A Late-glacial/early Holocene pollen diagram from Utsira is interpreted as showing six main climatic periods: (l) The pleniglacial period from deglaciation (probably before 14,000 BP) to ca. 13,000 BP with an Artemisia pioneer vegetation on disturbed mineral soil. (2) The Bølling (BØ) amelioration (ca. 13,000 to ca. 12,300 BP) with a Salix shrub dominance on humus soils. (3) The 'Older Dryas' (OD) deterioration (ca. 12,300 to ca. 12,000 BP) with a recurrence of herb dominance. (4) The Allerød (AL) amelioration (ca. 12,000 to ca. 11,000 BP) with the re-establishment of Salix shrubs. Two minor climatic deteriorations are traced at about 11,750 and 11,300 BP. (5) The Younger Dryas (YD) Stadial (ca. 11,000 to ca. 10,000 BP) with a dominance of Sedum and other mineral-soil herbs. (6) The early Holocene with locally established woodlands of birch, hazel and Populus. July means of 7-to•c in the pleniglacial, 12-t4•c from BØ to AL, lOOC in the first half of YD, 12-l4°C in the last half, and at !east 14-16°C in the early Holocene are indicated. Strong winds may have prevailed throughout the Late-glacial, inhibiting woodland development. In periods of climatic deterioration, colder winters and increased wind activity are suggested as the main factors deleterious to humus-soil vegetation. Boreal-circumpolar, arctic-alpine, and eurasiatic plants dominated the Late-glacial flora.
Late Weichselian and early Holocene vegetation, climate and floral migration at Utsira, North-Rogaland, southwestern Norway