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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.
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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.
