STUDIES IN THE VEGETATIONAL HISTORY OF MID‐WALES

S ummary Pollen analysis has been conducted upon a mire site at an altitude of 312 m on the Mynydd Bach region of western Cardiganshire. The sediments subjected to analysis began forming at the close of the post‐Allerød cold phase (zone III sensu Godwin) and document vegetational history in the area up to the time of the elm decline, after which deposits appear to have suffered interference by peat cutting. A number of the features present at this westerly site are of particular interest, especially the early rise of Corylus in the Flandrian. Corylus pollen (expressed as % arboreal pollen) began to rise at this site before the zone III/IV Juniperus peak. As one moves progressively north in western Britain, so the Corylus rise is delayed until well after the juniper peak. This time lag is considered to reflect the migration rate of Corylus as well as offering an opportunity to trace its route up the western edge of Britain, gradually extending eastwards and into regions of higher altitude. Pine values are low at Gwarllyn throughout the early Flandrian, in contrast to the upland areas of Cardiganshire, where pine increases to a maximum in zone VIc, It is postulated that Pinus was less successful in the western lowlands as a consequence of the greater competitive ability of Quercus under the prevailing climatic and edaphic conditions in those regions.