Relationships between the duration of snowlie and the distribution of bryophyte communities within snowbeds in Scotland

Snowbeds in Scotland are on the extreme edge of their geographic range and are thus at particular risk from the threat of climate change. Three bryophyte-dominated communities typical of late Scottish snowbeds; the Polytrichum sexangulare–Kiaeria starkei community, the Marsupella brevissima–Anthelia juratzkana community and the Pohlia ludwigii community, were surveyed along gradients of snowlie duration. Regression analysis showed that within snowbeds the Marsupella–Anthelia community is negatively associated with prolonged snowlie, and the Polytrichum–Kiaeria community is positively associated with prolonged snowlie. The relationship between the distribution of the Pohlia community and snowlie is less clear, but was observed to be strongly influenced by substrate moisture content. The Kiaeria–Polytrichum community, as that most closely associated with proloned snowlie, is likely to be the community most potentially at risk from climate change.