Naturschutz-Informationen - "eigene Forschung"
T. Mattern, R. Waldhardt, A. Otte
Statutorily protection of highly endangered biotopes and biotope complexes is regarded to be one suitable strategy to ensure both biodiversity and the scenery of traditional landscapes. Considering the still-decreasing biodiversity and the abandonment of traditional land-use practices, Germany’s approx. 6,600 nature reserves appear to be highly relevant in terms of nature conservation. However, it may be asked to what extent the nature reserves established in a particular landscape cover the highly endangered biotope types and biotope complexes present in this landscape.
We conducted a study in the Lahn-Dill-Highlands (Hesse, Germany), and pursued the question whether from the spatial distribution of nature reserves in the entire region, biogeographical regions (‘Naturraum-Untereinheiten’) may be detected that are underrepresented in terms of the number of nature reserves. Additionally, we analysed differences in ecological traits between the nature reserve’s species, and those occurring in the entire landscape, and how the former reflect site conditions and historical land use of the respective reserve. We calculated spectra of Ellenberg’s indicator values  and Raunkiaer’s life-form classification for the species lists of five selected nature reserves. These were compared with the spectra of the surrounding landscape’s flora, which were derived from the according grid-cell (11 km2) in the National Floristic Survey .
The results revealed a clumped distribution of nature reserves (mainly common land pastures, moist grasslands and agri-silvicultural biotope complexes), among the biogeographical regions (Fig. 1). Most of the recent nature reserves have been located on south-exposed slopes with shallow soils. These site conditions are widespread within the region. However, in some regions where a number of highly endangered biotopes and biotope complexes are to be expected, nature reserves are even completely lacking.
The spectra of indicator values and life forms of the flora of the nature reserves and the surrounding landscape differed in many ways (Tab. 1). E.g., higher proportions of low resp. high F-indicator values in the nature reserves flora reflect their site conditions. Some of the nature reserves feature a higher proportion of therophytic species than the entire landscape. This difference is also due to the prevailing site conditions, but is also an effect of the historical land-use in the reserves. Prior to conservation anthropogenic disturbance of their habitats was considerably higher. Lack of disturbance leads to changes in habitat structure and impairs the conservational value of those reserves .
have to be established to account for spatial representativeness, and
of the existing reserves has to be efficiently adapted to meet the
of the biotic inventory.
|Version 3 - Sommer 2007|