Porella obtusata: distribution, ecology and threats at the west coast of Norway, the northern fringe of its European distribution

Abstract

Porella obtusata is a liverwort with a southwestern distribution in Europe. In Norway it is confined to areas with oceanic climate along the west coast, where it also reaches its northern limit. Typically it is growing on sunlit, base rich rocks at sea level in southwestern Norway, a scarce habitat in these coasts dominated by granitic bedrock. There are some old records, but investigations after year 2000 have yielded much new information. Porella obtusata is a rare species in Norway, and the new information shows that its habitat is threatened by exploitation and shrub encroachment of the shoreline.