Heidi Demolder

The status of two boreo-alpine species, Somatochlora alpestris and S. arctica, in Romania and their vulnerability to the impact of climate change (Odonata: Corduliidae)

It is expected that climate change will have a great impact on many species and habitats. This will be greater if populations are found at the edge of their range or are isolated, and could lead to regional extinction. Here we investigate the possible impact on two boreo-alpine dragonfly species, Somatochlora alpestris and S. arctica, at their range margins. Both species were unknown for most parts of south-eastern Europe. In 2007 we found 15 localities for S. alpestris and two for S. arctica in the Carpathian Mountains of Romania. Both species are there confined to mountain peat bogs. All localities are situated between 1300 m and 2100 m altitude, with the majority restricted to a small range between 1600 m and 1800 m. Based on the factor altitude we predict a hypothetical distribution map for S. alpestris. The underlying models exclusively rely on the ultimate factor “altitude” and explain more than 60% of the deviance. In addition, we assessed the impact of climate change for two scenarios: a 1.5°C temperature increase and a 3°C increase. The first resulted in altitudinal range shifts of +200 m and in a distributional shrinkage of 40%, the latter corresponds to an upward range shift of 600 m and a loss of 90% of the area. Habitat specialists, especially those at their margins of distribution, are hardly able to keep pace with climate change. It seems unlikely that mountain peat bogs will develop at rates comparable to those of current climate change. This may effect regional extinctions of boreo-alpine species.