HOLOCENE VEGETATION HISTORY AND HUMAN IMPACT AT BRYN-Y-CASTELL, SNOWDONIA, NORTH WALES

Three radiocarbon-dated pollen diagrams are presented from Holocene pe at and lake deposits in Snowdonia, close to the Late Iron Age/Romano-B ritish ironworking hill-fort of Bryn y Castell, Gwynedd, in upland nor th Wales. This paper discusses pollen, charcoal and peat-stratigraphic evidence for major local vegetation changes and for the development o f the surrounding cultural landscape during the last 10 000 radiocarbo n yr. Pollen data from one of the sites (BYC 2) provided a vegetationa l record for most of the Holocene. The early part of the sequence sugg ests an oligotrophic lake in a landscape that is being colonized by bi rch-pine woodland; later, mixed deciduous woodland surrounds an infill ing lake basin. Dating of peat deposits at two of the sites (BYC, BYC H) indicated that their pollen records commenced between 5500 and 5000 yr sp. By this time, the lake basin was fringed by alder carr. There followed a gradual and then, c. 2700 yr sp, a more abrupt decline in w oodland, such that, by the end of the Bronze Age and with the basin la rgely terrestrialized, the local landscape became dominated by mire ve getation communities, which have persisted to the present. Human activ ity seems to have been a major factor in the loss of woodland cover. A lthough there is some circumstantial evidence for earlier phases of hu man disturbance at BYC 2, human activity becomes increasingly apparent from c. 5000 yr BP. During the mid Holocene, the impact of Neolithic and early- to mid-Bronze Age cultures appears to be characterized by t emporary woodland clearances, for arable and pastoral agriculture. By c. 2700 yr sp the majority of woodland cover seems to have been perman ently removed from the landscape, but as there is scant archaeological evidence for late Bronze Age cultures in this part of Snowdonia, othe r factors, especially climate change, could be implicated. During the late Holocene, especially during part of the late Iron Age and Romano- British period, remaining local stands of woodland seem to have been e xploited for iron smelting, although the overall impact of ironworking was limited.