CarHab

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 terrestrial habitats of mainland France and the French overseas territories, at a scale of 1: 25,000^th.

The results should provide information on the location of 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 the distribution of habitats of community interest.

Subjects of study

Three objects of study are considered in the CarHab program:

• Biotopes: hey consist of ecologically homogeneous surfaces (identical edaphic and climatic conditions within which constant ecosystem potentialities are expressed (identical biocoenoses, syntaxons, functionalities).

They constitute the surface support of vegetation series (temporal successions of vegetation stages). The definition of biotopes is based on the combination of 8 parameters: coastal character, vegetation stage, ombroclimate, continental character, bioclimatic variant, soil moisture, soil acidity and duration of snow cover.

Modeled map of biotopes in the Cher department

• Vegetation physiognomies: physiognomies correspond to the main stages of development of plant communities during the natural time dynamics of vegetation.
The modeled maps contain 26 physiognomy classes.

Example of physiognomy of vegetation: Mown grassland.

Modeled map of the vegetation physiognomy in the Cher department

• CarHab 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 contains 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).

Mown grassland in the interior of the montane level under a hyperhumid umbroclimate in a sub-oceanic situation, without bioclimatic variants, on basic, humid soil with a circulating water table marked by no to short snow cover (0-4 months)

Modeled map of natural and semi-natural habitats in the Cher department using a simplified legend

Maps derived from modelling

The habitats modelled by the CarHab programme are matched with the European EUNIS habitat typology and the Habitats of Community Interest.

Map of EUNIS habitats predicted in the Cher (left), map of Habitats of Community Interest "9120 Atlantic acidophilous beech forests with Ilex and sometimes Taxus undergrowth" predicted in the Cher (right).

Machine-learning modelling using existing vegetation data, image analysis techniques and field prospection

The biotope and vegetation physiognomy maps for each department are produced by supervised modelling using a Random Forest algorithm. The National Botanical Conservatories provide the training data for the model from existing data on their territory. For the vegetation physiognomy, the modelling from satellite images (Sentinel-2) is completed by information layers from the BD Forêt® and the BD TOPO® of the IGN. For biotopes, the modelling is based on geographical information layers of environmental variables (topography, climatic data, geology, pedology, sunshine, etc.). A field survey phase is used to refine the model.

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 actors of the programme:

• Ministry in charge of ecology: project management and strategic steering
• French Biodiversity Office (OFB): in charge of the technical and administrative management of the agreements with the national botanical conservatories and in support of their annual planning.
• PatriNat (OFB-MNHN-CNRS-IRD): in charge of the scientific and technical coordination and the steering of the operational deployment of the programme. Ensures the dissemination of data in connection with the SINP via the creation of an online cartographic visualisation tool.
• National Institute of Geographic and Forest Information (IGN): in charge of modelling vegetation physiognomy and cross-referencing biotope and vegetation physiognomy data.
• EVS UMR 5600 University Jean Monnet Saint-Étienne: in charge of biotope modelling (design of explanatory variables, cartographic modelling, statistical evaluation of results, etc.).
• National Botanical Conservatories (CBN): they are involved throughout the process by providing their expertise on natural environments (providing training data, validating models, establishing correspondence tables, etc.).

CarHab data dissemination

Map of the 20 departments disseminated in April 2023

Download CarHab data

View CarHab data

An online map viewer allows you to see the data produced by Carhab, to filter the data displayed, and to download the data department by department.

Access to the map viewer