Abstract
SUMMARY: Pollen‐stratigraphic data are described from two sites on the northern face of the Brecon Beacons escarpment in South Wales, U.K. Pollen percentage, pollen concentration and deteriorated pollen diagrams are presented which contain details of vegetational changes in this part of Britain from the time period immediately following the wastage of the Loch Lomond Advance glaciers around 10000 radiocarbon years ago, until the establishment of oak and alder woodland in the mid‐ Flandrian some 4000 years later. An initial phase of juniper scrub was followed by the expansion of birch woodland over much of the area, and these forests were subsequently invaded by large numbers of hazel. Quercus, Ulmus and Pinus were present throughout the mid‐Flandrian, but increasing climatic wetness, possibly beginning around 7000 radiocarbon years ago, led to the decline of elm, pine and birch as woodland components in this part of South Wales, and to the expansion of Quercus and particularly Alnus. These vegetational changes are discussed in terms of vegetational developments at other sites in upland Wales and western Britain.