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International audience; Background and aims: Pioneer plants may improve the ecological restoration of degraded ultramafic areas by plant-soil interaction processes. In this study, we assess the effect of the pioneer actinorhizal tree C. terminale (Casuarinaceae) on the recovery of plant communities and soil functions on degraded tropical ultramafic sites.Methods: Soil and plant samples were collected along a tree-age gradient in two degraded ultramafic sites in Sabah (Northern Borneo, Malaysia): a Technosol and a Leptosol. Chemical composition of plants and soils, and biological activity of soils were assessed at both sites. Plant colonisation was assessed by plot vegetation surveys.Results: An improvement in soil fertility parameters (pH reduction from 8.5 to 6.8, an increase in the concentrations of several nutrients and enhanced soil enzyme activities) was observed along the C. terminale age gradient. However, plant cover and diversity was only improved around mature trees at the site that was not impacted by mining.Conclusion: C. terminale promotes the recovery of several soil functions, mainly related to the storage and recycling of N, P, K, S. Besides plant-soil feedback, other environmental factors (i.e. exposition to sunlight, drought) may play an important role on revegetation of ultramafic soils.

National audience; Phytostabilization of ionic rare earth element mine tailings in South China. Rare earth elements supply: challenges and perspectives

International audience; Surface mining or other disturbing operations on ultramafic outcrops degrade soil conditions and decrease major ecosystem functions in those habitats. Human disturbances exacerbate the harsh conditions of some ultramafic soils, making recovery more difficult. Recovery of ecosystem functions of disturbed areas may vary from passive to active reclamation measures, depending on the starting situation, available resources and expected outcomes. In this study, three treatments (topsoil application, topsoil + non-compacted, and topsoil + non-compacted + organic amendment), representing a gradient of increasing reclamation effort, were tested for the reclamation of a tropical ultramafic Spolic Technosol in Sabah (Malaysia). Soil treatments were tested at the mesocosm-scale for 12 months, and drainage water fluxes, evolution of soil physicochemical parameters, soil microbial activities and spontaneous plant colonisation, diversity and growth were monitored along the duration of the experiment. The results show that application of topsoil improved the plant biomass and water filtration functions in the non-reclaimed sites, with no additional benefit from lesser compaction. The most intensive treatment (topsoil + non-compacted + organic amendment) gave the best improvements in nutrient cycling and biomass production functions, but with a reduction of water filtration function, due to an increase in soluble concentrations and cumulative fluxes of nickel. Introduced species were dominant in the vegetation colonising the mesocosms, and therefore planting of selected native species will be necessary to create habitats for native biodiversity. This information will be useful to select a strategy for the recovery of degraded tropical serpentinite quarries and dump sites.

Requalification des sols d’anciens sites miniers de métaux. Cycle géochimique des métaux

International audience; Rare Earth Elements (REEs) have become essential components of many high-tech products. Among the various known REEs deposits, the ion-adsorption ones, only found in Southern China, represented around 30% of the worldwide production in 2017. Reclamation of the resulting mine tailings is limited by theirpoor physical conditions, their low organic matter and nutrient levels as well as their relatively high residual REEs content.Reclamation practicesof such sites caninclude natural attenuationor phytoremediation, usingsoil amendment or construction, and planting of tolerant speciesor economic crops. These practices induce drastic changes in the biogeochemical conditions of the soils and thus potentially modify REEs and nutrients availability, impacting the sustainability of the reclamation.To gain understanding on the impactof reclamation practiceson REEs dynamics, we studya minetailing in Ganzhou city, Jiangxi province, that has been abandoned for 10y. Phytoremediation techniques are currently tested on the tailings material in experimental plots (2x2m) in which plants and soil development are monitored over time. More specifically, the techniques includephytostabilization using perennial grasses or fiber plants, and phytoextraction using REEs hyperaccumulators. Anobjective of thisstudy is to develop a geochemical model to be able to evaluate the various practices. A process-based multi-surface model has been parameterized for REEs in soils and sedimentsin the platform ORCHESTRA.Based on measured contents of REEs, clays and Al/Fe-(hydr)oxides and solution pH and DOC concentration, we predicted dissolved REEs concentrations in pore water and CaCl2-extract. The model is evaluated by comparing modelled vs.measured REEs solid:solution partitioning. Once validated, such a model could be used to gain more detailed insights on the impact of organic exudate or amendment rates on reclamation sustainability.

International audience; Short-term variations of soil conditions affect the form, mobility and bioavailability of metal pollutants. Released metals migrate toward depth where they are intercepted or precipitate, leading to variable spatial metal distribution patterns, at a macro-, meso- and microscale. Studies at a mesoscale give access to trace metal (TM) associations induced by pedological processes. Although scarcely documented, such meso-scale studies represent an essential step for relevant environmental risk assessment, halfway between field- and molecular-scale investigations. We argued for such approach by performing optical microscopy and micro-X-ray fluorescence on thin sections from two soils, contaminated either by industrial zinc-smelter waste or by urban wastewater. Consistent correlation between key indicators of pedological processes (Fe, Mn, and Ca) and trace metals (Zn, Pb, and Cu) on some 20 elemental maps of TM-hosting soil constituents and pedofeatures reveal distinct coinciding localizations, illustrating TM-accumulation via interception or (co)-precipitation processes. Micromorphological interpretation of characteristic pedofeatures in subsurface horizons (crystals, argillans, ferrans, and mangans) containing significant amounts of TM provide valuable insight into the contaminant dynamics in terms of lixiviation, colloidal transport, redox conditions, or fungal activity. Our mesoscale approach stresses the importance of pedology-based sampling strategies, instead of systematic soil-depth sampling, for soil contamination research in natural ecosystems

International audience; Highlights • Lysimetric monitoring of the water budget of a range of soils, including Technosols • Different hydrodynamics were visible as a function of both soils and time. • Temporal dynamics of water budget followed the seasonal climatic variations. • The most anthropised soils exhibited a decrease of their total water storage capacity. Soil poral architecture controls soil functioning and is submitted to temporal changes. The monitoring of soil structure dynamics is complicated by inherent technical constraints in its measurement that are either punctual or complex. In this study, four soils, from a natural one to incrementally anthropized (including three Technosols: Spolic Toxic, Terric Transportic, Spolic Garbic Hydric), have been studied. Seven 2-m3 lysimetric columns have been setup to compare planted and non-planted treatments over 3 to 6 years. Data on the water balance and the hydrodynamics were continuously acquired. Differences were observed between the various soils as a function of their texture. The presence of vegetation also led to significant differences, especially in hot periods, between the vegetated and the bare soils treatments: the amount of water stored into the soil was up to 210 L m− 2 higher for bare soil. Furthermore, the analysis of the “critical water storage capacity” highlighted differences in the hydrodynamics at two time scales. For vegetated soils, similar seasonal variations depending on the climatic conditions were observed for all soils, with higher SCRIT values in cold periods compared to hot periods (differences were up to 190 L m− 2). These results were attributed to roots development over the climatic year that decreases water storage capacity and increases preferential flows. Besides, significant trend evolution was also observed but only for the youngest i.e. the most anthropized soils. Their total water storage capacity decreased down to 52%. It is possibly due to soil compaction, the increase of pore connectivity related to root development and the formation of organo-mineral associations. Our work promotes the association of monitored lysimeters as tool and the study of soils within a gradient of anthropization in order to describe a pedogenetic process like the dynamics of soil porosity.

Pedogenic processes in soils of urban, industrial, traffic, mining and military areas

International audience; It is now certain that soil evolution will be strongly influenced by climate change. In particular, young soils, such as anthropogenic soils, show evolution patterns that change faster than natural soils. They can contain large quantities of organic pollutants (in the context of industrial activities) which mobility in the environment might differ under the impact of several environmental factors, particularly climate. To better quantify the link between climatic fluctuations and their impact on soil properties, it is important to understand how meteorological records can be derived into pedoclimates. Using HYDRUS-1D, we converted fluctuations of water content and temperature into pedoclimatic events over time as a function of climatic conditions, soil properties and depth. First, using data collected from lysimeters and a local weather station, we calibrated the fluctuations in soil water content and soil temperature. The model efficiently predicts the evolution of soil temperature (index of agreement >0.97 and RMSE

Technosol construction with by-products and wastes: pedogenesis and modelling. SUMMER SCHOOL ON CONTAMINATED SEDIMENTS: CHARACTERIZATION AND REMEDIATION

summary A comprehensive description of water flow in environmental and agricultural systems requires an account of both surface and subsurface pathways. We present a new model which combines a 1D overland flow model and the 2D subsurface flow HYDRUS-2D model, and uses the multi-objective global search method AMALGAM for inverse parameter estimation. Furthermore, we present data from bench-scale flow experiments which were conducted with two 5-m long replicate soil channels. While rainfall was applied, surface runoff was recorded at the downstream end of the soil channel, subsurface drainage waters were sampled at three positions equally spaced along the channels, and pressure heads were recorded at five depths. The experimental observations were used to evaluate the performance of our modeling system. The complexity of the modeling approach was increased in three steps. First, only runoff and total drainage were simulated, then drainage flows from individual compartments were additionally evaluated, and finally a surface crust and immobile soil water were also considered. The results showed that a good match between measured and observed surface runoff and total drainage does not guarantee accurate representation of the flow process. An inspection of the Pareto results of different multiobjective calibration runs revealed a significant trade-off between individual objectives, showing that no single solution existed to match spatial variability in the flow. In spite of the observed crust formation, its consideration in the more complex model structure did not significantly improve the fit between the model and measurements. Accounting for immobile water regions only slightly improved the fit for one of the two replicate soil channels. Discrepancies between relatively complex model simulations and seemingly simple soil channel experiments suggest the presence of additional unknowns, such as heterogeneity of the soil hydraulic properties. Nevertheless, with its versatile subsurface options and powerful inverse method, the model system shows promise for studying hillslope flow problems involving both surface runoff and subsurface flow.

Restoring belts of perennial vegetation in landscapes is widely recognized as a measure of improving landscape function. While there have been many studies of the transport of pollutants through grass filter strips, few have addressed sediment related processes through restored tree belts. In order to identify these processes and quantify their relative contribution to sediment trapping, a series of rainfall simulations was conducted on a 600 m2 hillslope comprising a pasture upslope of a 15 year old tree belt. Although the simulated events were extreme (average recurrence intervals ∼10 and 50 yr), the trapping efficiency of the tree belt was very high: at least 94% of the total mass of sediments was captured. All the size fractions were trapped with a minimum Sediment Trapping Ratio (STR) of 91% for the medium-sized fragments. Fractions 182 µm were totally captured (STR = 100%). Through the joint analysis of sediment budgets and soil surface conditions, we identified different trapping processes. The main trapping process is the sedimentation (at least 62% of trapped sediment mass) with deposits in the backwater and as micro-terraces within the tree belt. Modelling results show that the coarsest size fractions above 75 µm are preferentially deposited. Joint infiltration of water and sediments has also been noticed, however, this process alone cannot explain the selective trapping of the finest fractions. We suggest that the finest fractions transported by the overland flow may be trapped by adsorption on the abundant litter present within the tree belt. Copyright © 2008 John Wiley & Sons, Ltd.

Technosols, soils subjected to a strong human influence and containing significant amounts of artefacts, are characteristic of the Anthropocene. In order to better apprehend their growing importance in our current environment, our knowledge of the evolution and fate of these soils must be improved. The aim of this article is to promote pedogenic modelling for Technosols by proposing an appropriate framework. The paper first defines the characteristics of Technosol pedogenesis, and then considers the requirements for its modelling in light of general concepts of pedogenesis, modelling tools and techniques, and 18 selected existing quantitative models. This mixed technical and conceptual analysis allows us to address at once the modelling approach, the choice of processes, the integration of control variables, the time scales, the spatial representation, and the data needed for such a framework. Technosol pedogenesis is characterised by the soils' anthropic creation, a young age, a climate globally favourable for soil evolution, a surprising level of biological activity, and mostly reactive artefacts as parent materials. Pedogenic processes observed in Technosols are similar to those occurring in more natural soils; however, they generally have fast kinetics and occur in unusual assemblages. We propose that the modelling framework for Technosol evolution should be based on the coupling of process-based models of soil functioning processes and accommodate the peculiar properties of technogenic materials. Our work also highlights modelling features needed for pedogenesis in general: development of biological and physical models, selection of a comprehensive energy unit, dual-time scale modelling, and multi-scale representation of the soil profile. We propose (i) an adaptation of existing energy metrics (entropy, exergy, emergy or EEMT), (ii) a dual-time scale approach, our original concept, based on resilience patterns in soil changes, and (iii) the development of an existing spatial representation. Constructed Technosols are a relevant experimental model which supplies reliable data on soil evolution, data which are required for the development of pedogenic models. Technosols are emblematic of the issues we face for the management of the soils of the Anthropocene. The design of a modelling framework for Technosol evolution should therefore bring interesting developments for pedogenic modelling in general.

National audience; L’hydrologie des sols joue un rôle essentiel dans le cycle de l’eau, puisque la pédosphère constitue l’interface entre l’atmosphère, les eaux superficielles et les eaux souterraines. La dynamique de l’eau dans les sols (infiltration, redistribution, drainage, évapotranspiration) est contrôlée par les conditions aux limites du système et par un ensemble de propriétés hydrodynamiques, traduisant l’architecture de ces milieux poreux spécifiques. Le postulat qui est généralement fait est que ces propriétés hydrodynamiques sont caractéristiques de chaque type de sol, mais invariantes dans le temps. Il est pourtant connu que la structure des sols évolue au cours du temps sous l’effet de leur pédogenèse (évolution tendancielle) et des variations saisonnières (évolution supposée cyclique). Ces changements de structure sont induits par les facteurs extérieurs (i.e.climat, végétation, activité biologique) et sont le résultat de la transformation de la phase solide ou de la redistribution des particules. Ils peuvent ainsi se traduire par des modifications du volume poral, de la taille ou encore de la connectivité des pores du sol. L’évolution hydrologique des sols est donc un phénomène complexe, délicat à caractériser et à quantifier. Il a été choisi de baser notre étude sur quatre sols (avec et sans végétation) au sein d’un gradient, du moins anthropisé (sol le plus ancien) au plus anthropisé (sol le plus jeune), dont le suivi hydrodynamique était réalisé grâce à un dispositif de colonne lysimétrique sur la station expérimentale du Groupement d'Intérêt Scientifique sur les Friches Industrielles (GISFI). L’exploitation et l’interprétation des données expérimentales traduisent très clairement un réarrangement saisonnier de l’espace poral sous l’effet du climat - alternances d’humectation-dessiccation - et de la végétation - compaction du sol par les racines puis augmentation de la macroporosité lors de leur sénescence. A ces variations cycliques s’ajoutent, pour les sols les plus jeunes, une décroissance tendancielle qui s’expliquerait d’une part par leur tassement et d’autre part par la formation de nouveaux agrégats sous l’effet de l’activité biologique.Différents modèles à structure linéaire statique ont été développés. Ils ont permis de modéliser de manière très satisfaisante les humidités à trois profondeurs, à partir de variables extérieures. L’examen des paramètres de ces modèles a non seulement permis de mettre en évidence la contribution de la végétation à la modification du fonctionnement hydrodynamique, mais éclaire la cinétique de cette évolution au cours de la saison végétative. Les travaux actuellement en cours visent maintenant à construire un modèle dont les paramètres varieraient de manière cyclique afin de distinguer et quantifier l'effet de l'évolution tendancielle propre à chaque sol.

The aim of this chapter is to give an overview of plant responses to nitrogen (N) deposition by using two dynamic biogeochemical models coupled with a vegetation module: VSD+-VEG and ForSAFE-VEG. The biogeochemical models were first validated on some French forest sites from the ICP-Forests network. A French vegetation table (which is now part of a European database) containing 230 species with their appropriate ecological environmental parameters, was set up. The outputs of each model in terms of plant response to atmospheric nitrogen deposition were compared to measured values for one forest stand. The two models underestimated the occurrence of certain herbs and grasses and overestimated (ForSAFE-VEG) or underestimated (VSD+-VEG) the presence of certain mosses. This allowed us to improve the validation and thus the calibration of some parameters. For the simulated period ForSAFE-VEG indicated some variations in the occurrence of the plant groups, the mosses group showing the highest increase and indicating a high sensitivity to atmospheric N deposition. No significant changes in the occurrence percentage of plant groups were observed by running the VSD+-VEG model, this model being less sensitive than ForSAFE-VEG to simulate tenuous vegetation changes. The observed changes over time in the dominant ground plant groups using ForSAFE-VEG could be related to changes in site environmental conditions, but only the influence of the maximum N deposition was obvious. Further investigations are needed to compare the performance of the two models on other sites, but these tests of the ForSAFE-VEG and VSD+-VEG models showed promise for simulating the link between N deposition and vegetation diversity.

Demande de financement Ademe; Dans le cadre de la convention internationale de Genève sur la pollution atmosphérique transfrontalièreà longue distance, les réductions des émissions de polluants sont négociées en prenant enconsidération les impacts générés par ces contaminants. Plus particulièrement, l’approche retenuepour quantifier la sensibilité des écosystèmes est basée sur le concept de charge critique.Pour améliorer la détermination des charges critiques pour le territoire national, il est aujourd’huinécessaire de disposer d’une carte numérique de la France, à 1/1 000 000, indiquant précisément lacomposition de la couverture végétale. En effet, un tel document, qui fait actuellement défaut, permettranotamment :– d’améliorer la définition des unités écosystémiques sur lesquelles est basée la modélisationspatiale des charges critiques ;– d’intégrer l’effet des pollutions atmosphériques, notamment azotées, sur la biodiversitécommerecommandé par les récents travaux de la convention de Genève ;– de mieux modéliser les dépôts de polluants atmosphériques sous couvert.En septembre 2006, une demande de financement, portée par Anne Probst responsable de la modélisationet de la cartographie des charges critiques en France, a été déposée auprès de l’ADEMEpour constituer une Base de Données Géographiques de la végétation de la France (BDGveg). L’objetde cette base est la cartographie des unités de végétation présentes ainsi que la description de leurcomposition floristique. La réalisation de la BDGveg s’appuie principalement sur la numérisation des64 feuilles à 1/200 000 éditées par le CNRS entre 1949 et 1991 et qui constitue la carte de végétationdu CNRS.L’objectif de ce rapport d’avancement est de présenter les travaux effectués depuis janvier 2006,date du démarrage du projet. Ce projet est prévu en 3 étapes :1. la réalisation de la BDGveg (scan ou numérisation, redressement, géoréférencement, assemblage,synthèse d’une légende, mise à jour de la couverture) ;2. l’amélioration et la validation de la cartographie (légende, correspondances avec les classificationsexistantes, estimation de l’hétérogénéité des unités cartographiques) ;3. une étude prospective pour développer et évaluer une méthodologie d’estimation des variablesécologiques nécessaires au calcul des charges critiques azotées.La première phase du projet, qui constitue l’étape principale et la plus conséquente, est en coursd’achèvement. Une couverture raster « Végétation — État au moment de relevés » a été réalisée parscan des 64 feuilles de la carte de végétation du CNRS. Une première typologie de la végétation aété synthétisée et une légende hiérarchique sur 4 niveaux a été proposée pour classer les différentesunités de végétation présentes sur le territoire national. Une première version d’une couverture vectorielle« Végétation potentielle » a été créée par digitalisation des 64 cartons botaniques de la cartede végétation du CNRS. La méthodologie pour la réalisation d’une couverture « Végétation - État actuel» est en cours d’élaboration. Cette dernière couverture va être générée par croisement entre lacouverture « Végétation potentielle » et la carte numérique d’occupation du sol Corine Land Cover2000.La deuxième phase du projet (Amélioration et validation) est prévue pour le premier semestre2008. La troisième phase, plus prospective n’a pas encore été abordée.

Models used for decision-making in forestry policy, planning and management are not ye t able to produce a simultaneous evaluation of the effect of global climate change and management on the various ecological and productive functions provided by forest ecosystems. This paper gives an overview of models dev eloped for dendrometry , ecophysiology and soil sciences and considers how the concepts used in these three disciplines can be combined to create decision-making tools for forest management. These new tools should (1) be sufficiently comprehensive to provide answers to management issues at the ecosystem scale, (2) distinguish between generic and site-dependent processes and parameters, (3) make it possible to define and simulate a range of innovative management scenarios in an uncertain environment, with increasingly strong constraints and (4) be well documented and referenced to ensure that they will be used and will continue to be used.; Les outils de modélisation au service de la politique, de la planification et de la gestion forestière ne permettent pas encore une évaluation simultanée de l’impact des changements globaux et de la gestion sur les différentes fonctions écologiques et productives assurées par les écosystèmes forestiers. Nous proposons un état des lieux des modèles disponibles dans les différentes disciplines que sont la dendrométrie, l’écophysiologie et les sciences du sol et comment l’intégration des concepts de ces trois disciplines peut permettre d’élaborer les outils nécessaires au gestionnaire. In fine, ces nouveaux outils devront être suffisamment complets pour répondre à des questions à l’échelle de l’écosystème ; distinguer ce qui relève du processus générique de ce qui reste site-dépendant ; permettre de définir puis simuler des scénarios de gestion variés et innovants en environnement incertain, avec des contraintes de plus en plus fortes ; et être documentés et référencés pour garantir leur pérennité et leur utilisation.

The interactions between soil and vegetation (e.g. root exudation, weathering and uptake or root growth, bioturbation and biomass production) are significant in the initial development of terrestrial ecosystems. Quantitative modelling of such interactions is needed to better understand and predict ecosystem evolution, especially in the context of derelict land restoration. However, in the current models of soil evolution, plant feedbacks on soil are still poorly taken into account. Numerous models have already been developed to reproduce individual processes involving soil and plant but they are not able to simulate the whole as a global, interactive, and complex system. Our objective is to propose a general guideline for a global dynamic model by integrating existing sub-models of individual processes. The focus is on soil under human-controlled vegetation as it is an important issue in ecosystem reclamation. The suggested guideline is based on a review of around 20 existing profile-scale quantitative sub-models which reproduce soil-plant processes. The submodels are mainly based on a physical approach with laws of mass conservation but some rely on statistical and energy-conservation laws. At first a global soil-plant evolution model could be devised by integrating existing mass-conservation sub-models. However, adaptations are needed to reproduce interactions between processes as well as soil-plant feedbacks. Statistical and energy-based approaches could be proposed respectively for calibration and as a general metric combining various chemical or physical stresses. We assess our modelling guideline by confronting it to studies on rehabilitated ecosystems, particularly constructed Technosols as they are relevant experimental models.

National audience; L'utilisation de déchets et de sous-produits en construction de sols est une voie nouvelle pour la refonctionnalisation écologique des sols dégradés. La dégradation des sols en milieux urbain se traduit en effet souvent par des pertes de fonctions et, en particulier, une diminution de l'activité biologique et un défaut des sols à être un support fertile pour la végétation. Restaurer un sol dégradé, c'est alors optimiser son biofonctionnement et créer les conditions de l'implantation durable de végétaux avec des objectifs d'intégration paysagère ou de production de biomasse. La reconstitution de sols a jusqu'à présent essentiellement été développée autour de l'utilisation de matériaux terreux et de déchets organiques « nobles » disposés en couches, purs ou en mélanges. Néanmoins, les matériaux terreux ne sont pas toujours disponibles et leurs coûts économique et environnemental peuvent être élevés. Le concept de construction de sols à partir de matériaux technologiques est quant à lui très récent. La présentation de sites « historiques » et de sites expérimentaux pilotes de construction de sol en conditions climatiques réelles démontreront la faisabilité d'une restauration à grande échelle des sols dégradés et les perspectives de refonctionnalisation écoloe,ique durable seront discutées. Des résultats seront présentés sur l'évolution pédogénétique de ces Technosols construits et leur aptitude à remplir de manière pérenne leur fonction de support de végétation. Les résultats présentés prennent appui sur des travaux à objectifs finalisés conduits sur la station expérimentale du Groupement d'Intérêt Scientifique sur les Friches Industrielles (gisfi.fr) en collaboration entre des partenaires institutionnels, industriels et de la recherche.

Dans cet article nous présentons la numérisation de la carte de végétation de la France publiée par le CNRS en 64 feuilles entre 1947 et 1991. Les couvertures géographiques et les tables de données réalisées lors de ce travail ont été regroupées au sein de la Base de Données Géographique de la VÉGétation de la France (BDGveg_FR). Les couvertures principales représentent respectivement les séries de végétation, sous forme de scan géoréférencé, à 1/200 000 et la carte harmonisée de la végétation potentielle, sous format vectoriel, à 1/1 000 000. La carte harmonisée de la végétation potentielle est accompagnée d'une typologie hiérarchique nationale sur six niveaux synthétisée à partir des légendes des 64 feuilles. L'utilisation de la BDGveg_FR est illustrée par plusieurs exemples de caractérisation des facteurs de répartition de la végétation (altitude, géologie, sol et climat) par croisement avec d’autres sources de données géographiques (modèle numérique d'altitude, couvertures vectorielles à 1/1 000 000 des sols et du sous-sol). La BDGveg_FR est complémentaire des bases de données existantes sur la végétation de la France du fait de sa période de réalisation, de ses échelles cartographiques locales et nationales, de son exhaustivité de couverture et de ses informations sur les groupements végétaux. Cette base peut-être utilisée pour analyser l’impact des changements globaux (par exemple climat, pollution atmosphérique) sur les écosystèmes., In this paper we present the digitalisation of the map of the vegetation of France edited by the CNRS in 64 sheets between 1947 and 1991. The geographical covers and the databases built during this work are gathered in a geographical database called “Base de Données Géographique de la VÉGétation de la France” (BDGveg_FR). The main covers show respectively the vegetation succession stages, as a georeferenced scan, at 1/200,000, and the harmonised map of the potential vegetation, in a vector format, at 1/1,000,000. The harmonised map of the potential vegetation is linked with a national 6-level typology synthesised from the keys of the 64 sheets. Possible uses of the BDGveg_FR are shown with some examples on the determination of the factors of vegetation distribution (altitude, geology, soil and climate) by intersecting it with others sources of geographical data (digital elevation model, vector covers at 1/1,000,000 of soil and geology). The BDGveg_FR is actually complementary to the other databases on the vegetation of France presently available thanks to its period of time, its local and national scales, its exhaustive cover and its information on the plant associations. It can be used to assess the impact of global changes (e.g. climate, atmospheric pollution) on ecosystems.

En dépit de nombreux travaux de cartographie de la végétation, il n'existait jusqu’en 2008 aucune carte numérique des formations végétales couvrant le territoire métropolitain français. Ces informations sont indispensables, entre autres, pour comprendre, évaluer et limiter l'impact des changements environnementaux globaux, notamment des dépôts de polluants atmosphériques, sur les milieux naturels et semi-naturels à l’échelle nationale. L'objectif du travail, présenté ici, a consisté à produire une carte numérique de la végétation de la France à 1/1 000 000 en se basant sur des informations cartographiques existantes, et notamment les cartes de la végétation à 1/200 000 produites par le CNRS à l’initiative de Henri Gaussen. La première étape a conduit à numériser les cartes du CNRS: (i) scannage, assemblage et géoréférencement des cartes et des cartons associés; (ii) digitalisation, assemblage et géoréférencement des cartons botaniques, représentant, au 1/1 250 000, la végétation considérée comme potentielle. Une légende hiérarchique, éditée à partir des légendes détaillées de toutes les cartes au 1/200 000, a été synthétisée à l’échelle du territoire national pour renseigner la couverture de la végétation potentielle ainsi produite. Dans un deuxième temps la couverture de la végétation potentielle a été croisée avec des bases de données nationales de relevés floristiques (bases EcoPlant de l’Engref, SOPHY du CNRS et relevés de L’Inventaire Forestier National). Ce croisement, en plus d’être une procédure de validation de la couverture, a permis de renseigner chacune des unités cartographiques de la végétation avec des informations édaphiques (pH, rapport carbone sur azote, taux de saturation en bases, niveau d’engorgement) et floristiques (liste d’espèces caractéristiques et alliances phytosociologiques principales). Dans une troisième étape, l’occupation végétale actuelle a été déduite à partir d’un croisement avec d'autres cartographies numériques nationales récentes (occupation du sol avec Corine Land Cover 2000). Ce nouveau produit numérique à l’échelle nationale a pour but l’élaboration d’une cartographie des écosystèmes et de leur sensibilité vis-à-vis des pollutions atmosphériques acides, azotées et métalliques (« charges critiques »). Il constitue un outil précieux pour la communauté des chercheurs et des enseignants et participe à la sauvegarde d’un patrimoine scientifique. En effet certaines cartes de végétation du CNRS n'étaient plus disponibles qu'en quelques exemplaires papiers.

International audience; We use critical load modelling to assess the risks caused by diffuse Cd and Pb pollution on two sites located on forest and arable lands respectively. The objectives of this work are: (i) to test the proposed critical load method on arable land and, (ii) to compare critical loads with current measured Cd and Pb fluxes. For the two sites, computed critical concentrations of Cd and Pb in soil water regarding the protection of soil organisms (2.3 and 4.9 mg.m-3 respectively for the forest, 0.7 and 4.5 mg.m-3 respectively for the arable site) are above current concentrations. Modelled critical loads (15.6 and 46.4 g.ha-1.a-1 for Cd and Pb respectively) are lower than current inputs for the forested site. However the arable site would be in exceedance with current inputs larger than modelled critical loads (1.3 and 7.1 g.ha-1.a-1 for Cd and Pb respectively). These results are going to be checked thanks to long-term monitoring and ecotoxicological tests.

Owner: SoL Added to JabRef: 2010.03.11Owner: SoL Added to JabRef: 2010.03.11; En dépit de nombreux travaux de cartographie de la végétation, il n'existe, à l'heure actuelle, aucune carte numérique des formations végétales couvrant le territoire métropolitain français. Or cette information est indispensable pour modéliser et limiter l'impact des dépôts de polluants atmosphériques sur les milieux naturels et semi-naturels nationaux. L'objectif du travail, présenté ici, est de produire une carte numérique de la végétation de la France à 1/1 000 000 en se basant sur des informations cartographiques existantes, et notamment les cartes de la végétation à 1/200 000 produites par le CNRS à l’initiative de Henri Gaussen. La première étape a consisté à numériser les cartes du CNRS : (i) scannage, assemblage et géoréférencement des cartes et des cartons associés ; (ii) digitalisation, assemblage et géoréférencement des cartons botaniques, représentant, au 1/1 250 000, la végétation considérée comme potentielle. Une légende hiérarchique a été synthétisée à l’échelle du territoire national pour renseigner la couverture de la végétation potentielle ainsi produite. Dans une deuxième étape, l’occupation végétale actuelle va être déduite à partir d’un croisement avec d'autres cartographies numériques nationales récentes (occupation du sol avec Corine Land Cover, cartes de l’Institut Forestier Nationale pour la gestion et les essences forestières, recensement général agricole). Dans un troisième temps, une validation de la couverture est prévue par confrontation avec de bases de données nationales de relevés de la végétation (bases EcoPlant de l’ENGREF, SOPHY du CNRS et relevés de l’Institut Forestier National). La version 0 de la carte de la végétation potentielle de la France, achevée depuis peu, sera présentée lors de cette communication. Ce nouveau produit numérique à l’échelle nationale servira de base à l’élaboration d’une cartographie de la sensibilité des écosystèmes vis-à-vis des pollutions atmosphériques acides, azotées et métalliques. Il constituera un outil précieux pour la communauté des chercheurs et des enseignants et participera à la sauvegarde d’un patrimoine scientifique. En effet certaines cartes de végétation du CNRS n'étant plus disponibles qu'en quelques exemplaires papiers.

National audience

One of the most important scientific challenges of digital elevation modeling is the development of numerical representations of large areas with a high resolution. Although there have been many studies on the accuracy of interpolation techniques for the generation of digital elevation models (DEMs) in relation to landform types and data quantity or density, there is still a need to evaluate the performance of these techniques on natural landscapes of differing morphologies and over a large range of scales. To perform such an evaluation, we investigated a total of six sites, three in the mountainous region of northern Laos and three in the more gentle landscape of western France, with various surface areas from micro-plots, hillslopes, and catchments. The techniques used for the interpolation of point height data with density values from 4 to 109 points/km(2) include: inverse distance weighting (IDW), ordinary kriging (OK), universal kriging (UK), multiquadratic radial basis function (MRBF), and regularized spline with tension (RST). The study sites exhibited coefficients of variation (CV) of altitude between 12% and 78%, and isotropic to anisotropic spatial structures with strengths from weak (with a nugget/sill ratio of 0.8) to strong (0.01). Irrespective of the spatial scales or the variability and spatial structure of altitude, few differences existed between the interpolation methods if the sampling density was high, although MRBF performed slightly better. However, at lower sampling densities, kriging yielded the best estimations for landscapes with strong spatial structure, low CV and low anisotropy, while RST yielded the best estimations for landscapes with low CV and weak spatial structure. Under conditions of high CV, strong spatial structure and strong anisotropy, IDW performed slightly better than the other method. The prediction errors in height estimation are discussed in relation to the possible interactions with spatial scale, landform types, and data density. These results indicate that the accuracy of interpolation techniques for DEM generation should be tested not only in relation to landform types and data density but also to their applicability to multi-scales. (c) 2006 Elsevier B.V. All rights reserved.

International audience; Aggregate breakdown due to rainfall action causes crusting and interrill erosion. Erodibility is seemingly determined by the capacity of surface aggregates to resist the effects of rainfall. In this paper, we evaluated the relevance of an aggregate stability measurement, which comprises three treatments, in order to characterize aggregate breakdown dynamics. Two cultivated soils were studied: a clay loam slightly sensitive to erosion and a more susceptible silt loam. We compared the size distributions of microaggregates produced by the three aggregate stability treatments with the results from a rainfall simulation. The behaviour of four initial aggregate size classes (< 3 mm, 3–5 mm, 5–10 mm and 10–20 mm) was also compared to study the influence of the initial aggregate size on the nature of resulting aggregates. The mean weight diameter was from 200 to 1400 µm for the silt loam and from 600 to 7000 µm for the clay loam. The two experiments – aggregate stability measurements and aggregate breakdown dynamics under rainfall – yielded similar results. Qualitative analysis showed that for both soils the sizes of fragments produced by breakdown with the aggregate stability tests and under rainfall were similar and seemed to be qualitatively independent of the size of initial aggregates. We first schematized the structural organization of aggregates in cultivated horizons with a simple hierarchical model at two levels: (i) < 250 µm microaggregates and (ii) > 250 µm macroaggregates made by the binding together of microaggregates. We then developed a model of aggregate breakdown dynamics under rainfall which gives, for various rainfall durations, the size distributions of resulting fragments on the basis of aggregate stability measurements. We obtained a correlation coefficient, r, of 0.87 for the silt loam and of 0.91 for the clay loam, showing that the experimental and predicted mass percentages were linearly related for each size fraction.

International audience; Splash is an essential process in interrill erosion because it detaches soil fragments from their substrate and transports them. However, splash measurements are difficult to interpret and relatively little is known about the influence of particle characteristics on the spatial distribution of splash. The objective of this work is to study the splash distribution of different size fractions for aggregated soils. We used a recently proposed theory for spatial distribution by splash to interpret experimental data on the radial distribution of soil fragments splashed by simulated rainfall. A laboratory device with five concentric rings was used to determine average splash lengths for 16 fragment size fractions (0.05 to >2000 µm) of four soils. Sieved soil (3- to 5-mm size fraction) was exposed to simulated rainfall at 29 mm h–1 and with a time-specific kinetic energy of 252 J m–2 h–1. We interpreted the measured masses of fragments splashed into the different rings using an approximate solution of the exponential splash distribution theory applied to the experimental design. We demonstrated that the theory is valid for bulk aggregated soil as well as for individual fragment size fractions. The derived average splash lengths ranged from 4 to 23 cm, depending on the fragment size and soil. Splash lengths were greatest for soil fragments of 100 to 200 µm, and decreased for finer and coarser size fractions. Comparison of these findings with physically-based theory suggests that the coarser fragments, 50 to 2000 µm, are transported as single airborne particles, whereas the smaller ones

41 ref. doi:10.1016/j.envpol.2003.12.023; International audience; Metal distribution patterns in superficial soil horizons of agricultural land affected by metallurgical point-source pollution were studied using optical and electron microscopy, synchrotron radiation and spectroscopy analyses. The site is located in northern France, at the center of a former entry lane to a bunker of World War II, temporarily paved with coarse industrial waste fragments and removed at the end of the war. Thin sections made from undisturbed soil samples from A and B horizons were studied. Optical microscopy revealed the occurrence of yellow micrometer-sized (Ap horizon) and red decamicrometer-sized spherulites (AB, B1g horizons) as well as distinct distribution patterns. The chemical composition of the spherulites was dominated by Fe, Mn, Zn, Pb, Ca, and P. Comparison of calculated Zn stocks, both in the groundmass and in spherulites, showed a quasi-exclusive Zn accumulation in these neoformed features. Their formation was related to several factors: (i) liberation of metal elements due to weathering of waste products, (ii) Ca and P supply from fertilizing practices, (iii) co-precipitation of metal elements and Ca and P in a porous soil environment, after slow exudation of a supersaturated soil solution in more confined mineral media.

Aggregate stability is a soil characteristic often linked with soil erodibility, but this relationship is generally empirical. The aggregate size distribution is a recognized factor influencing crust characteristics and transport during interrill erosion events. This parameter was used in this work in order to improve the understanding of the relationship between aggregate stability and erodibility. A second aspect of this study was to investigate the size selectivity of interrill erosion processes, i.e. breakdown, detachment by splash and transport by overland flow. This experimental work was based on rainfall simulations and aggregate stability tests which were performed using two different soils: a clay loam slightly sensitive to erosion, and a more susceptible silt loam. Size distributions of soil fragments either produced by aggregate stability tests or detached by splash or transported by runoff were measured by both wet sieving and laser diffraction sizer analysis. The clay loam is particularly stable and has coarse breakdown products with mean weight diameters larger than 1400 µm. Aggregate breakdown is more efficient for the silt loam and leads to finer soil fragments with mean weight diameters between 229 and 380 mm. For the more stable soil, the clay loam, splash rate and sediment concentration are respectively two and six times lower and less time variable than for the silt loam. For the two soils, detachment by splash and short distance transport are size-selective interrill erosion processes. This selectivity leads to the enrichment of silt and clay fractions of the eroded aggregates in comparison with the breakdown products. The low erodibility of the more stable soil is in accordance with results of aggregate stability tests. Copyright © 2004 John Wiley & Sons, Ltd.

Models used for decision-making in forestry policy, planning and management are not yet able to produce a simultaneous evaluation of the effect of global climate change and management on the various ecological and productive functions provided by forest ecosystems. This paper gives an overview of models developed for dendrometry, ecophysiology and soil sciences and considers how the concepts used in these three disciplines can be combined to create decision-making tools for forest management. These new tools should (i) be sufficiently comprehensive to provide answers to management issues at the ecosystem scale, (ii) distinguish between generic and site- dependent processes and parameters, (iii) make it possible to define and simulate a range of innovative management scenarios in an uncertain environment, with increasingly strong constraints and (iv) be well documented and referenced to ensure that they will be used and will continue to be used.

Reduction of air pollutant emissions are negotiated under the Geneva convention on long-range transboundary air pollution. These international negotiations are based on the effects of atmospheric contaminants. To quantify the effects on the ecosystems, the critical loads concept is used. A critical load geographical database (or BDGCC) was created in 1997 to manage the environmental data (soil, parent material, hydrology, vegetation, ecosystems) needed to spatially model the critical loads over the French territory. Since then the structure of the BDGCC has been regularly updated to take into account new applications (in particular geographic information system) and needs in model input parameters. With this tool, updated maps of critical loads have been regularly produced for different air pollutants. In this report, we are presenting the last works done around the BDGCC. A geographical database for the French vegetation is in progress. Based on those data as well as on the geo-pedological map made previously, a new ecosystem map is currently under construction for France. The ecosystem correponds to the modelling unit for critical loads. A finer spatial resolution as well as more detailled attributary data were needed to represent those modelling units. New results have also been obtained on the modelling of eutrophication by nitrogen. A new map of critical load for nutrient nitrogen have been produced with the empirical method. We are currently developping a new method to model the effects of nitrogen deposition on biodiversity. Some new results are also available for the modelling of metal critical loads. New data, needed to improve existind models, have been obtained. A new model for agricultural area has been developed and tested. ix; Dans le cadre de la convention internationale de Genève sur pollution atmosphérique transfrontalière à longue distance, les réductions des émissions de polluants sont négociées en prenant en considération les impacts générés par ces contaminants. L’approche suivie pour quantifier l’impact sur les écosystèmes est basée sur le concept de charge critique. Afin de gérer l’ensemble des informations environnementales (sols, matériaux parentaux, hydrologie, végétation, écosystèmes) nécessaires à la modélisation spatiale des charges critiques en polluants atmosphériques sur le territoire français métropolitain, une Base de Données Géographiques Charges Critiques (BDGCC) a été créée en 1997. La structure de la BDGCC a été régulièrement améliorée depuis afin de prendre en compte les évolutions technologiques (système d’information géographique notamment) et les nouveaux besoins en terme de données d’entrée des modèles. Cet outil a permis de fournir régulièrement des cartes de charges critiques mises à jour pour différents polluants atmosphériques. Dans ce rapport, sont présentés les derniers travaux, réalisés ou en cours, autour de la BDGCC. Plusieurs chantiers importants ont été ouverts. Tout d’abord la réalisation d’une base de données géographiques de la végétation de la France qui permettra d’avoir des informations plus détaillées sur la végétation métropolitaine. À partir de ces données de végétation et de la carte géo-pédologique de la France réalisée auparavant, une nouvelle cartographie des écosystèmes de France est en cours de développement. Les écosystèmes sont l’unité de base des modèles de charges critiques et des informations plus détaillées, à la fois en terme de résolution spatiale et de données descriptives, étaient indispensables. Un autre axe de travail est la modélisation des charges critiques en azote eutrophisant. Une nouvelle carte des charges critiques eutrophisantes a été réalisée selon la méthode empirique. La mise au point d’un modèle qui permettrait de prendre en compte l’impact des dépôts azotés sur la biodiversité a commencé à être abordé. Le dernier point concerne la modélisation des charges critiques métalliques. Différents travaux ont été menés pour améliorer les modèles existants et définir une stratégie de modélisation pour les agrosystèmes.

With the need for better management of natural resources and development of sustainable cities, urban soils are becoming an object of primary interest. Indeed, they fulfill a large set of functions, and provide several ecosystem services.[br/]Soils of areas where human activity exerts a high pressure are called SUITMAs (Soils in Urban, Industrial, Traffic, Mining and Military areas). Most SUITMAs are intensively managed and highly disturbed, but some exhibit properties close to natural soils. Their capacity to provide ecosystem services varies greatly according to their characteristics.Knowledge of the properties, functions of SUITMAs and the provided ecosystem services is required, and studies can use the classical tools of soil science.; Avec le besoin d'une meilleure gestion des ressources naturelles et le développement des villes durables, les sols urbains sont devenus un objet de grand intérêt. Ils remplissent un grand nombre de fonctions et fournissent une large gamme de services écosystémiques.[br/]Les sols des zones où l'activité humaine exerce une pression élevée sont appelés SUITMAs (Soils in Urban, Industrial, Traffic, Mining and Military areas). Une majorité de ces SUITMAs est très perturbée, même si certains présentent des propriétés proches de celles des sols naturels. Leur capacité à fournir des services écosystémiques varie en fonction de leurs caractéristiques.[br/]Les besoins de connaissances sont importants sur les propriétés, les fonctions des SUITMAs et les services écosystémiques qu’ils rendent, et les outils classiques de la science du sol s’avèrent pertinents pour leur étude.

[début du texte] L'Anthropocène est une époque qui se caractérise à la fois par la forte pression que les activités humaines exercent sur les sols mais, également, par les attentes de plus en plus marquées de la société vis-à-vis de ces milieux. Dans ce cadre, la modélisation quantitative de la pédogenèse est un outil qui reste à développer pour mieux relever les défis de cette nouvelle ère et évaluer l'évolution future des sols ainsi que des services écosystémiques associés.

International audience; In the current Anthropocene, in which human activities have become the major driving force affecting the environment, Soils of Urban, Industrial, Traffic, Mining, and military Areas (SUITMAs) are spreading. If we consider urban expansion as a proxy of these areas, up to 3% of the world land surface is already covered by SUITMAs and this percentage is growing. SUITMAs are often considered as degraded soils however they provide a wide range of ecosystem services (ES), including provisioning, regulating, and cultural services. To design and explore sustainable, and consistent scenarios for land-use planning including operations like brownfield rehabilitation or the development of urban green areas, there is a need to asses the various ES that are supported by SUITMAs. Whereas still under-developed, soil models adapted to SUITMAs are a basis to quantify and predict ES at the territory scale. Thus the objective of this communication is to review the state of development in the modeling of soil processes that support ES in SUITMAs. Our work is based on two recently published position papers (Morel et al., 2015, Ecosystem services provided by soils of urban, industrial, traffic, mining, and military areas (SUITMAs), Journal of Soils and Sediments and Leguédois et al., 2016, Modelling pedogenesis of Technosols, Geoderma). This mixed technical and conceptual analysis, including a detailed review of a corpus of existing models, allows us to address at once the features of a modeling framework for SUITMAs: the modeling approach, the identification of relevant soil processes, the time scales, and the spatial representation. Concerning the modeling approach, our work highlights that a SUITMAs' framework can be based on: (i) the process-based approach already well developed for others soils; (ii) the coupling of the numerous existing models, this coupling being facilitated by the use of techniques like modeling platforms, uncertainty and sensitivity analyses, or Bayesian methods. According to our work, the most crucial processes needed to represent ES in SUITMAs are related to structure dynamic (aggregation and porosity evolution, compaction), microbial activity, water transfer, and evolution of anthropic or natural organic matters. Whereas water transfer is globally well modeled, developments are necessary for the others processes. As soil processes like organic matter degradation or water transfer are highly seasonal, the models designed for ES assessment have to perform at the annual scale. Longer-term changes have also to be integrated at a decade scale as this timing is consistent with land-use planning. However, models at the decade scale are lacking. Soil's process-based models are mainly dealing with the profile scale and the developments for SUITMAs are focused on this scale but integration at a larger scale is needed to consider ES assessment at the territory level. Along with identified developments in SUITMAs' modelling, the global quantification and prediction of ES need to integrate, among others, economical and social dimensions. To do so, soil models could either by used in a companion approach or coupled in interdisciplinary global models.

Reduction of air pollutant emissions are negotiated under the Geneva convention on long-range transboundary air pollution. These international negotiations are based on the effects of atmospheric contaminants. To quantify the effects on the ecosystems, the critical loads concept is used. A critical load geographical database (or BDGCC) was created in 1997 to manage the environmental data (soil, parent material, hydrology, vegetation, ecosystems) needed to spatially model the critical loads over the French territory. Since then, the structure and the content of the BDGCC have been regularly updated and increased in order to take into account new applications (in particular geographic information system) and needs in model input parameters. With this tool, updated maps of critical loads have been regularly produced for different air pollutants. In this report, we are presenting the last works done around the BDGCC. A geographical database for the French vegetation has been achieved. Based on those data as well as on the geo-pedological map made previously, a new ecosystem map is currently under construction for France. Works are also going on the modelling of eutrophication by nitrogen with the preliminary developments of models which integrate the effects of nitrogen deposition on biodiversity. Some new results are also available for the modelling of metal critical loads. New data, needed to improve existing models, have been obtained.; Dans le cadre de la convention internationale de Genève sur pollution atmosphérique transfrontalière à longue distance, les réductions des émissions de polluants sont négociées en prenant en considération les impacts générés par ces contaminants. L’approche suivie pour quantifier l’impact sur les écosystèmes est basée sur le concept de charge critique. Afin de gérer l’ensemble des informations environnementales (sols, matériaux parentaux, hydrologie, végétation, écosystèmes) nécessaires à la modélisation spatiale des charges critiques en polluants atmosphériques sur le territoire français métropolitain, une Base de Données Géographiques Charges Critiques (BDGCC) a été créée en 1997. La structure de et le contenu la BDGCC ont été régulièrement amélioré et augmenté depuis, afin de prendre en compte les évolutions technologiques (système d’information géographique notamment) et les nouveaux besoins en terme de données d’entrée des modèles. Cet outil a permis de fournir régulièrement des cartes de charges critiques mises à jour pour différents polluants atmosphériques. Dans ce rapport, sont présentés les derniers travaux, réalisés ou en cours, autour de la BDGCC. Plusieurs chantiers importants ont été ouverts. Tout d’abord la réalisation d’une base de données géographiques de la végétation de la France qui permet d’avoir des informations plus détaillées sur la végétation métropolitaine. À partir de ces données de végétation et de la carte géo-pédologique de la France réalisée auparavant, une nouvelle cartographie des écosystèmes de France est en cours de développement. Un autre axe de travail est la modélisation des charges critiques en azote eutrophisant avec notamment des travaux préliminaires pour l’utilisation de modèles qui prennent en compte l’impact des dépôts azotés sur la biodiversité. Le dernier point concerne la modélisation des charges critiques métalliques. Différents travaux ont été menés pour améliorer les modèles existants et acquérir des données plus précises sur la dynamique des éléments traces métalliques (ETM) dans les écosystèmes.

Date du contrat: 14/12/2006; Within the international convention of Geneva on long distance transboundary air pollution, the negotiation for the reduction of pollutants emission is impactoriented. The general approach to quantify the sensitivity of ecosystems to air pollutants is based on the concept of critical loads. To enhance the assessment of critical loads for eutrophying nitrogen at the national scale, there is a need of a detailed vegetation map with information on plant species composition. Such a map would enable: - to take into account impacts of air pollutants, particularly nitrogen, on biodiversity, as suggested by the most recent xi works of the convention, - to enhance the description of the spatial modelling units used at the national scale for critical load modelling, - to better characterise throughfall atmospheric deposition and nitrogen export by the biomass. In September 2006, Anne Probst, in charge of the modelling and the mapping of critical loads for France, applied to the French environmental agency (Ademe) for funds in order to realise a digital geographic database of the vegetation of France (BDGveg). The purposes of this database are the mapping of the French vegetation units and the description of their species composition. The BDGveg was based mainly based on the digitising of the vegetationmap of the CNRS. Thismap is composed of the 64 paper maps produced by the French centre for scientific research (CNRS) between 1947 and 1991. The objective of the final report is to present: – the material and the methods used to produce the BDGveg, – the characteristics of the produced items, – the perspectives for future works. All the items planed in the application for funds have beenmade: – a coherent nation wide hierarchical legend based on the vegetation map of the CNRS and validated by experts; – a raster coverage representing the vegetation at the time of the survey (1/200 000) resulting from the scan of the paper maps; – a vector coverage representing the potential vegetation at 1/1 250 000; this coverage has been checked by comparison with floristic databases (IFN and EcoPlant-Sophy); – some methodological lookouts for the development of biodiversity-targeted critical load models. Additional items have been produced during the course of this project: – a database compiling the information on the authors of the vegetation map of the CNRS; – extra layers at raster (sol nutrient status, soil use, agriculture, rainfall, agricultural risks) and vector format (secondary tree species, distribution of Mediterranean species, drainage levels); – the first draft version of a coverage representing the vegetation at the year 2000 with themethodology to realise a final version. xii; Dans le cadre de la convention internationale de Genève sur la pollution atmosphérique transfrontalière à longue distance, les réductions des émissions de polluants sont négociées en prenant en considération les impacts générés par ces contaminants. Plus particulièrement, l’approche retenue pour quantifier la sensibilité des écosystèmes est basée sur le concept de charge critique. Pour améliorer la détermination des charges critiques en azote eutrophisant pour le territoire national, il est aujourd’hui nécessaire de disposer d’une carte numérique de la France indiquant précisément la composition de la couverture végétale. En effet, un tel document, qui fait actuellement défaut, permettra notamment : – d’intégrer l’effet des pollutions atmosphériques, notamment azotées, sur la biodiversité comme recommandé par les récents travaux de la convention de Genève ; – d’améliorer la définition des unités écosystémiques sur lesquelles est basée la modélisation spatiale des charges critiques ; – de mieux modéliser les dépôts de polluants atmosphériques sous couvert et l’exportation d’azote par la biomasse. En septembre 2006, une demande de financement, portée par Anne PROBST responsable de la modélisation et de la cartographie des charges critiques en France, a été déposée auprès de l’Ademe pour constituer une Base de Données Géographiques de la VÉGétation de la France (BDGveg). L’objet de cette base est la cartographie des unités de végétation présentes ainsi que la description de leur composition floristique. La réalisation de la BDGveg s’appuie principalement sur la numérisation des 64 feuilles éditées par le CNRS entre 1947 et 1991 et qui constitue la carte de végétation du CNRS. L’objectif de ce rapport final est de présenter l’ensemble des travaux réalisés depuis janvier 2006, date du démarrage du projet. Dans le détail, il expose : – les sources et les méthodologies employées pour réaliser la BDGveg, – les caractéristiques des délivrables produits, – les perspectives de travail et de valorisation. L’ensemble des délivrables planifiés dans la demande de financement ont été réalisés : – une typologie hiérarchique de la végétation de la France basée sur la carte de végétation du CNRS et validée par expertise ; – une couverture géographique matricielle de la végétation au moment de l’établissement de la carte de végétation du CNRS au 1/200 000 (scan des cartes de la végétation) ; – une couverture géographique vectorielle de la végétation potentielle de la France à 1/1 250 000 vérifiée à l’aide des bases de données floristiques EcoPlant- Sophy et IFN ; – des perspectives méthodologiques pour le développement des modèles de charges critiques en azote eutrophisant qui prennent en compte l’impact sur la biodiversité végétale. Par ailleurs, quelques délivrables supplémentaires ont également été produits dans le cadre de ce projet : – une base de données des auteurs et des réalisateurs de la carte de végétation du CNRS; – des couvertures géographiques secondaires matricielles (édaphologie, utilisation du sol, agriculture, pluviométrie, adversité agricole) et vectorielles (essences forestières secondaires, aire des espèces méditerranéennes, niveau de drainage) ; – une première version intermédiaire d’une couverture « Végétation—État 2000 » avec la mise au point d’une procédure de généralisation pour produire une couverture finalisée. L’ensemble des couvertures géographiques numériques, ainsi que la base de données « typologie », ont été regroupées dans la BDGveg.