EUNIS Habitat classification

Version 2.3 - February 2002

Information about the EUNIS Habitat classification:


The taxonomy for classification of species has been under development for over 200 years since the pioneering work of Linnaeus. The distinction between species is clearly understood by taxonomists, although they are not without disagreements and there are frequent revisions of some groups. Many identification guides include keys so that criteria for the differences between species can be recognised.

By contrast, although botanists have been classifying vegetation for the past century, habitat classification which builds on classical phytosociology so as to include abiotic features of the habitat is a relatively new development. The need for a classification has several driving forces: establishment of habitat protection legislation; inventory of habitats in a biogeographic region, country or site; biodiversity monitoring and reporting; description of a species' habitat requirements. A habitat classification system should be comprehensive, scientific, unambiguous and easily understood without requiring detailed technical knowledge.

In the past few decades a number of national classifications have been developed, and the first European initiatives began in the early 1980s. As a result, there are several habitat type classification systems in use for monitoring and description of habitats. These systems have many similarities, but they are not identical and reporting at European level is therefore difficult. Furthermore, different international directives and conventions have used different classifications, making their inter-relationship complex.

To meet the need, there has been a continuous work programme since the inception of the EEA undertaken for the European Topic Centre on Nature Protection and Biodiversity (formerly European Topic Centre on Nature Conservation ) by its partner the Centre for Ecology and Hydrology (formerly Institute of Terrestrial Ecology), UK. It builds upon the previous initiatives of the CORINE Habitat classification developed for the European Commission (DG XI) and its successor the (ongoing) Palaearctic Habitat classification, developed for the Council of Europe, but re-structures and re-defines this classification. It is further refined in the marine sector by the addition of units developed by marine conventions (Barcelona and Helcom) and the EU-funded BioMar project. Collaboration with the OSPAR Convention and the International Council for the Exploration of the Sea (ICES) began in 1999.

  • A novel feature of the classification, which is strictly hierarchical, is the development of criteria in order to make a key for identification of habitats, analogous to keys for identification of species. The criteria have been developed at the first three hierarchical levels. However, habitats are very difficult to define analytically and the boundaries between them cannot be determined genetically as for species, so that any classification is bound to be a compromise between different opinions. The notes which are provided together with the criteria serve to guide the user's interpretation, especially at the boundaries, and are the result of the authors' search for guidance amongst many expert contributors to the classification. They should be read carefully, since many apparent exceptions to the dividing rules are mentioned explicitly.
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    The aim during development of the EUNIS Habitat classification has been to create a common European reference set of habitat units with a common description of all units and a common hierarchical classification. This will enable referencing and reporting habitat data in a comparable manner for use in nature conservation (inventories, monitoring, assessment). It will not supplant existing national or sectoral systems, unless member countries or institutions so want. The specific requirements are that the classification should:

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    Geographical scope: pan-Europe, defined in the same way as in the report "Europe's Environment - The Second Assessment" (EEA, 1998), i.e. the European mainland as far east as the Ural Mountains, including offshore islands (Cyprus; Iceland but not Greenland), and the archipelagos of the European Union Member States (Canary Islands, Madeira and the Azores). Anatolian Turkey and the Caucasus are included in the classification in principle, although knowledge from these areas is more limited.

    Habitat is defined as: "plant and animal communities as the characterising elements of the biotic environment, together with abiotic factors (soil, climate, water availability and quality, and others), operating together at a particular scale".

    The scale of organisms and of the environmental units in which they occur is intrinsic to the definition of habitat: it is that occupied by small vertebrates, large invertebrates and vascular plants. Samples of between 1 m2 and 100 m2 will generally be adequate to categorise habitats. At the smaller scale, "microhabitats" (features generally occupying less than 1 m2 which are characteristic of certain habitat types and important for some smaller invertebrates and lower plants) can be described. Examples are decaying wood, found in mature forests and required by invertebrates whose function is decomposition, or animal dung in grassland environments. At the larger scale, habitats can be grouped as "habitat complexes", which are frequently-occurring combinations or mosaics of individual habitat types, usually occupying at least 10 ha, which may be inter-dependent. Estuaries, combining tidal water, mud flats, saltmarshes and other littoral habitats, are a good example.

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    The classification is based on general vegetation science with additions of a series of non-vegetated landscape elements, which are important animal habitats or form the basis for colonisation of vegetation. Marine elements are also included, whether or not colonised by plants or animals, including those composed of substrates of animal origin.

    The starting point was the Palaearctic Habitat classification, extended from the CORINE Habitat classification which was developed for use by the European Community in the pilot CORINE Biotopes programme by the EU Commission 1986-1991. The Palaearctic Habitat classification was developed as an extension to and beyond Phare countries (of Central and Eastern Europe) in their 1992-1998 CORINE Biotopes projects. Continuity in these two phases of CORINE Biotopes was ensured by the work being undertaken throughout by the Royal Institute of Natural Sciences in Brussels. The Palaearctic Habitat classification continues to be extended to new countries in eastern and central Europe.

    With extensions and in-depth work the Palaearctic Habitat classification has developed through several versions during more than 10 years of existence. With the advent of remote-sensing based land cover mapping, the possibilities in database development and the need to consolidate the work, the EEA has taken the responsibility to build on the Palaearctic habitat classification work, and to include habitats which were not fully represented in the Palaearctic classification, such as those in the marine environment.

    The initial stages of the EUNIS work included a re-structuring of the Palaearctic classification to fit with criteria which were developed for the identification of habitats at levels 1, 2 and 3. Habitat units which did not fit clear criteria were moved between habitat types at any of these levels as appropriate in order to make the criteria more consistent and easily understood. So as to avoid duplication of effort, the decision was made that at hierarchical levels below the third, the habitat units would be attached from contributing classifications, initially Palaearctic and BioMar (marine areas around UK and Ireland), later augmented with Mediterranean and Baltic marine habitats. The linked lower level units are clearly shown by their coding, indicated in the database by the use of the level 3 EUNIS code followed by /, a classification reference letter, and the code of the unit from the other named classification, and not by EUNIS codes of four or more characters. The classification reference letters are P, B, M and H respectively. EUNIS is thus a means whereby classification systems can be combined in a common framework. Generally the names used are those of the linked parent classification, augmented or edited only where necessary for greater clarity or consistency with other EUNIS names. In a few cases, where these could not be found in the other classifications, EUNIS habitats have been added at level 4: these are listed in the database with 4-character EUNIS codes. Units at levels 5, 6 and possibly 7 have been added only to complete the linkage to the marine classifications or to Annex I of the EU Habitats Directive.

    The work has been done in a series of collaborations - workshops, experts' meetings, consultations - with vegetation and habitat experts selected on the basis of their experience particularly with CORINE and the EU Habitats Directive or in other organisations such as The European Vegetation Survey. Experts both from EEA and Phare countries have been involved, as habitat experts, not as national representatives. Comment on the 1997 draft of the classification was sought in 1998 from over 150 experts, and results were used in further refinements. Collaboration with the OSPAR Convention and the International Council for the Exploration of the Sea (ICES) began in 1999 with a workshop of marine habitat mapping specialists held at Oban, Scotland. Following that workshop, the first definitive version of the EUNIS classification was made available through the present website, with the intention of maintaining stability for a period of one to two years.

    A review of the marine units of the EUNIS habitat classification was made during a second workshop convened by OSPAR and ICES and held at Southampton, England in September 2000. The first version of the classification was heavily biased towards British waters since the majority of units included at level 4 were those from the BioMar classification. One aim of the workshop was to develop marine units to Level 4 and to propose amendments to the present classification as required by an extension of the geographical area to include the whole OSPAR, ICES and EEA area. The classification of pelagic habitats was revised completely at a meeting of the ICES Working Group on Marine Habitat Mapping held at Galway, Ireland in April 2001. Proposals made at the Southampton workshop and Galway meeting were been included in an update of the EUNIS classification dated May 2001, and unresolved issues are highlighted in the 'Comment' field found in the habitat descriptions. Further work is required on these issues, but the update has been published so that all users can benefit from the progress made at the meetings mentioned above, and can contribute their feedback. Note that level 4 habitat units added in consequence of OSPAR/ICES workshops have been given a reference letter O where appropriate. A number of mainly small revisions to the non-marine parts of the classification remain have been made in February 2002.

    A parameter database has been built up, starting from one developed for the Nordic Council's classification of Nordic Vegetation types. The database includes reference systems for climates, soils, water quality as well as vegetation, physiographic elements, characteristic or dominant plants and animals. Further work is required to populate the database with assessments of the parameters describing EUNIS habitats. As a starting point, parameters for marine habitats have been included from the BioMar classification.

    Cross-referencing has been maintained to the classification's predecessors (CORINE and Palaearctic) at several publication dates from 1989 to 2001, to the classifications used by the marine conventions and projects mentioned above, and to the CORINE Land Cover classification. Relationships between EUNIS and the habitats listed under two legal instruments have been established.

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    Relationship to legislative lists

    The EUNIS Habitat classification is closely related to

    They all build upon the CORINE/Palaearctic Habitat classification, but because of the fixed place in legal frameworks, the EU Habitats and the Bern Convention Lists have not continued to evolve, while their parent classifications have developed further.

    The EUNIS Habitat Classification is a complete classification system, i.e. it covers in one system all habitat types, whereas the two legislative lists cover only those habitat types which at a particular time were most in need of protection through international designation.

    All habitats included in the legislative lists can be located through cross-references in the EUNIS classification.

    Habitat lists




















    European classifications














    EUNIS v.1



    EUNIS v.2


    EU Habitats Directive



    Annex I









    CoE Bern Convention





    Resolution No. 4 list







    OSPAR Convention








    1st OSPAR/ ICES/EEA workshop on Habitat classification


    2nd OSPAR/ ICES/EEA workshop on Habitat classification



    International Council for the Exploration of the Sea (ICES)










    Working Group on Marine Habitat Mapping

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