Fine scale spatialised prospective modelling - a methodological approach. Application to water management in Brittany

International audienceThe main objective of this work is to elaborate a generic methodological approach to build prospective scenarios spatially explicit at a local scale. This approach is based on the scenario method used in prospective studies, and uses methodological techniques developed for the modelling of complex systems. The scenario-development process comprises four steps: construction of the basis, scenario building, giving a spatial dimension to the scenarios, and their evaluation. Applied in the framework of water planning in the Brittany region and more precisely of the application of the Water Planning and Management Schemes (WPMS) on the Blavet watershed, the approach is illustrated here by the example of one explanatory scenario and one normative scenario, both aiming at evaluating the potential impact of the 2006 Common Agricultural Policy and farms enlargement on futures land uses

Approche systémique du fonctionnement d'un territoire agricole bocager

International audienceCet article présente une approche systémique du fonctionnement de territoires bocagers porteurs d'enjeux environnementaux. Après l'étude des dynamiques spatiotemporelles passées et actuelles des paysages, l'identification et la hiérarchisation des facteurs explicatifs des changements observés, cette approche met en évidence les échelles auxquelles ils se produisent et les différents acteurs qui interviennent dans l'évolution de ces paysages. Cette approche illustre la complexité des changements d'usage des sols dans des paysages très fragmentés en région agricole intensive. Elle constitue un préalable à la simulation de changements futurs et à l'élaboration de politiques de gestion durable

本館無線網路認證系統異動

Ecological studies need accurate environmental data such as vegetation characterization, landscape structure and organization, to predict and explain the spatial distribution of biodiversity. Few ecological studies use remote sensing data to assess the biophysical or structural properties of vegetation to understand species distribution. To date, synthetic aperture radar (SAR) data have seldom been used for ecological applications. However, these sensors provide data allowing access to the inner structure of vegetation which is a key information in ecology. The objective of this article is to compare the predictive power of ecological habitat structure variables derived from a TerraSAR-X image, an aerial photograph and a SPOT-5 image for species distribution. The test was run with a hedgerow network in Brittany and assessed the spatial distribution of the forest ground carabid beetles which inhabit these hedgerows. The results confirmed that radar and optical images can be indifferently used to extract hedgerow network and derived landscape metrics (hedgerow density, network grain) useful to explain the spatial distribution of forest carabid beetles. In comparison with passive optical remotely sensed data, VHSR SAR images provide new data to characterize vegetation structure and more particularly hedgerow canopy cover, a variable known to explain the spatial distribution of carabid beetles in an agricultural landscape, but not yet quantified at a fine scale. The hedgerow canopy cover derived from the SAR image is a strong predictor of the abundance of forest carabid beetles at two scales i.e., a local scale and a landscape scale

Cartographie des grands types de végétation par télédétection : étude de faisabilité (Bretagne, Basse-Normandie et Pays-de-la-Loire)

annexes sur demanderapport de rechercheL'objectif de cette étude est d'évaluer les potentialités qu'offrent l'imagerie aérienne et satellitaire à haute et très haute résolution spatiale pour la cartographie des grands types de végétation des régions Bretagne, Basse-Normandie et Pays de la Loire. Pour ce faire, différents types d'images (BDORTHO® IRC, SPOT5, Worldview-2) ont été acquises sur quatre sites représentatifs de la diversité des végétations présentes sur ce territoire. Des procédures de classification ont été établies et leur reproductibilité à d'autres sites a été vérifiée. La typologie des végétations utilisée est celle proposée par le Conservatoire Botanique National de Brest (CBN de Brest) qui articule par une démarche " bottom-up ", la typologie phytosociologique utilisée sur le terrain, avec une typologie physionomique (structurale) pouvant être " comprise " par une approche télédétection. L'approche orientée-objet non supervisée a été privilégiée pour ce projet. Seules les procédures de classification des images Worldview-2 (démarche plus exploratoire) combinent l'approche orientée-objet non supervisée à la méthode pixel supervisée. Les performances globales des procédures pour chaque image sont calculées par l'intermédiaire d'un indice kappa pour les niveaux " occupation du sol ", " grands types de végétations " et " types de formations végétales ". Les résultats les plus concluants sont obtenus, pour la plupart des végétations étudiées, à partir de l'image Worldview-2, puis la BDORTHO® IRC et enfin les images SPOT5. L'identification de certaines végétations donne des résultats médiocres ; des recommandations sont proposées pour les améliorer

Upscaling nitrogen removal capacity from local hotspots to low stream orders’ drainage basins

International audienceDenitrification is the main process removing nitrate in river drainage basins and buffer input from agricultural land and limits aquatic ecosystem pollution. However, the identification of denitrification hotspots (for example, riparian zones), their role in a landscape context and the evolution oftheir overall removal capacity at the drainage basin scale are still challenging. The main approaches used (that is, mass balance method, denitrification proxies, and potential wetted areas) suffer from methodological drawbacks. We review these approaches and the key frameworks that have been proposed to date to formalize the understanding of the mechanisms driving denitrification: (i) Diffusion versus advection pathways of nitrate transfer, (ii) the biogeochemical hotspot, and (iii) the Damköhler ratio. Based on these frameworks, we propose to use high-resolution mapping of catchment topography and landscape pattern to define both potential denitrification sites and the dynamic hydrologic modeling at a similar spatial scale (<10 km2). It would allow the quantification of cumulative denitrification activity at the small catchment scale, using spatially distributed Damköhler and Peclet numbers and biogeochemical proxies. Integration of existing frameworks with new tools and methods offers the potential for significant breakthroughs in the quantification and modeling of denitrification in small drainage basins. This can provide a basis for improved protection and restoration of surface water and groundwater quality

Exploring subtle land use and land cover changes: a framework for future landscape studies

UMR AMAP, équipe 3International audienceLand cover and land use changes can have a wide variety of ecological effects, including significant impacts on soils and water quality. In rural areas, even subtle changes in farming practices can affect landscape features and functions, and consequently the environment. Fine-scale analyses have to be performed to better understand the land cover change processes. At the same time, models of land cover change have to be developed in order to anticipate where changes are more likely to occur next. Such predictive information is essential to propose and implement sustainable and efficient environmental policies. Future landscape studies can provide a framework to forecast how land use and land cover changes is likely to react differently to subtle changes. This paper proposes a four step framework to forecast landscape futures at fine scales by coupling scenarios and landscape modelling approaches. This methodology has been tested on two contrasting agricultural landscapes located in the United States and France, to identify possible landscape changes based on forecasting and backcasting agriculture intensification scenarios. Both examples demonstrate that relatively subtle land cover and land use changes can have a large impact on future landscapes. Results highlight how such subtle changes have to be considered in term of quantity, location, and frequency of land use and land cover to appropriately assess environmental impacts on water pollution (France) and soil erosion (US). The results highlight opportunities for improvements in landscape modelling

Wetlands

Scientists predict that the environment over the next 100 years will be threatened by severe challenges--the loss of biodiversity, expected changes in world-wide climate, and decreasing amounts of arable land and potable water for an exploding human population. All of these will greatly impact how the earth will be able to support life in the future. And at the center of these global environmental changes are developments in land use. Over the last 300 years, and in particular the last 50 years, the earth's land has been altered drastically as a result of increasing industrialization and urbanization worldwide, as well as by changes in agricultural techniques in lands under cultivation. These developments raise troubling questions about out future: How will these changes affect the sustainability of certain types of land use? How will they impinge upon critical regions, like rainforests and deserts? Will the earth be able to provide for the basic human needs of food, shelter, and water? The Earth's Changing Land: An Encyclopedia of Land Use and Land-Cover Change is an A-to-Z encyclopedia that addresses all aspects of the science of land-use change: Evidence of land-use and land-cover change over the last 300 years, and how these changes impact the lives of people today Discussions of the models and techniques that scientists use to determine how, and how fast, the earth is changing Entries on the scientists and organizations who study these developments and who attempt to predict what will happen to the earth in the future Discussions of policies and measures that can be implemented on a local level that will allow a sensible balance between sustainability and development Written by leading scientists who have spent years studying the phenomena, the encyclopedia hopes to provide a strong foundation for understanding current controversies, and is written on a level that is understandable to scientists and other interested readers alike

Approches spatiales des zones humides dans le PNRZH

International audienc