Bedeutung der Kontinuität von Lebensräumen für den Naturschutz : Untersuchungen an waldbewohnenden Laufkäfern (Coleoptera, Carabidae) mit Beispielen für methodische Ergänzungen zur Langzeitforschung : Die Bedeutung ökologischer Langzeitforschung für Naturschutz

1998

S. 191-214

54 Lit. Ang.

Unselbständiges Werk

200080572

During the Middle Ages and modern times (until about 1800), woodlands of the lowlands of north-west Germany were reduced to smal remnants. In the last 200 years the area covered by woodlands has been considerably increasing due to modern forestry. Therefore it is possible to distinguish between ancient and recent woodlands. The distribution fo ancient woodland was reconstructed by analysing historical mappings and literature. By pitfall traps, 57 woodlands, 25 ancient and 32 recent ones, were studied with respect to their carabid communities. Ancient woodlands show a significantly higher number of species characteristic for woodlands. In north-west Germany, Carabus glabratus and Abax parallelus are exclusively or mainly restricted to ancient woodland. But most woodland-dwelling carabids (e.g. Carabus problematicus) have been able to colonise recent woodlands in the last 200 years. In order to analyse the power of dispersal of the relict species C. glabratus and the widely distributed C. problematicus, the following investigations were done: (1) determination of the recent distribution of both species in a contiguously wooded area containing small remnants of ancient woodlands by pitfall trapping; (2) tracing of beetles in the habitat by harmonic radar; (3) determination of the tendency to leave the natural habitat and disperse into heath and juniper shrubs by pitfall trapping. The results indicate a lower locomotory activity and therefore a lower power of dispersal for the relict species C. glabratus. An allozyme survey shows small differences between local populations within contiguously wooded areas. This may be due to a low population dynamics which would explain how C. glabratus survived the Middle Ages and early modern times in small remnants of woodlands, particularly if it is taken into consideration that this ground beetle is hardly able to refund new populations due to its low power of dispersal. For a better understanding of population dynamics, indirect methods to reconstruct population histories (e.g. analysing historical information, population genetics) are recommended as important additions to long-term studies. Additionally, the meaning of ancient woodlands for nature conservation is discussed, especially because of their irretrievability and their substantial number of both animal and plant relict species. Consequences for nature conservation management and a strict protection of these habitats are required.