemic African species with populations in the western, eastern and southern parts of the continent. The current global ... [more ▼]

Podocarpus latifolius/milanjianus (same species according to genetics) is an endemic African species with populations in the western, eastern and southern parts of the continent. The current global warming threatens the conservation of the relict patches of this mountain evergreen species. During the Last Glacial Maximum (LGM), the species was certainly more largely distributed and present at lower elevations than today according to pollen data. At the beginning of the Holocene, Podocarpus moved upwards due to warmer conditions. The size of the populations might have collapsed abruptly at the end of the ”African Humid Period” at ca. 3,000 BP. Besides this general evolution, the palaeo-distribution of Podocarpus remains relatively unknown. The origin and connections between the eastern, southern and western Podocarpus forests are still not understood. In the framework of two related projects, AFRIFORD and VULPES, we use the CARAIB dynamic vegetation model, in parallel to genetic and palynologic analyses, to simulate the past and future dynamics of Podocarpus and to understand its current distribution. Projections of the HadCM3 climate model are used to reproduce climatic conditions in Africa from LGM (21,000 BP) to present time with a temporal resolution of 1 kyr. For the future (until 2100), several IPCC CMIP5 climate scenarios have been selected according to the quality of their reconstructed climate (temperature and precipitation) over sub-Saharan Africa for historical period. After interpolation to a 0.5° regular grid, we kept only past/future anomalies that we added to the GSWP3 (20 CR) climate data chosen as the reference for the historical period. Sub-continental simulations are performed with CARAIB forced by these climatic projections to simulate the net primary productivity of Podocarpus over time and space. In addition, CARAIB simulations are performed at higher resolution over a restricted region in southwestern Cameroon to identify potential microrefugia. [less ▲]

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See detailRefining species traits in a dynamic vegetation model to project the impacts of climate change on tropical trees in Central Africa
Dury, Marie ULiege; Mertens, L.; Fayolle, Adeline ULiege et al

in Forests (2018), 9(11),

African tropical ecosystems and the services they provide to human society suffer from an increasing combined pressure of land use and climate change. How individual tropical tree species respond to ... [more ▼]

African tropical ecosystems and the services they provide to human society suffer from an increasing combined pressure of land use and climate change. How individual tropical tree species respond to climate change remains relatively unknown. In this study, we refined the species characterization in the CARAIB (CARbon Assimilation In the Biosphere) dynamic vegetation model by replacing plant functional type morpho-physiological traits by species-specific traits. We focus on 12 tropical tree species selected for their importance in both the plant community and human society. We used CARAIB to simulate the current species net primary productivity (NPP), biomass and potential distribution and their changes in the future. Our results indicate that the use of species-specific traits does not necessarily result in an increase of predicted current NPPs. The model projections for the end of the century highlight the large uncertainties in the future of African tropical species. Projected changes in species distribution vary greatly with the general circulation model (GCM) and, to a lesser extent, with the concentration pathway. The question about long-term plant response to increasing CO2 concentrations also leads to contrasting results. In absence of fertilization effect, species are exposed to climate change and might lose 25% of their current distribution under RCP8.5 (12.5% under RCP4.5), considering all the species and climatic scenarios. The vegetation model projects a mean biomass loss of -21.2% under RCP4.5 and -34.5% under RCP8.5. Potential range expansions, unpredictable due to migration limitations, are too limited for offsetting range contraction. By contrast, if the long-term species response to increasing [CO2] is positive, the range reduction is limited to 5%. However, despite a mean biomass increase of 12.2%, a positive CO2 feedback might not prevent tree dieback. Our analysis confirms that species will respond differently to new climatic and atmospheric conditions, which may induce new competition dynamics in the ecosystem and affect ecosystem services. © 2018 by the authors. [less ▲]

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See detailGlobal crop production: adaptation options to temperature increase
Minoli, Sara; Elliott, Joshua; Ruane, Alex C et al

Poster (2018)

Climate change is already and will continue affecting the productivity of agricultural systems, therefore demanding for adaptation strategies to avoid production losses. Due to the complexity and ... [more ▼]

Climate change is already and will continue affecting the productivity of agricultural systems, therefore demanding for adaptation strategies to avoid production losses. Due to the complexity and heterogeneity of crop-climate-soil systems, adaptation options are mostly implemented and evaluated locally. Nevertheless, global-scale estimates are needed because e.g. the efficiency of adaptation measures needs to be discussed in the context of costs and opportunities elsewhere. Global gridded crop models (GGCMs) can be informative at both local and larger scales by consistently simulating the entire global crop-land while accounting at the same time for local conditions. Here we present the first systematic study on cropping systems adaptation to temperature increase based on a GGCMs ensemble sensitivity analysis. The models consistently implemented two management options that can alleviate impacts of temperature increase on major grain crops: first an adoption of new cultivars to maintain the original growing period (a measure to counteract accelerated crop phenology) and then a full irrigation (with the aim of avoiding increased water stress due to increased atmospheric vapor pressure deficit (VPD) under warming). We assess the effectiveness of these two options, as well as their combination, in avoiding yield losses of four major crops (maize, wheat, rice and soybean). First results show that, at the global aggregation, irrigation and the unaltered growing period both allow for increasing yields under most warming scenarios, and that the most positive effects occur when these strategies are combined. We also study how adaptation effectiveness varies across regions of the global crop land. In temperate regions a cultivar shift typically has positive effects by reducing yield losses and often even leads to fully maintaining or exceeding the baseline yield levels across various levels of warming. On the other hand, in warmer areas, such as the tropics, this strategy only shows limited effects, even when combined with irrigation and already at moderate warming levels. This suggests that in such environment temperature is already a strong limiting factor that cannot be alleviated by altered crop phenology. This poses a challenge to identify and model alternative adaptation strategies. Irrigation typically helps to increase yields in water-scarce growing environments, but this is also true for most baseline conditions. Irrigation becomes a true adaptation measure only if the yield increase is larger under warming than under baseline conditions. This can e.g. occur in regions where the additional warming leads to substantial increases in VPD. [less ▲]

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See detailHigh-resolution simulations of natural and agricultural ecosystems over Belgium with the CARAIB Dynamic Vegetation Model
Jacquemin, Ingrid ULiege; Dury, Marie ULiege; Henrot, Alexandra-Jane ULiege et al

Conference (2017, November 17)

CARAIB (for CARbon Assimilation In the Biosphere) is a state-of-the-art dynamic vegetation model (DVM), initially designed to study the role of the vegetation in the global carbon cycle and the vegetation ... [more ▼]

CARAIB (for CARbon Assimilation In the Biosphere) is a state-of-the-art dynamic vegetation model (DVM), initially designed to study the role of the vegetation in the global carbon cycle and the vegetation behavior as a function of climate and soil. Motivated by the requirements of ecosystem management and land use planning studies, CARAIB was recently improved so as to deal with both natural and agricultural ecosystems and at a high resolution of 1km over Belgium. A new module, for crops and meadows, was added in the model, which deals with the specific processes (phenology) and management (sowing, harvesting,…) of these ecosystems. The spatial and temporal validation was carried out with different data sources : agricultural statistics, eddy-covariance site, field measurements,… The addition of the crop module has led to the improvement of the surface scheme, from now on including dynamic land use and land cover information. As well as describes the evolution of physical and biological processes, CARAIB has become an interesting tool to assess the sustainability under climate change of the ecological systems, in particular by the approach of the ecosystem goods and services. Indeed, if some model outputs can be directly read as quantitative indicators of ecosystem services (e.g. carbon sequestration), we have translated some of them to get, e.g., the crop yield (from net primary productivity) or an estimation of the soil erosion for simulation at the parcel level (from runoff and parcels characteristics). But whether an ecosystem services or land use planning studies, the crucial point for CARAIB is the landscape dynamics, which is not considered by the model, in the absence of anthropogenic, economic and societal factors in the system. In order to overcome this lack, CARAIB is now coupled with an agent-based model (ABM), to compose a land surface dynamics (LSD) module. The productivity and growth of natural and managed vegetation is given by the DVM to the ABM, which determines the shifts in land use and land cover. The LSD module is able to represent the mutual interactions between ecological and socio-economic systems and thus, to assess the sustainability of the different climate and socio-economic scenarios tested. [less ▲]

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See detailHow do individual species and Plant Functional Type responses to environmental change differ in Dynamic Vegetation Models? - A forest stand analysis
Dury, Marie ULiege; Henrot, Alexandra-Jane ULiege; Jacquemin, Ingrid ULiege et al

Poster (2017, October 09)

Originally dedicated to simulate vegetation at the global scale, dynamic (global) vegetation models (D(G)VMs) classify vegetation into Plant Functional Types (PFTs) to represent the largest set of plant ... [more ▼]

Originally dedicated to simulate vegetation at the global scale, dynamic (global) vegetation models (D(G)VMs) classify vegetation into Plant Functional Types (PFTs) to represent the largest set of plant species. PFTs are clusters of species that share common morphological and physiological traits. However, PFT classification becomes surely too coarse to reflect the large diversity in plant species responses to climate and environmental changes, a critical point for biodiversity questions. Thus, some efforts focus now on applying DVMs at the species level refining the definition of morphophysiological parameters from initial PFT traits to specific traits collected or found in trait databases. What are the effects of using species-specific parameters? Do dynamic vegetation models better reproduce historical forest growth and mortality observed in monitored stands? How will individual species respond to future climate compared to PFTs? To study these questions, we used two process-based dynamic vegetation models CARAIB (Dury et al., 2011) as well as LPJ-GUESS (Smith et al., 2001), and compared their outputs. CARAIB has been previously adapted to model a set of 40 European tree species, differentiated by their specific traits, proper climatic requirements and tolerances. LPJ-GUESS features a detailed representation of climate sensitive tree species dynamics, resource competition and canopy structure (Hickler et al., 2012). The respective tree species are distinguished by taking differences in phenology, allometry and bioclimatic limits into account. Model simulations were performed in accordance with the experimental protocol of the COST Action PROFOUND (“Towards robust projections of European forests under climate change”) for several European forest stands selected in the project. We particularly focused on Fagus sylvatica stand in Sorø (Denmark), Picea abies stand in Solling (Germany) and Pinus sylvestris (and Picea abies) stands in Hyytiala (Finland). The experiments include site-specific soil characteristics, management practices (planting, thinning and harvest) and climate conditions. For the historical period (from planting year to 2014), besides local observations, simulations were also run with the original (0.5-degree spatial resolution) and locally bias-corrected (LBC) ISIMIP2B outputs of global climate models for testing the reliance of DVM results to the spatial resolution of climatic inputs. For the future period (2005-2100), vegetation models were driven by the ISIMIP2B climates under different Representative Concentration Pathways. The simulations at the PFT level were performed following the same protocol replacing the locally present species by their representative PFTs. The carbon and water fluxes obtained from the different experiments carried out with the two DVMs were compared with eddy-covariance data from each site. [less ▲]

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See detailThe response of Pacific Northwest evergreen coniferous forests to climate change: the case of Douglas fir explored with a dynamic vegetation model.
Dury, Marie ULiege; Rastogi, Bharat; Kim, John B. et al

Poster (2017, August 09)

Background/Question/Methods Climate warming is already affecting ecosystems in the Pacific Northwest (PNW). Decrease in ecosystem productivity and increase in mortality of some plant species induced by ... [more ▼]

Background/Question/Methods Climate warming is already affecting ecosystems in the Pacific Northwest (PNW). Decrease in ecosystem productivity and increase in mortality of some plant species induced by drought and disturbances have been reported. What will be the long-term response of vegetation to change in soil water content, in atmospheric CO2 concentration and in fire disturbances? We use the process-based dynamic vegetation model CARAIB which includes all these essential components to simulate present and future plant species distribution and functioning. We previously evaluated the ability of the vegetation model to reproduce the regional water and carbon cycling over the historical period using global Plant Functional Types. But, since individual species with a narrower bioclimatic spectrum than parent PFT might be more vulnerable to climate change, we now apply the vegetation model at the level of representative PNW species. Here, we focus on Douglas fir (Pseudotsuga menziesii), one of the most important and valuable timber trees of the world. Species physiological and structural parameters were progressively adapted from initial PFT traits to specific traits found in local or global trait databases (e.g., TRY database). For the historical period, the vegetation model is driven with the 1979-2014 meteorological dataset UIdaho MACA METDATA with a 1/24-degree (~4-km) spatial resolution and a daily temporal resolution. We simulate future conditions until 2100 using the UIdaho MACAv2-METDATA dataset, which includes downscaled CMIP5 projections from numerous GCMs. Results/Conclusions The model ability to reproduce the current spatial and temporal variations of PNW water and carbon stocks and fluxes has been formerly demonstrated using available datasets (e.g., National Biomass and Carbon Dataset, MODIS remote-sensed products, etc.). In the present research, we show that the model is in good agreement with the observations in regard to species occurrences (FIA plots) and functioning (eddy covariance sites). The modeled gross primary production (GPP) matches very well the measured GPP in Douglas-fir stands. Uncertainties remain regarding projected temperature and precipitation changes. Some climatic scenarios like the one generated by the CCSM4 model (which is among the best performers for historical PNW climate) project a warming and an emphasis of current precipitation regime, wetter winter and drier summer (especially in the lowlands). According to CARAIB, the resulting lower soil water content might not strongly change the spatial distribution of Douglas fir, but might impact its productivity. We also evaluate mortality induced by changes in drought frequency as well as in fire risk. [less ▲]

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See detailEstimation des bilans hydriques présent et futur ainsi que de leur impact sur les rendements agricoles en Afrique du Nord et de l'Ouest à l'aide d'un modèle de végétation dynamique
Dury, Marie ULiege; Jacquemin, Ingrid ULiege; Henrot, Alexandra-Jane ULiege et al

Conference (2017, March 29)

Climate change is affecting agriculture all over the world with dramatic consequences in developing countries already affected by limited water resources. Unfortunately, the lack of a consistent coverage ... [more ▼]

Climate change is affecting agriculture all over the world with dramatic consequences in developing countries already affected by limited water resources. Unfortunately, the lack of a consistent coverage of hydrological data (precipitation, soil water content, etc.), especially in those regions, makes difficult a good knowledge of the current conditions and, thus, prevents any planning for the future. Therefore, ecosystem process-based models are interesting tools to represent the water balance of terrestrial ecosystems and provide an overview of the current and future hydrological conditions. Here, we use the CARAIB (CARbon Assimilation In the Biosphere; Dury et al., 2011) dynamic vegetation model (DVM) to evaluate current and future soil water availability and assess potential impacts of its reduction on crop yields. CARAIB is a state-of-the-art DVM with various modules dealing with (i) soil hydrology, (ii) photosynthesis/stomatal regulation, (iii) carbon allocation and biomass growth, (iv) litter/soil carbon dynamics, (v) vegetation cover dynamics, (vi) seed dispersal, and (vii) vegetation fires. Climate and atmospheric CO2 are the primary inputs. Within the VOTES project (Fontaine et al., 2014) and the GGCMI intercomparison (Global Gridded Crop Model Intercomparison), the model has been improved to include crops and meadows (Minet et al., 2015), and some modules have been written to translate model outputs into quantitative indicators of ecosystem services (e.g., to evaluate crop yield from net primary productivity, to calculate soil erosion from runoff and slope or to apply irrigation water). In this contribution, we focus on four crop species (maize, rice, soy and spring wheat) over North and West Africa. We use historical climate and future projections from the ISI-MIP2 model intercomparison (Inter-Sectoral Impact Model Intercomparison Project). Historical climate is PGMFD v.2.1 (NCEP/NCAR Reanalysis 1) 1901-2012 time series. Future change in temperature and precipitation are produced over the 21st century by CMIP5 general circulation model simulations that were bias-corrected in the framework of the ISI-MIP2 project. Simulations of the vegetation model are performed at 0.5° spatial resolution under two water scenarios: a water-limited (precipitation only) and a full irrigation (water supplied to reach field capacity). In the model, the soil water available for plant (ASW) is expressed as the fraction between the actual soil water and the water available for plant growth at field capacity (FC): ASW = (SW-WP)/(FC-WP) with SW being the actual soil water and WP the wilting point. Under the first scenario, the soil water deficit and its impacts on crop production are evaluated. The second scenario allows an evaluation of the amount of irrigation water necessary to fulfill crop requirements. This kind of study can help in the identification of agricultural areas currently vulnerable or which might be exposed in the future. It can also be useful to optimise water resource management in African countries. [less ▲]

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See detailSystematic global gridded crop simulations for improved understanding of climate change impacts on agricultural productivity
Müller, Christoph; Elliott, Joshua; Dury, Marie ULiege et al

Poster (2017, March 27)

The Global Gridded Crop Model Intercomparison (GGCMI) of the Agricultural Model Intercomparison and Improvement Project (AgMIP) brings together a diverse international community of crop modelers for ... [more ▼]

The Global Gridded Crop Model Intercomparison (GGCMI) of the Agricultural Model Intercomparison and Improvement Project (AgMIP) brings together a diverse international community of crop modelers for climate impact assessment, model intercomparison and improvement at the global scale. After conducting a fast-track analysis of climate change impacts on agricultural productivity in the framework of the InterSectoral Impact Model Intercomparison Project (ISIMIP)[1], GGCMI protocols[2] established a benchmark for model evaluation and analyzed model performance and different sources of uncertainty[3]. In the current phase, GGCMI conducts a large input-sensitivity analysis that aims to enhance understanding of how models work and to characterize models by sensitivity to drivers: Carbon dioxide, Temperatures, Water supply, Nitrogen supply and Adaptation. Modelers were asked to supply up to 1512 global 31-year simulations for five different crops: maize, rice, soybean, spring wheat and winter wheat. [less ▲]

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See detailModelling past and present distributions of tropical African biomes and species using a dynamic vegetation model.
Dury, Marie ULiege; Doutreloup, Sébastien ULiege; Hardy, Olivier et al

Poster (2017, February 08)

In the framework of the AFRIFORD project (Genetic and paleoecological signatures of African rainforest dynamics: pre-adapted to change?, http://www.ulb.ac.be/facs/sciences/afriford/), we used the CARAIB ... [more ▼]

In the framework of the AFRIFORD project (Genetic and paleoecological signatures of African rainforest dynamics: pre-adapted to change?, http://www.ulb.ac.be/facs/sciences/afriford/), we used the CARAIB dynamic vegetation model to simulate past and present distributions of tropical African vegetation at the biome and species levels to better project and understand future dynamics. We studied individual species (e.g., Afzelia africana, Pericopsis elata, etc) for which we determined climatic requirements and gathered specific traits. To perform palaeovegetation reconstructions, we used outputs of snapshot climate simulations (e.g., CNRM-CM5, FGOALS-g2 and MRI-CGCM5 global climatic models) from the PaleoModelling Intercomparison Project (PMIP3, https://pmip3.lsce.ipsl.fr/) for the mid-Holocene (6 ka) and the Last Glacial Maximum (LGM, 21 ka). These global climatic outputs were downscaled at a 0.45° spatial resolution over Equatorial Africa using the MAR regional climate model (RCM). For current conditions, the RCM was nested in different historical climate datasets. We compared modelled species distributions with species occurrences from different databases for present and with palaeorecords for past periods. MAR regional climate simulations notably allow CARAIB to reproduce the Dahomey Gap separating the Upper and Lower Guinean forests in West Africa in present biome distribution. The vegetation model also simulates LGM rainforest distribution in agreement with hypothetical glacial rainforest refuge areas inferred from palaeorecords. [less ▲]

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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 detailRefining plant traits in vegetation models using forest inventory and LAI measurements. An application to the modelling of Cedrus atlantica in the Rif Mountains with the CARAIB model
Henrot, Alexandra-Jane ULiege; Hambuckers, Alain ULiege; François, Louis ULiege et al

Conference (2017)

It appears today established that climate change will alter biodiversity, since the migration speed of many species, especially plants, are presumably too small to follow climate change. Mountain ... [more ▼]

It appears today established that climate change will alter biodiversity, since the migration speed of many species, especially plants, are presumably too small to follow climate change. Mountain ecosystem floras of Mediterranean regions are particularly vulnerable to the climatic threat, because they combine high ecosystem diversity and large proportion of endemic species, with the risk of reaching the summits of the mountains which would limit their migration. Moreover, these environments are often strongly impacted by man. Being able to identify and predict the areas favourable to the species – microrefugia - becomes crucial in view of the fragmentation of the space devoted to their conservation. Dynamic vegetation models (DVMs) are well-designed tools for performing such projections, since they incorporate the physiological effects of CO2. However, they are usually run at the plant functional type level (PFT), whereas conservation studies require specific projections for each individual species. Thus, some efforts focus now on applying DVMs at species level, refining the definition of morphophysiological parameters from initial PFT traits to specific traits collected in the field or found in trait databases. Here we simulated the modern distribution of Cedrus atlantica, an endangered species of the north Africa mountains with the CARAIB DVM (Dury et al., iForest - Biogeosciences and Forestry, 4:82-99, 2011), over the Rif Mountains. Model results in terms of biomass and NPP are evaluated against data coming from forest inventory and LAI measurements. Morphological traits of C. atlantica derived from plant material collected in situ (such as specific leaf area, C:N ratio of leaves, etc) are adapted in the model simulation. CARAIB is run at high resolution using either climatic inputs derived from the Climate Research Unit climate dataset combined with WorldClim climatology at 30 arc sec or the ouputs of a 5 km resolution simulation of the regional climate model MAR (Fettweis et al., The Cryosphere, 7 :469-489, 2013) over the focal area. [less ▲]

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See detailMiddle Miocene climate and vegetation models and their validation with proxy data
Henrot, Alexandra-Jane ULiege; Utescher, Torsten; Erdei, Boglarka et al

in Palaeogeography, Palaeoclimatology, Palaeoecology (2017), 467

The Miocene is a relatively recent epoch of the Earth's history with warmer climate than today, particularly during the middle Miocene Climatic Optimum (MMCO, approximately 17–15 Ma). Although the cause ... [more ▼]

The Miocene is a relatively recent epoch of the Earth's history with warmer climate than today, particularly during the middle Miocene Climatic Optimum (MMCO, approximately 17–15 Ma). Although the cause of the warming is probably not only attributable to CO2, but also to changes in orography and configuration of ocean gateways, this time interval represents an ideal case study to test the ability of climate models to simulate warm climates comparable to those that the Earth may experience in the near future. However, even with higher than present-day CO2 concentrations, the MMCO warming inferred from terrestrial proxy data has been difficult to reproduce in climate models. Since fossil flora do not provide direct information on climate, but on flora and vegetation, climate model results are generally compared to climate reconstructions obtained from the fossil flora. In this study, we apply an alternative method by simulating palaeovegetation from the outputs of the climate model, using a dynamic vegetation model. Model vegetation reconstruction can then be compared to the vegetation cover indicated by the fossil flora record at the various localities, provided that a common classification of plant functional types (PFTs) is used for the data and the model. Here, we reconstruct the vegetation of the middle Miocene with the global dynamic vegetation model CARAIB, using the climatologies derived from five atmospheric general circulation models. The reliability of the simulations is examined on a presence/absence basis of PFTs by comparison of vegetation reconstructions to palaeoflora data recorded in the Northern Hemisphere and the Tropics. This comparison provides an overall agreement around 60% between model and data, when all sites and tree types are considered. Three model simulations out of five show to be better at predicting the absence than the presence. The presence of warm-temperate mixed forests in the middle latitudes, dominated by broadleaved deciduous warm temperate and subtropical trees is generally well reproduced in CARAIB simulations. However, poor agreement is obtained for the presence of tropical PFTs out of the Tropics and for warm PFTs at latitudes northward of 50°N, where climate models remain too cold to produce assemblages of trees consistent with the data. Nevertheless, the model–data comparison performed here highlights several mismatches that could result not only from missing feedbacks in the climate simulations, but also from the data. The results of the likelihood analysis on presence/absence of PFTs illustrate the uncertainties in the PFT classification of the Neogene floral records. The coexistence of some PFTs in the palaeovegetation data is impossible to reproduce in the vegetation model simulations because of the climatic definition of the modern PFTs. This result indicates either a bias in the identification of modern analogues for fossil plant taxa, or a possible evolution of environmental requirements of certain plants. [less ▲]

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See detailBenchmarking carbon fluxes of the ISIMIP2a biome models
Chang, Jinfeng; Ciais, Philippe; Wang, Xuhui et al

in Environmental Research Letters (2017), 12

The purpose of this study is to evaluate the eight ISIMIP2a biome models against independent estimates of long-term net carbon fluxes (i.e. Net Biome Productivity, NBP) over terrestrial ecosystems for the ... [more ▼]

The purpose of this study is to evaluate the eight ISIMIP2a biome models against independent estimates of long-term net carbon fluxes (i.e. Net Biome Productivity, NBP) over terrestrial ecosystems for the recent four decades (1971–2010). We evaluate modeled global NBP against 1) the updated global residual land sink (RLS) plus land use emissions (E LUC) from the Global Carbon Project (GCP), presented as R + L in this study by Le Quéré et al (2015), and 2) the land CO2 fluxes from two atmospheric inversion systems: Jena CarboScope s81_v3.8 and CAMS v15r2, referred to as F Jena and F CAMS respectively. The model ensemble-mean NBP (that includes seven models with land-use change) is higher than but within the uncertainty of R + L, while the simulated positive NBP trend over the last 30 yr is lower than that from R + L and from the two inversion systems. ISIMIP2a biome models well capture the interannual variation of global net terrestrial ecosystem carbon fluxes. Tropical NBP represents 31 ± 17% of global total NBP during the past decades, and the year-to-year variation of tropical NBP contributes most of the interannual variation of global NBP. According to the models, increasing Net Primary Productivity (NPP) was the main cause for the generally increasing NBP. Significant global NBP anomalies from the long-term mean between the two phases of El Niño Southern Oscillation (ENSO) events are simulated by all models (p < 0.05), which is consistent with the R + L estimate (p = 0.06), also mainly attributed to NPP anomalies, rather than to changes in heterotrophic respiration (Rh). The global NPP and NBP anomalies during ENSO events are dominated by their anomalies in tropical regions impacted by tropical climate variability. Multiple regressions between R + L, F Jena and F CAMS interannual variations and tropical climate variations reveal a significant negative response of global net terrestrial ecosystem carbon fluxes to tropical mean annual temperature variation, and a non-significant response to tropical annual precipitation variation. According to the models, tropical precipitation is a more important driver, suggesting that some models do not capture the roles of precipitation and temperature changes adequately. [less ▲]

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