References of "François, Louis"
     in
Bookmark and Share    
Full Text
See detailSimulating and analysing climate change impacts on crop yields in Morocco using the CARAIB dynamic vegetation model driven by Med- CORDEX projections
Loudiyi, Iliass ULiege; Jacquemin, Ingrid ULiege; Tychon, Bernard ULiege et al

Conference (2020, May 08)

Morocco, by its geographical position and its climate, is strongly affected by climate change and presents an ever-increasing vulnerability. In fact, the country's economy, being very dependent on ... [more ▼]

Morocco, by its geographical position and its climate, is strongly affected by climate change and presents an ever-increasing vulnerability. In fact, the country's economy, being very dependent on agriculture, would be greatly affected. It is therefore necessary to further develop knowledge about climate change and strengthen forcasting systems for predicting the impacts of climate change. The agriculture in Morocco is largely dominated by rainfed crops and therefore dependent on pluviometry. According to the Global Yield Gap Atlas, about 43% of arable land is devoted to cereals, 7% to plantation crops (olives, almonds, citrus, grapes, dates), 3% to pulses, 2% to forage, 2% to vegetables, 2% to industrial crops (sugar beets, sugar cane, cotton) and oilseeds, and 42% is fallow. In this project we are going to focus on cereals, olives, potatoes and sugar beets. Regarding the climate, Morocco is characterized by a wide variety of topographies ranging from mountains to plains, oasis and Saharan dunes. For this reason, the country experiences diverse climatic conditions with large spatial and intra- and inter-annual variability of precipitation. Morocco faces irregular rain patterns, cold spells and heat waves increasingly resulting in droughts, which significantly affects agriculture. Our research, funded by a bilateral project of Wallonie-Bruxelles International, aims to study the response of Moroccan agriculture to climate change, using the dynamic vegetation model CARAIB (CARbon Assimilation In the Biosphere) developed within the Unit for Modelling of Climate and Biogeochemical Cycles (UMCCB) of the University of Liège. This spatial model includes crops and natural vegetation and may react dynamically to land use changes. Originally constructed to study vegetation dynamics and carbon cycle, it includes coupled hydrological, biogeochemical, biogeographical and fire modules. These modules respectively describe the exchange of water between the atmosphere, the soil and the vegetation, the photosynthetic production and the evolution of carbon stocks and fluxes in this vegetation-soil system. The biogeographical module describes, for natural vegetation, the establishment, growth, competition, mortality, and regeneration of plant species, as well as the occurrence and propagation of fires. For crops, a specific module describes basic management (sowing, harvest, rotation) and phenological phases. Model simulations are performed across north-west Morocco, where the crops activities are important, by using different input data. The timeline of simulations is divided in two periods: past (from 1901 to 2018[LF1] ) and future (from 2019 to 2100). For the past period, we are using high resolution (30 arc sec) gridded climate data derived from WorldClim (climatology) and interpolated anomalies from Climate Research Unit CRU (trend and variability). For the future period, we use interpolated and bias-corrected fields from a regional climate model (ALADIN-Climate) from the Med-CORDEX initiative run at a spatial resolution of 12 km and for three different Representative Concentration Pathway scenarios (RCP2.6, RCP4.5 and RCP8.5). [less ▲]

Detailed reference viewed: 54 (3 ULiège)
Full Text
Peer Reviewed
See detailThe GGCMI Phase 2 experiment: Global gridded crop model simulations under uniform changes in CO2, temperature, water, and nitrogen levels (protocol version 1.0)
Franke, J. A.; Müller, C.; Elliott, J. et al

in Geoscientific Model Development (2020), 13(5), 2315-2336

Concerns about food security under climate change motivate efforts to better understand future changes in crop yields. Process-based crop models, which represent plant physiological and soil processes ... [more ▼]

Concerns about food security under climate change motivate efforts to better understand future changes in crop yields. Process-based crop models, which represent plant physiological and soil processes, are necessary tools for this purpose since they allow representing future climate and management conditions not sampled in the historical record and new locations to which cultivation may shift. However, process-based crop models differ in many critical details, and their responses to different interacting factors remain only poorly understood. The Global Gridded Crop Model Intercomparison (GGCMI) Phase 2 experiment, an activity of the Agricultural Model Intercomparison and Improvement Project (AgMIP), is designed to provide a systematic parameter sweep focused on climate change factors and their interaction with overall soil fertility, to allow both evaluating model behavior and emulating model responses in impact assessment tools. In this paper we describe the GGCMI Phase 2 experimental protocol and its simulation data archive. A total of 12 crop models simulate five crops with systematic uniform perturbations of historical climate, varying CO2, temperature, water supply, and applied nitrogen ("CTWN") for rainfed and irrigated agriculture, and a second set of simulations represents a type of adaptation by allowing the adjustment of growing season length. We present some crop yield results to illustrate general characteristics of the simulations and potential uses of the GGCMI Phase 2 archive. For example, in cases without adaptation, modeled yields show robust decreases to warmer temperatures in almost all regions, with a nonlinear dependence that means yields in warmer baseline locations have greater temperature sensitivity. Inter-model uncertainty is qualitatively similar across all the four input dimensions but is largest in high-latitude regions where crops may be grown in the future. © Author(s) 2020. [less ▲]

Detailed reference viewed: 32 (3 ULiège)
Full Text
Peer Reviewed
See detailPronounced and unavoidable impacts of low-end global warming on northern high-latitude land ecosystems
Ito, A.; Reyer, C. P. O.; Gädeke, A. et al

in Environmental Research Letters (2020), 15(4),

Arctic ecosystems are particularly vulnerable to climate change because of Arctic amplification. Here, we assessed the climatic impacts of low-end, 1.5 °C, and 2.0 °C global temperature increases above ... [more ▼]

Arctic ecosystems are particularly vulnerable to climate change because of Arctic amplification. Here, we assessed the climatic impacts of low-end, 1.5 °C, and 2.0 °C global temperature increases above pre-industrial levels, on the warming of terrestrial ecosystems in northern high latitudes (NHL, above 60 °N including pan-Arctic tundra and boreal forests) under the framework of the Inter-Sectoral Impact Model Intercomparison Project phase 2b protocol. We analyzed the simulated changes of net primary productivity, vegetation biomass, and soil carbon stocks of eight ecosystem models that were forced by the projections of four global climate models and two atmospheric greenhouse gas pathways (RCP2.6 and RCP6.0). Our results showed that considerable impacts on ecosystem carbon budgets, particularly primary productivity and vegetation biomass, are very likely to occur in the NHL areas. The models agreed on increases in primary productivity and biomass accumulation, despite considerable inter-model and inter-scenario differences in the magnitudes of the responses. The inter-model variability highlighted the inadequacies of the present models, which fail to consider important components such as permafrost and wildfire. The simulated impacts were attributable primarily to the rapid temperature increases in the NHL and the greater sensitivity of northern vegetation to warming, which contrasted with the less pronounced responses of soil carbon stocks. The simulated increases of vegetation biomass by 30-60 Pg C in this century have implications for climate policy such as the Paris Agreement. Comparison between the results at two warming levels showed the effectiveness of emission reductions in ameliorating the impacts and revealed unavoidable impacts for which adaptation options are urgently needed in the NHL ecosystems. © 2020 The Author(s). Published by IOP Publishing Ltd. [less ▲]

Detailed reference viewed: 34 (2 ULiège)
Full Text
Peer Reviewed
See detailOligocene vegetation of Europe and western Asia—Diversity change and continental patterns reflected by plant functional types
Utescher, T.; Erdei, B.; François, Louis ULiege et al

in Geological Journal (2020)

Spatial vegetation patterns potentially reflect coeval continental climate variations which are also impacted by palaeogeographical settings. Plant functional types (PFTs) and their distribution ... [more ▼]

Spatial vegetation patterns potentially reflect coeval continental climate variations which are also impacted by palaeogeographical settings. Plant functional types (PFTs) and their distribution, frequently applied in ecological studies and biome modelling, serve as a tool for reconstructing palaeovegetation units and ultimately tracing palaeoecological/climate gradients. Earlier quantitative studies focusing on distribution patterns of PFTs and designed to put forward data-model comparisons were carried out on well-dated Middle and Late Miocene floras. Moreover, the PFT approach has been successfully applied to reconstruct Eocene vegetation patterns in several time slices at a global scale as well as in regional vegetation reconstructions throughout the Cenozoic. In the current study, a PFT approach with 41 different classes is applied on Rupelian and Chattian fossil floras of Europe and western Asia to infer spatial vegetation differences across the study area. A comprehensive palaeobotanical record including ~163 macro- (leaves, fruits and seeds) and microfloras was compiled. The floristic components of these palaeofloras are translated to PFTs including herbaceous to arboreal classes. The PFTs are defined using traits and climatic thresholds of key taxa, and comprise species assigned by morphological and phenological features with respect to the related ecosystem. Diversity values of each PFT are calculated for the fossil floras and spatial gradients over western Eurasia are investigated for the Rupelian and Chattian. PFT diversity maps and transects for both time slices reveal basic patterns of the vegetational structure at the continental scale. It is shown that in both time slices studied tropical and broadleaved evergreen PFTs were more diverse in the West and at lower latitudes. Consistently with the global climate evolution as known from marine archives and regional continental records their level was higher in the Rupelian compared to the Chattian. All over low diversities of xeric PFTs coincide with the previously assumed dominance of humid climate conditions in western Eurasia throughout the Oligocene, however, the reconstructed spatial gradients suggest somewhat drier conditions to the southwest and southeast of the study area. © 2020 The Authors. Geological Journal published by John Wiley & Sons Ltd [less ▲]

Detailed reference viewed: 24 (3 ULiège)
Full Text
See detailChapter 4. Multidisciplinary approaches for conservation issues
Cheddadi, Rachid; Sarmiento, Fausto; Hambuckers, Alain ULiege et al

in Frolich, Larry M.; Sarmiento, Fausto (Eds.) The Elgar Companion to Geography, Transdisciplinarity and Sustainability (2020)

Detailed reference viewed: 56 (16 ULiège)
Full Text
Peer Reviewed
See detailTRY plant trait database – enhanced coverage and open access
Kattge, Jens; Bönisch, Gerhard; Díaz, Sandra et al

in Global Change Biology (2020), 26(1), 119-188

Abstract Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic ... [more ▼]

Abstract Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives. [less ▲]

Detailed reference viewed: 96 (8 ULiège)
Full Text
Peer Reviewed
See detailGlobal response patterns of major rainfed crops to adaptation by maintaining current growing periods and irrigation
Minoli, Sara; Müller, Christoph; Elliott, Joshua et al

in Earth's Future (2019), 7(12), 1464-1480

Increasing temperature trends are expected to impact yields of major field crops by affectingvarious plant processes, such as phenology, growth, and evapotranspiration. However, future ... [more ▼]

Increasing temperature trends are expected to impact yields of major field crops by affectingvarious plant processes, such as phenology, growth, and evapotranspiration. However, future projectionstypically do not consider the effects of agronomic adaptation in farming practices. We use an ensemble ofseven Global Gridded Crop Models to quantify the impacts and adaptation potential of field crops underincreasing temperature up to 6 K, accounting for model uncertainty. We find that without adaptation, thedominant effect of temperature increase is to shorten the growing period and to reduce grain yields andproduction. We then test the potential of two agronomic measures to combat warming-induced yieldreduction: (i) use of cultivars with adjusted phenology to regain the reference growing period duration and(ii) conversion of rainfed systems to irrigated ones inorder to alleviate the negative temperature effects thatare mediated by crop evapotranspiration. We find that cultivar adaptation can fully compensate globalproduction losses up to2Koftemperature increase, with larger potentials in continental and temperateregions. Irrigation could also compensate production losses, but its potential is highest in arid regions,where irrigation expansion would be constrained by water scarcity. Moreover, we discuss that irrigation isnot a true adaptation measure but rather an intensification strategy, as it equally increases productionunder any temperature level. In the tropics, even when introducing both adapted cultivars and irrigation,crop production declines already at moderate warming, making adaptation particularly challenging inthese areas. (c) The Authors [less ▲]

Detailed reference viewed: 19 (4 ULiège)
Full Text
Peer Reviewed
See detailUtilisation du modèle dynamique de végétation CARAIB pour simuler les rendements en Belgique : validation et projections à l'horizon 2035
Jacquemin, Ingrid ULiege; Berckmans, Julie; Henrot, Alexandra-Jane ULiege et al

Poster (2019, September)

Le modèle CARAIB (CARbon Assimilation In the Biosphere) est un modèle dynamique de végétation initialement développé pour étudier le comportement de la végétation naturelle, tant son rôle dans le cycle ... [more ▼]

Le modèle CARAIB (CARbon Assimilation In the Biosphere) est un modèle dynamique de végétation initialement développé pour étudier le comportement de la végétation naturelle, tant son rôle dans le cycle global du carbone que sa réponse aux changements de climat et de sol. Afin de pouvoir répondre à de nouveaux challenges (comme l’étude des rétroactions climat-végétation ou encore de l’évaluation des services écosystémiques), le modèle a été doté d’un nouveau module lui permettant de couvrir l’ensemble de la végétation, naturelle et celle dite « managée » comme les cultures. Par conséquent, CARAIB devient un outil intéressant pour l’analyse du risque encouru par la végétation, et tout particulièrement pour les cultures agricoles, dans un contexte de changement climatique. Mais avant toute chose, il convient de procéder à la validation du module culture. Afin d’évaluer la variation temporelle, nous avons confronté les sorties du modèle avec des données de terrain venant des sites de mesure des flux d’eddy-covariance du réseau Fluxnet. Nous avons notamment comparé les flux de carbone (la GPP pour « Gross Primary Production » et la NEE pour « Net Ecosystem Exchange ») et l’évapotranspiration simulés par le modèle, avec les observations venant de plusieurs sites, dont celui de Lonzée en Belgique et de Grignon en France. A eux seuls, ces deux sites permettent de couvrir les 6 cultures proposées par CARAIB, à savoir le froment et l’orge d’hiver, le maïs, les pommes de terre, les betteraves sucrières et le colza. Pour l’évaluation de la variabilité spatiale, nous avons procédé à des simulations sur l’ensemble de la Belgique, où le modèle a été forcé par les sorties du modèle régional ALARO de l’Institut Royal Météorologique pour le passé récent, à 4km de résolution. Finalement, nous avons forcé le modèle CARAIB, toujours avec les sorties du modèle ALARO à 4km, mais cette fois pour les scénarios futurs RCP4.5 et 8.5, pour l’horizon 2035. Au-delà de l’effet fertilisant du CO2 atmosphérique croissant qui impacte positivement les rendements, nous pouvons d’ores et déjà mettre en évidence une variabilité interannuelle plus importante pour l’ensemble des cultures à l’exception du maïs. [less ▲]

Detailed reference viewed: 34 (6 ULiège)
Full Text
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 ▲]

Detailed reference viewed: 68 (9 ULiège)
Full Text
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 ▲]

Detailed reference viewed: 134 (9 ULiège)
Full Text
Peer Reviewed
See detailEstimation of present and future soil water balance and its impacts on wheat yields in African regions north of the equator using a dynamic vegetation model
Dury, Marie ULiege; Jacquemin, Ingrid ULiege; Henrot, Alexandra-Jane ULiege et al

in Geo-Eco-Trop: Revue Internationale de Géologie, de Géographie et d'Écologie Tropicales (2019), 43(3), 317-326

Climate warming and growing population are hot topics for agriculture and food security in Africa. In this context, the CARAIB dynamic vegetation model is run over Africa north of the equator to project ... [more ▼]

Climate warming and growing population are hot topics for agriculture and food security in Africa. In this context, the CARAIB dynamic vegetation model is run over Africa north of the equator to project future soil water balance and its impact on yields of wheat (a culture whose distribution is projected to increase rapidly given the huge demand on the continent). Forced with different climate and CO2 concentration scenarios, the uncertainties in yield projections are large. Assuming CO2 effects, model results indicate a potential stimulation of wheat growth overcoming negative climate change impacts with yield gains around 20 % in sub-Saharan regions above the equator (up to 40 % in Eastern Africa). Without CO2 fertilization, negative yield anomalies are projected under future climate trends (warming and drying). Since the agronomic adaptation of African agriculture is an important source of uncertainties, the yield-increasing effect of irrigation is also analysed. [less ▲]

Detailed reference viewed: 20 (2 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 ▲]

Detailed reference viewed: 51 (6 ULiège)
Full Text
Peer Reviewed
See detailBrazilian montane rainforest expansion induced by Heinrich Stadial 1 event
Pinaya, Jorge L. D.; Cruz, Francisco W.; Ceccantini, Gregório C. T. et al

in Scientific Reports (2019), 9(1), 17912

The origin of modern disjunct plant distributions in the Brazilian Highlands with strong floristic affinities to distant montane rainforests of isolated mountaintops in the northeast and northern Amazonia ... [more ▼]

The origin of modern disjunct plant distributions in the Brazilian Highlands with strong floristic affinities to distant montane rainforests of isolated mountaintops in the northeast and northern Amazonia and the Guyana Shield remains unknown. We tested the hypothesis that these unexplained biogeographical patterns reflect former ecosystem rearrangements sustained by widespread plant migrations possibly due to climatic patterns that are very dissimilar from present-day conditions. To address this issue, we mapped the presence of the montane arboreal taxa Araucaria, Podocarpus, Drimys, Hedyosmum, Ilex, Myrsine, Symplocos, and Weinmannia, and cool-adapted plants in the families Myrtaceae, Ericaceae, and Arecaceae (palms) in 29 palynological records during Heinrich Stadial 1 Event, encompassing a latitudinal range of 30°S to 0°S. In addition, Principal Component Analysis and Species Distribution Modelling were used to represent past and modern habitat suitability for Podocarpus and Araucaria. The data reveals two long-distance patterns of plant migration connecting south/southeast to northeastern Brazil and Amazonia with a third short route extending from one of them. Their paleofloristic compositions suggest a climatic scenario of abundant rainfall and relative lower continental surface temperatures, possibly intensified by the effects of polar air incursions forming cold fronts into the Brazilian Highlands. Although these taxa are sensitive to changes in temperature, the combined pollen and speleothems proxy data indicate that this montane rainforest expansion during Heinrich Stadial 1 Event was triggered mainly by a less seasonal rainfall regime from the subtropics to the equatorial region. [less ▲]

Detailed reference viewed: 24 (3 ULiège)
Full Text
Peer Reviewed
See detailDynamics and evolution of Turgay‐type vegetation in Western Siberia throughout the early Oligocene to earliest Miocene—a study based on diversity of plant functional types in the carpological record
Popova, Svetlana; Utescher, Torsten; Gromyko, Dimitry et al

in Journal of Systematics and Evolution (2019), 57(2), 129-141

Based on ecospectra of 66 published carpofloras we study dynamics and evolution of Turgay vegetation in Western Siberia during the early Oligocene to earliest Miocene. The ecospectra are obtained using a ... [more ▼]

Based on ecospectra of 66 published carpofloras we study dynamics and evolution of Turgay vegetation in Western Siberia during the early Oligocene to earliest Miocene. The ecospectra are obtained using a Plant Functional Type (PFT) classification system comprising 26 herbaceous to arboreal PFTs. The carpofloras originate from seven floristic levels covering the time‐span from the Rupelian to early Aquitanian. Key elements of these levels are documented based on original collection materials. Although impacted by local edaphic conditions, the ecospectra can be interpreted in terms of changing vegetation. Our data show that warm temperate mesophytic, mixed conifer‐broad‐leaved deciduous forest assemblages persisted throughout the Oligocene and earliest Miocene in this core area of Turgai type vegetation. This is in line with comparatively stable climate conditions persisting in the studied time‐span, showing a minor temperature decline and coeval moderate increase in seasonality and precipitation. Concurrently, the reconstructed ecospectra contradict significant continental drying throughout the Oligocene and earliest Miocene. Spatial variability of the proportions of PFTs within the single floristic horizons primarily reflects local edaphic conditions. High diversities of PFTs characteristic for swamp vegetation are mainly confined to the early Oligocene and have a regional focus. Our results indicate that taxonomical diversity, particularly concerning mesic herbs and deciduous shrubs and trees, increased towards the end of the Oligocene. This increase in biodiversity probably can be attributed to an increase in rainfall and extension of terrestrial habitats after the final retreat of the Paratethys. [less ▲]

Detailed reference viewed: 52 (5 ULiège)
Full Text
Peer Reviewed
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)
Full Text
Peer Reviewed
See detailTree mortality submodels drive simulated long-term forest dynamics: assessing 15 models from the stand to global scale
Bugmann, H.; Seidl, R.; Hartig, F. et al

in Ecosphere (2019), 10(2),

Models are pivotal for assessing future forest dynamics under the impacts of changing climate and management practices, incorporating representations of tree growth, mortality, and regeneration ... [more ▼]

Models are pivotal for assessing future forest dynamics under the impacts of changing climate and management practices, incorporating representations of tree growth, mortality, and regeneration. Quantitative studies on the importance of mortality submodels are scarce. We evaluated 15 dynamic vegetation models (DVMs) regarding their sensitivity to different formulations of tree mortality under different degrees of climate change. The set of models comprised eight DVMs at the stand scale, three at the landscape scale, and four typically applied at the continental to global scale. Some incorporate empirically derived mortality models, and others are based on experimental data, whereas still others are based on theoretical reasoning. Each DVM was run with at least two alternative mortality submodels. Model behavior was evaluated against empirical time series data, and then, the models were subjected to different scenarios of climate change. Most DVMs matched empirical data quite well, irrespective of the mortality submodel that was used. However, mortality submodels that performed in a very similar manner against past data often led to sharply different trajectories of forest dynamics under future climate change. Most DVMs featured high sensitivity to the mortality submodel, with deviations of basal area and stem numbers on the order of 10–40% per century under current climate and 20–170% under climate change. The sensitivity of a given DVM to scenarios of climate change, however, was typically lower by a factor of two to three. We conclude that (1) mortality is one of the most uncertain processes when it comes to assessing forest response to climate change, and (2) more data and a better process understanding of tree mortality are needed to improve the robustness of simulated future forest dynamics. Our study highlights that comparing several alternative mortality formulations in DVMs provides valuable insights into the effects of process uncertainties on simulated future forest dynamics. © 2019 The Authors. [less ▲]

Detailed reference viewed: 40 (12 ULiège)
Full Text
Peer Reviewed
See detailState-of-the-art global models underestimate impacts from climate extremes
Schewe, J.; Gosling, S. N.; Reyer, C. et al

in Nature Communications (2019), 10(1), 1005

Global impact models represent process-level understanding of how natural and human systems may be affected by climate change. Their projections are used in integrated assessments of climate change. Here ... [more ▼]

Global impact models represent process-level understanding of how natural and human systems may be affected by climate change. Their projections are used in integrated assessments of climate change. Here we test, for the first time, systematically across many important systems, how well such impact models capture the impacts of extreme climate conditions. Using the 2003 European heat wave and drought as a historical analogue for comparable events in the future, we find that a majority of models underestimate the extremeness of impacts in important sectors such as agriculture, terrestrial ecosystems, and heat-related human mortality, while impacts on water resources and hydropower are overestimated in some river basins; and the spread across models is often large. This has important implications for economic assessments of climate change impacts that rely on these models. It also means that societal risks from future extreme events may be greater than previously thought. © 2019, The Author(s). [less ▲]

Detailed reference viewed: 40 (4 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: 86 (9 ULiège)
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: 95 (8 ULiège)