141 Vegetational History of Central Scotland SUSAN RAMSAY & JAMES H. DICKSON Division of Environmental and Evolutionary Biology, Graham Kerr Building, University of Glasgow G12 8QQ Summary The vegetation history of central Scotland has been summarized from information obtained primarily from pollen analysed sites in the region. Open ground taxa began to be replaced by a dwarf shrub community during the late-glacial period but this process was reversed by the Loch Lomond glacial readvance. Following this cold period dwarf shrubs again migrated into the area. These were gradually followed by the major tree taxa until, by the time of maximum woodland expansion, central Scotland was covered by mixed deciduous woodland with small amounts of Scots pine growing on drier areas of peat bog. The expansion of the human population led to increasing woodland clearance and by the Iron Age extensive clearance of the woodlands of central Scotland was underway. Over the last 2000 yr changes in population have resulted in corresponding changes in the wood- land cover of central Scotland and have led to the deforested landscape seen today. Introduction This paper reviews current knowledge of the vegetation history of central Scot- land from approximately 30,000 years ago to the present day. For the purposes of this paper central Scotland has been defined as the area enclosing the Forth and Clyde Valleys, extending as far north as Fife and including the island of Arran. All dates are given as radiocarbon years (bp - before present 1950) and as calibrated calendar years (cal BP, cal BC or cal AD) after calibration with the OxCal calibration program. Sites mentioned in the text are shown on Fig. 1 and detailed in Table 1. See Tipping (1994) for a more complete list of pollen analysed sites in Scotland. Late Middle Devensian The oldest studied sediments in this area are those from a sub-drumlin layer at Sourlie, Ayrshire, which are well radiocarbon dated to c. 30,000 yr bp (Jardine, Dickson & Coope, 1988). The biological results (J.A.A. Bos, J.H. Dickson & R. Coope unpubl.) include evidence from pollen, plant macrofossils and inverte- brate remains, especially Coleoptera. In summary the vegetation was a grassy, sedgy, herb- and moss-rich tundra with a low-growing shrub community com- prised mainly of Salix and Betula nana. The full account of this work will provide a detailed picture of the environment of this area during the pleniglacial (full- glacial) period. Devensian Late-glacial and Early Holocene The investigation of late-glacial vegetation in central Scotland has been ham- pered by a lack of radiocarbon dated pollen diagrams. Many of the published sites were studied before radiocarbon dating was available or routinely applied to pollen sequences. As a result the timescales applied to vegetation changes during Bot. J. Scotl. 49(2), 141-150