The Late Devensian flora and vegetation of Britain

• Published in: Philosophical Transactions of the Royal Society of London. B, Biological Sciences
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 1977
• Subjects: Arctic; Berglund
• Online Access: http://dx.doi.org/10.1098/rstb.1977.0109; https://royalsocietypublishing.org/doi/pdf/10.1098/rstb.1977.0109

For the period ca. 15000-10000 years ago, which spans the interval between the latest presence of lowland ice and the final disappearance of mountain glaciers from Britain, so many botanical data are now available that it is possible to analyse plant distributions and vegetation composition in detail not yet possible for earlier periods. Species lists, provided by identification of pollen and of macroscopic remains, show a combination of diverse phytogeographic elements into an assemblage characteristic of the period - an admixture of apparently thermophilous plants with those now found in northern and arctic situations, and of oceanic and steppe elements. Ordination of data on floras has revealed much similarity between the regions of Britain, but pollen analysis continues to emphasize how strong must have been the regional differentiation of vegetation. A comparison of pollen diagrams published since 1970, from sites lying on a broad north-south transect of western Britain, shows much variety in the pollen assemblage zones which have been distinguished, and in the vegetation interpreted from the pollen data by comparison with surface samples and modern vegetation. Sufficient 14C dating is now available, however, to permit chronostratigraphic correlation of these pollen zones, and to show that there is consistent evidence for climatic amelioration at about 13000 B.P., and rapid deterioration at about 11000 B.P., leading to conditions of incomplete vegetation cover and universal soil disturbance which can be correlated with geomorphological evidence for the recrudescence of mountain glaciation in western Scotland, the Lake District, and North Wales, in the period called Younger Dryas on the continental mainland. Between 13000 and 11000 there is in western Britain evidence for a woodland biozone, or palaeobotanical interstadial, equivalent to Bolling plus Allerod of continental stratigraphers (Mangerud, Andersen, Berglund & Donner 1974), and divided by a very minor regression of vegetation during Older Dryas ...