Vegetation and climatec. 12 300–9000 cal. yr BP at Andøya, NW Norway

Abstract

Owing to proximity of the North Atlantic Stream and the shelf, the Andøya biota are assumed to have responded rapidly to climatic changes taking place after the Weichselian glaciation. Palynological, macrofossil, loss‐on‐ignition, tephra and14C data from three sites at the northern part of the island of Andøya were studied. The period 12 300–11 950 cal. yr BP was characterized by polar desert vegetation, and 11 950–11 050 cal. yr BP by a moisture‐demanding predominantly low‐arcticOxyriavegetation. During the period 11 050–10 650 cal. yr BP, there was a climatic amelioration towards a sub‐arctic climate and heaths dominated byEmpetrum. After 10 650 cal. yr BP theOxyriavegetation disappeared. As early as about 10 800 cal. yr BP the bryozoanCristatella mucedoindicated a climate sufficient forBetulawoodland. However, tree birch did not establish until 10 420–10 250 cal. yr BP, indicating a time‐lag for the formation ofBetulaecotypes adapted to the oceanic climate of Andøya. From about 10 150 to 9400 cal. yr BP the summers were dry and warm. There was a change towards moister, though comparatively warm, climatic conditions about 9400 cal. yr BP. The present data are compared with evidence from marine sediments and the deglaciation history in the region. It is suggested that during most of the period 11 500–10 250 cal. yr BP a similar situation as in present southern Greenland existed, with birch woodland in the inner fjords near the ice sheet and low‐arctic heath vegetation along the outer coast.