HABITAT TYPOLOGIES AND CONSERVATION OF BIODIVERSITY

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HABITAT TYPOLOGIES AND CONSERVATION OF
BIODIVERSITY Pierre Devillers, Jean
Devillers-Terschuren and Roseline C.
Beudels-Jamar Royal Belgian Institute of Natural
Sciences, Conservation Biology
The principal mechanism that drives the
biodiversity crisis, threatening species,
populations and biocoenoses, is habitat
destruction, fragmentation and degradation. The
establishment of coherent networks of areas under
diverse levels of protection is the most adequate
corrective measure and at the core of
conservation strategies. Adapted to the
conservation of the biological values targeted,
these networks are usually capable of preserving
most species and the communities they constitute.
Overall conservation measures applied in the rest
of the environment bring a complement of
protection to less sensitive species and less
fragile communities. The individual sites that
compose the networks are chosen for their
contribution to the overall diversity of the
system, to the complex requirements of a species
or a community, or to the representation of the
spectrum of their geographical and ecological
variation. Some sites are established for the
preservation of threatened or patrimonial
species, with requirements that exceed those of
most members of the communities to which they
belong. For these sites, data about the target
species are, and will remain, the best source of
criteria for site selection. Other sites, perhaps
a majority, should be dedicated to the
conservation of the entire regional diversity.
The definition of criteria for their selection is
a central preoccupation of conservation biology.
The total diversity of species, populations and
interactions cannot be accurately inventoried,
even less included in legislation. Resorting to
surrogate variables is thus inescapable.
Traditionally, surrogates have been indicator
species or groups of species. Although this
approach, illustrated, in particular, by the
hotspot methodology, has had undeniable
successes. It has, however, shown its
limitations. At the small scales of spatial
resolution characteristic of conservation areas
world-wide, networks established for distinct
taxonomic groups are not congruent. It appears
that a methodology based on the recognition of a
sufficiently detailed array of habitat units
offers an operational alternative. The holistic
approach that it constitutes insures a less
uncertain link between the units taken into
consideration and their constituting elements
than that which might exist between two unrelated
taxonomic groups. At the same time, the
integration effect of these units permits the
consideration of a much smaller list of entities
than the full array of species that contribute to
their construction.
Species lists
Target species
Species-orientedconservation areas
Hotspot conservation
Indicator species
Silent diversity
Flagship species
Surrogate indicators
Habitat lists
Habitat typologies
Target communities
Habitat-oriented conservation areas
The Physis typology, derived from the methodology
developed for the CORINE-Biotopes project,
provides a framework to organise in an ordered
sequence the habitats of the world. Within its
scheme a habitat is a three-dimensional spatial
entity that comprises at least one interface
between air, water and ground spaces and includes
both the physical environment and the communities
of plants and animals that occupy it. Habitat
definitions depends on the scale at which they
are considered. The level of resolution of the
Physis typology is that of the ecological
requirements of small vertebrates, large
invertebrates and vascular plants. A unit in the
Physis habitat typology is a habitat type, thus a
characterisation of a collection of spatial
entities sufficiently alike in abiotic
conditions, physiognomy, composition of plant and
animal communities to play similar roles from the
point of view of nature conservation. There is an
unavoidable degree of arbitrariness in deciding
whether two communities are sufficiently similar
to be referred to the same unit, or conversely,
sufficiently different to warrant distinctive
treatment. For plant communities,
phytosociological criteria were used to assess
degree of divergence and its relevance to
sensitive species. For animal communities, data
are often lacking precisely for the groups most
in need of habitat conservation rather than
species-specific programmes. All habitat
classifications use, alone or in combination,
similarities in physiognomy, abiotic conditions,
plant community composition, plant dominance,
plant community succession and, sometimes, animal
community composition to combine elementary units
into collective entities of successively higher
rank. The priority given to the various criteria
and the ensuing classifications are necessarily a
matter of choice. The guideline of the Physis
habitat classification has been to use
large-feature physiognomy, plant-community
composition and biogeographical or ecological
factors underpinning animal-community
composition, in that order. The scheme allows for
evolution of the hierarchy as understanding of
the habitats of a geographical area improves, as
new needs of identification arise, as an
increasing portion of the total geographical area
concerned is examined in detail without affecting
previous applications of the list. The method
has, so far, been applied to three
biogeographical realms. It has resulted in the
constitution of three databases, accompanied by a
number of satellites and excerpts
A classification of Palaearctic habitats
Habitats of South America
Habitats of Africa
The Physis habitat typology, and its predecessor,
the CORINE-Biotopes habitat typology, have had a
number of applications, at continental, regional
and local scales. Among them
The CORINE-Biotopes inventory of sites of
European Community significance for nature
conservation was based on species-oriented and
habitat-oriented criteria. The latter resulted in
a larger number of identified sites, in
particular, in regions of diffuse distribution of
species.
Council Directive 92/43/EEC of the European Union
on the conservation of natural habitats and of
wild fauna and flora. Appendix 1, listing
habitats to be included in the Natura 2000
Network was constructed on the basis of the
CORINE-Biotopes typology.
Keys to habitat identification at the regional
level have been derived from the Physis typology,
in particular, in the Walloon Region of Belgium.
The Physis typology was directly instrumental in
establishing a list of priority habitats for the
Bern Convention. It is one of the tools of
construction of the Emerald Network of sites
being identified throughout Europe at the
initiative of the Council of Europe.
Developments envisaged Extension of the
continental frameworks to other parts of the
world.Improvement of detailed regional coverage
of existing continental typologies.Mapping of
typology units.Investigation of scale
factors.Validation of adequacy in coverage of
silent biodiversity.
Annex I. Natural habitat types of community
interest whose conservation requires the
designation of special areas of conservation
Interpretation Code The hierarchical
classification of habitats produced through the
Corine programme (Corine biotopes project) is the
reference work for this Annex. Most types of
natural habitat quoted are accompanied by the
corresponding Corine code.
Clé d'identification provisoire des habitats de
la Région wallonne La clé est formée d'une série
de tableaux. Chaque tableau offre un choix
multiple dont les options correspondent à des
cases. Dans chaque case se trouve un texte d'aide
au choix, une borne d'information et une borne de
sortie.
www.naturalsciences.be/cb/