THE DEVELOPMENT OF HEATHLAND IN ORKNEY, SCOTLAND - POLLEN RECORDS FROM LOCH-OF-KNITHCEN (ROUSAY) AND LOCH-OF-TORNESS (HOY)

Pollen records from two lake sites located in areas of modem heathland were used to reconstruct the local development of this vegetation typ e. A pollen record obtained from Loch of Knitchen on Rousay covered th e last 6000 radiocarbon years. Betula-Corylus scrub was once locally p resent, although never a dominant community. Heath vegetation began to develop around 5700 BP. At about 5400 BP woodland taxa declined, poss ibly in response to Neolithic human activity, and heathland expanded. Calluna vulgaris increasingly dominated the record thereafter, reflect ing local blanket peat development. Data from Loch of Torness on Hoy c over the period from 7700 BP to around 4800 BP. Initial tall herb-type vegetation was replaced by a mixture of trees and heath taxa at aroun d 7000 BP. Arboreal taxa declined at about 6000 BP, and the subsequent record showed the development of maritime-type heath. The data show t hat heathland vegetation has been present in Orkney since at least 700 0 BP, and that a range of causal processes have been important.