Geological and Sociological Aspects of Epilithic Lichen Ecology at Qaanaaq (Thule), Northwestern Greenland

Abstract

Seven lichen community types of the epilithic lichen vegetation around the town Qaanaaq (Thule), northwestern Greenland, are recognized on the basis of floristic composition and different habitat factors. The main habitat factors are rock mineralogy and lithology, physical environment, and exposure and inclination of the host rock surface. The lichen vegetation was investigated by pin-point analysis.

All the lichens studied were growing on loose rock substrates, i.e., stones and boulders of the surficial deposits that dominate the ice-free coast around Qaanaaq. The rocks are locally derived; rock types can readily be correlated with in situ bedrock units. Mineral and chemical compositions of the lichen substrates were estimated from thin sections of selected rocks chosen as representative of the lichen-covered rock suite. Two of the seven lichen communities show obvious relationships to rock substratum.

The seven lichen communities are comparable to communities recognized elsewhere in Greenland, North America, and Europe, although the Qaanaaq vegetation is relatively simple, being composed of rather few species.