Nicola Arndt und Matthias Pohl - Neobiota

According to SCHLÜTER (1991), heterogeneous landscape types can only be defined on the basis of a
mosaic system and singled out and mapped as spatial units.The same accounts equally for the mapping
the naturalness of vegetation at medium and small scales.
In the same way as today’s potential natural vegetation can identify the biotic potential of sites and
landscapes or their primary productivity (TÜXEN 1956), the naturalness level of today’s actual
vegetation is being considered as the key indicator for the ecological state, especially regarding the
still effective components of biological self-regulating capacities as an essential criteria for ecological
stability.
The concept of 'hemerobie' is based upon an approach to analyse the degree of human impact on a
given ecosystem. The concept had been mentioned first by JALAS (1955) and had subsequently further
developed to be applied in the context of the urban and agro-cultural environment (SUKOPP 1972;
SCHUBERT 1985; KOWARIK 1988). Through further application for the evaluation of riverine
ecosystems and of the cultural landscape in general, 'hemerobie' became more established as an
accepted methodology for assessing the naturalness. According to KOWARIK (1988), 'hemerobie' is the
"scale for the human-cultural influence” on ecosystems. Accordingly, the assessment of the degree of
hemerobie follows those anthropogenic influences, which constitute obstacles for an evolutionary
process (climax) of the (eco-)system in question.
Hemerobie assessments have already been successfully implemented. For example, as part of
UNESCO’s ‘Man and the Biosphere’ project, the Austrian Academy of Sciences launched a
hemerobie study for assessing the degree of naturalness of Austrian forests. The evaluation of
naturalness of the forest vegetation was based on a comparison of the actual with the potential natural
vegetation, examining the presence of exotic/non-native species among the trees as well understory
vegetation (GRABHERR et al. 1993).
2.3 The biogeographic context
Cultural landscapes are a product of natural processes under the influences of human activities. In
order to determine the type and degree of natural influence of a given landscape it appears as sensible
to first examine Europe’s ‘biogeographic’ context. Because of the strong influence of the
biogeographic context on human land use activities and hence on the character of landscapes,
biogeographic classes could serve as an evaluation criterion for a European-wide approach to
landscape classification and mapping.
Each climate type and their major subdivisions has a number of characteristic plant and animal species
and communities that have evolved so that they are well adapted to the range of environmental factors
in them; such characteristic biotic communities occupying an extensive area are called biomes. The
distinctions between biomes are not necessarily related to the taxonomic classification of the
organisms they contain, but rather to the life-form (the form, structure, habits, and the type of life
history of the organisms in response to its environment) of their plants and animals (COX & MOORE
1973). This concept of life-form was first put forward by the Danish botanist Christen Raunkiaer in
1903. Since animal life-forms are much less easy to recognise than are those of plants and,
consequently, most biomes are distinguished by plants they contain and are named after their
dominant plant life-forms (e.g. tundra: mosses, lichens, dwarf-shrubs, sedges; taiga: boreal coniferous
forests; temperate deciduous broadleave forests; tropical rain forests; temperate grasslands: steppes,
prairies; etc.).
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