Query: keyword: "Trends"
|Authors||Y. Gonseth, C. Monnerat|
|Title||Recent changes in distribution of dragonflies in Switzerland (Odonata)|
|Publisher||European Invertebrate Survey - the Netherlands|
|Book/source title||Changes in ranges: invertebrates on the move. Proceedings of the 13th International Colloquium of the European Invertebrate Survey, Leiden, 2-5 September 2001|
|Editors||M. Reemer, P.J. Helsdingen, R.M.J.C. Kleukers|
|Keywords||Odonata; Switzerland; Faunistics; Red list; Conservation; Trends|
|Abstract||Recent changes in distribution of dragonflies in Switzerland (Odonata) |
In 1998 the Swiss Centre for the Cartography of Fauna (CSCF) initiated ‘Odonata 2000’. This project aimed at testing a method for periodical reassessment of Red Lists in Switzerland. The study was carried out on Odonata and consisted of the resampling of known localities of threatened species and the sampling of new localities. Based on the number of sites where a given species has been found in the periods 1970-1998 and 1999-2000, trends were calculated for each species. The results show that since 1994 three species have disappeared from Switzerland, nine species have declined, two species have increased and 64 species have remained stable. Crocothemis erythraea, Lestes virens, Nehalennia speciosa, Sympetrum depressiusculum and S. pedemontanum are discussed as examples of the different trend categories. The authors conclude that the situation is worse than in 1994 and that the conservation of threatened species should not only focus on their last remaining habitats, but also on increasing the number of favourable sites.
|Download paper|| http://www.repository.naturalis.nl/document/46391 |