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Sources : Devillers P., Devillers-Terschuren J. & Vander Linden C., 2001. PHYSIS Palearctic Habitat Classification. Updated to 10 December 2001. Institut Royal des Sciences Naturelles, Bruxelles.

A classification of palaeartic habitats

Classification des habitats naturels et semi-naturels du domaine paléarctique.


The PHYSIS system of habitat classification was originally developed as part of the CORINE (CoORdination INformation Environment) programme of the European Union for the selection and description of sites of nature conservation importance. First conceived in 1985, the European catalogue was presented as a draft list by the Council of Europe in 1986, then as a part of the CORINE Biotopes manual by the Commission of the European Communities in 1991. It was later extended to Central and Northern Europe, then, with the collaboration of the Council of Europe, to the entire Palaearctic region, the new, expanded, version being published by the Council of Europe in 1996. This Palaearctic catalogue is still being completed and updated.

As the CORINE Biotopes habitat list encompassed progressively larger geographical areas, it appeared useful to expand its underlying methodology into a global habitat cataloguing system that could provide a flexible integrating tool to evaluate the nature conservation significance of homologous habitats on different continents and assist, in particular, the Biological Diversity Convention in selecting and assessing networks of protected areas. The selection of sites to be included in conservation networks and the evaluation of the adequacy of such networks rests, of course, in large part on the known needs of threatened or representative species, in particular of flagship species. However, it should also rest on identification and cataloguing of representative habitat types, both to preserve the webs of interactions that, beyond the juxtaposition of species present, characterize communities, and as a surrogate for the consideration of large number of less obvious and less understood species for which particular efforts are unrealistic.

The system of habitat classification proposed by PHYSIS is based on the matrix-use of two sets of upper category describers, the biotic realms of the I.U.C.N. bio-genetic reserve network system (Udvardy, 1975), on the one hand, and a list of upper units of habitats of global application, on the other hand. Upper units of habitat within any realm are designated by combination of a realm identifier with a biotope class number of two digits placed to the left of the decimal point. The global definition of these upper units provides the intercontinental integrating mechanism. Within each realm, each of those upper divisions is divided into a hierarchical ensemble of lower divisions, characterised by digits to the right of the decimal point. These hierarchies and lower divisions are specific to each realm and not necessarily homologous between upper units formed with the same biotope digits, but different realm identifiers.

The elementary units are chosen so as to be as close as possible to entities recognized by local users, within the systems of habitat or vegetation description currently employed in their area. This approach is a key feature of the system in that it permits the construction of a typology of biocenoses, or habitats, without much new theoretical work, and without need to resolve conflicts of perspectives and emphases between various research schools. The hierarchy adopted within the realm provides the link and comparison tool between the local units and the description schemes that have generated them.

The PHYSIS methodology has been tested on a variety of different habitat classes on all continents. Complete frameworks have been designed for the Palaearctic, South America and Africa, with medium-resolution developments completed for the first two realms and parts of the third. The system has shown the capacity to remain compatible with many local, national or international schemes, to permit straightforward extension to progressively larger areas, including parts of polar, temperate, subtropical and tropical regions, to be very suitable for varying the degree of resolution according to local needs and availability of information, to permit friendly communication with species-based habitat identification systems or parametric systems of habitat classification.

To consult the existing PHYSIS data bases click on the geographical realm buttons below. Local extracts, when they exist, are reached through the presentation page of their respective realm. To obtain more information on the PHYSIS methodology and the history of the PHYSIS scheme, click on the left button at the bottom of the page. All documents beyond this point are scientific working documents presented in the language they were created. They may be cited as indicated in their introductory pages. To return to the main data bases page, click on the central button at the bottom of the page. To return to the home page of the Section of Conservation Biology, click on the "home" button.


Royal Belgian Institute of Natural Sciences