Threatened Mire Species
The vegetation found on natural mires is largely determined by the presence or absence of nutrients, and the hydrological regime. Other ecological factors relate to the presence of spruce trees, pine trees, alkaline fens, springs, or flooded grasslands. Under different combinations of these factors, countless distinct types of mire habitat can form - in Finland alone over 100 distinguishable mire types have been described, each with their own characteristic range of species.
About a quarter of all Finland's native plant species are associated with mire habitats, while 80 of the country's approximately 235 breeding bird species are dependent on the continued existence of mires during at least some stage of their life cycle. The rare Frigga's fritillary (Clossiana frigga) is typically found in pine mires, but has disappeared from much of its former range in southern Finland, probably due to changes in local microclimates induced by drainage.
Fertile, nutrient-rich mires have inevitably been most intensively drained, and indeed the characteristic species of such habitats have declined most markedly. About two-thirds of the mire species under threat are characteristic of nutrient-rich fens and spruce mires. Widespread drainage has also made it harder to find more familiar mire species such as cranberries and cloudberries. Nowadays new drainage schemes are very rare, but old ditches are still cleared out periodically.
Mire species endangered by drainage and peat extraction:
Source: Suomen lajien uhanalaisuus 2000 (Threatened species in Finland, available only in Finnish).
- Threatened species in Fnland (www.ymparisto.fi)