Local extinctions of the wetland specialist Swertia perennis L. (Gentianaceae) in Switzerland: A revisitation study based on herbarium records

We studied population extinction of the locally abundant fen plant Swertia perennis in Switzerland and used up to 127-year old herbarium records to re locate 63 sites that had once hosted this species. We recorded current site characteristics and related them to the absence or abundance of population s. Fifty-four sites (86%) were still traditionally used (extensively mown o r grazed). Fifteen populations (24%) had gone extinct. Extinction was more likely at lower altitude, in the peripheral distribution range of S. perenn is (58% peripheral, 9% central populations extinct). on the smallest fens ( 75% extinct on fens < 400 m(2)) and on fens with intensified land use. Howe ver, even on traditionally managed wetlands 18.5% of the populations had go ne extinct. Moreover, 40% of all remaining populations were smaller than 25 0 flowering plants. We conclude that both intensified agricultural practice and habitat fragmentation contributed to local extinction of S. perennis. Small populations, especially, may not be able to persist in the long term. (C) 2001 Elsevier Science Ltd. All rights reserved.