Eine Methodik zur Auswahl von Pflanzenarten für Wiederansiedlungen : Fallstudie am Beispiel der Steppenrasen Thüringens (Deutschland)

Reintroductions of plant species are increasingly popular in conservation practice. Steppe grasslands contain many rare and endangered plant species that are potential objects for such reintroductions. Most reintroduction projects, however, can only target a restricted number of species, which raises the question of how species should be prioritised. Here, we present a method to select priority species for reintroduction based on species' characteristics that are widely used in conservation practice. We first determined the local species pool containing those vascular plant species that occurred both in our target region (Thuringia, Germany) and target habitat (steppe grasslands), yielding 369 species. With the help of an a priori filter that selected currently endangered species with limited distribution, 136 potential target species were determined. These potential target species had experienced stronger decline, had a narrower phytosociological amplitude and were more likely to be species of the Festuco-Brometea class and the Festucetalia valesiacae order than non-target species. Potential target species were then ranked by a points system based on ten conservation-relevant characteristics of the species from the categories "threat and protection status", "distribution and decline", and "habitat affiliation". In the ranking, six steppe grassland plant species (Astragalus exscapus, Bothriochloa ischaemum, Prunella laciniata, Pulsatilla pratensis subsp. nigricans, Scorzonera purpurea, and Seseli hippomarathrum) achieved the highest scores. An additional seven species not specifically characteristic for steppe grasslands also scored highly. A post hoc evaluation of these 13 highest scoring species based on additional conservation criteria left five species (Astragalus exscapus, Linum leonii, Orchis morio, Pulsatilla pratensis subsp. nigricans and Scorzonera purpurea) as species with highest priority for reintroductions and another five species as highly suitable for reintroductions. Associations between the ranking order and different ranking criteria revealed that a species’ threat and rarity in Thuringia and its protection status had the highest representation in the ranking, followed by threat in Germany, regional decline and habitat affiliation. In contrast, international threat and responsibility of Thuringia for its conservation had only low representation in the ranking, probably because these characteristics applied to only a few species. The ranking list gives a selection of species for reintroductions, which combined with additional information based on comprehensive local and floristic knowledge, allows the identification of the species with the highest priority. Our method can be transferred to other regions or habitat types.Wiederansiedlungen von Pflanzenarten stellen eine verbreitete Methode im Artenschutz dar, die auch in Mitteleuropa zunehmend praktiziert wird (GODEFROID et al. 2011). In Steppenrasen, die innerhalb Deutschlands in Thüringen einen Verbreitungsschwerpunkt besitzen, finden sich besonders viele seltene und gefährdete Pflanzenarten, die für Wiederansiedlungen in Frage kommen. Bei der Wiederansiedlung von seltenen und gefährdeten Pflanzenarten stellt sich zu Beginn einer Maßnahme zunächst die Frage nach der konkreten Auswahl der Arten, die wieder angesiedelt werden sollen. Meist ist das in Frage kommende Artenspektrum deutlich zu groß und es muss eine starke Auswahl stattfinden. Diese Auswahl sollte auf nachvollziehbaren, empirischen Methoden beruhen. Wir stellen hier am Beispiel der Steppenrasen Thüringens eine Auswahlmethodik vor, um prioritäre Arten für Wiederansiedlungen aus dem regionalen Artenspektrum zu bestimmen. Für diesen Zweck wurde anhand wertgebender Merkmale eine Rangliste nach einem Punktesystem erstellt, um die prioritären Arten für Wiederansiedlungsmaßnahmen zu erkennen. Nach unserem Wissen handelt es sich um die erste Studie speziell zur Auswahl von Zielarten zur Wiederansiedlung