CarHab is a national cartographic modeling program for natural and semi-natural habitats in France.

Presentation of the catalog

Initiated as part of the national biodiversity strategy 2011-2020, this program led by the Ministry in charge of ecology aims to meet the challenges of biodiversity conservation, land use planning and sustainable management of natural resources. Its objective is to carry out by 2025 a national mapping of natural and semi-natural habitats for the terrestrial ecosystems of mainland France and the French overseas territories, at a scale of 1: 25,000th, in close collaboration with naturalist experts from the National Botanical Conservatories (CBN). The results must make it possible to fill the knowledge gaps on habitats and will support national and territorial public policies related to land use planning and knowledge of biodiversity. They will also make it possible to better respond to community commitments linked to the Habitat-Fauna-Flora Directive, in particular for monitoring and evaluating the state of conservation of habitats of community interest.

Objects of study

Three objects of study are considered in the CarHab program:

  • Biotopes: they consist of ecologically homogeneous surfaces (identical edaphic and climatic conditions), within which constant ecosystem potentials are expressed (biocoenosis, syntaxons, identical functionalities). They constitute the surface support of the vegetation series (temporal successions of vegetation stages). The definition of biotopes is based on the combination of 8 parameters: coastal character, thermal stage, shade climate, continentality, bioclimatic variant, soil moisture, soil acidity and duration of snow cover. The biotope maps are obtained by Random Forest type modeling. Example of a biotope: Biotope in the interior position of the alpine stage under a humid shade in a suboceanic situation (variant: none), on very acidic, mesophilic soil marked by medium snowfall (5-6 months) with rare and / or short winter snowfall.

Map of biotopes in the Loiret department produced in 2019

Map of biotopes in the Loiret department produced in 2019

Map of biotopes in the Loiret department produced in 2019

  • Vegetation physiognomies: physiognomies correspond to the main stages of development of plant communities during the natural time dynamics of vegetation. They are listed within a hierarchical typology.
    Example of physiognomy of vegetation: High Landes dominated by Ericaceaes.
  • Habitats: they come from the combination of information from the modeling of biotopes and that of the physiognomy of vegetation; each polygon resulting from this crossing containing information relating to the biotope (combination of the 8 edaphic and climatic parameters) and on the physiognomy of corresponding vegetation (stage in the dynamics of vegetation development). The connection of these two pieces of information to habitats from typologies (ex. Habitats of Community Interest, EUNIS) is carried out using correspondence tables.
    Example of habitat: Landes in Rhododendron ferruginous alpine.

Structures involved in production

The wide range of skills required for the implementation of the CarHab program (naturalists, IT, biostatistics, data administration, dissemination and promotion) requires the involvement of a large network of actors and structures located throughout France and acting in concert to achieve the objectives defined by the ministry in charge of ecology. The following structures are the main players in the program:

  • Ministry in charge of ecology
  • National Botanical Conservatories (CBN): they are involved throughout the process by providing their expertise on natural environments (drawing up departmental catalogues, providing learning data, validating models, establishing correspondence tables, etc.).
  • UMR 5600 EVS ISTHME: in charge of biotope modeling (assistance for the development of departmental catalogs, design of explanatory variables, cartographic modeling, statistical evaluation of results, etc.).
  • National Institute of Geographic and Forest Information (IGN): in charge of modeling vegetation physiognomies and production of segmentation polygons into which the results of the modeling of vegetation biotopes and physiognomies are poured. The IGN also ensures the link with certain scientific partners supporting the program, concerning the physiognomy of vegetation (CESBIO in particular).
  • UMS 2006 PatriNat (OFB, MNHN, CNRS): in charge of coordinating the production of biotopes, management and dissemination of data related to the SINP, conversion of results into data on habitats related to the national HABREF repository, support for biotope modeling, dissemination of results, scientific and technical support to the ministry in charge of ecology.
  • French Biodiversity Office (OFB): in charge of coordinating the production of biotopes and physiognomies with the UMS PatriNat and IGN and the technical and administrative management of agreements with the National Botanical Conservatories.
  • BRGM : in charge of the production of the geological reference layer used in the modeling of biotopes from France mainland. This homogeneous layer is generated from harmonized 1:50000 geological maps which are expertly translated into a nomenclature at the interface between geology and ecology.