Holocene vegetational and environmental history at Loch Lang, South Uist, Western Isles, Scotland

Abstract

A Holocene record of pollen, charcoal, magnetic susceptibility and sediment chemistry from South Uist, Western Isles, IS described and discussed. The vegetation of eastern South Uist included areas of woodland over as much as half of the available landscape during the early postglacial. This woodland was dominated by Betula and Corylus, but Quercus, Ulmus, Alnus glutinosa and Fraxinus excelsior were also present. The status of Pinus sylvestris IS uncertain. Quercus, Ulmus and A. glutinosa are now extinct as native trees in the Western Isles. During the later half of the Holocene (from about 4000 BP), woodland declined, possibly as a result of the use of hill land as grazing. Blanket peat vegetation, which had begun to spread from about 5500 HP, became the dominant feature of the landscape as the woodland areas decreased. The physical and chemical data from Loch Lang sediments suggest that little erosion of soils took place until about 550 years ago, when there vvas a marked increase, possibly attributable to increasing grazing pressure. Key words; Holocene, vegetation history, radiocarbon dating, sediment chemistry. Western Isles. INTRODUCTION°^ bedrock geology, and the treeless aspect of the Western Isles relative to the mainland at the same he Western Isles of Scotland, lying on the latitude has been explained by their greater degree of northwestern fringe of Europe and exposed to a wet exposure to wind. This introduces a strong east-west ana windy oceanic climate, are today virtually gradient to syntheses of Scottish vegetation (e.g. treeless. Their landscape is, for the most part, during the historical period [McVean & Ratcliffe, aominated by blanket peat up to several metres 1962] or at 5000 BP [Bennett, 1989], Is this view of t ick. The islands extend nearly 190 km from north the Western Isles supported by palaeoecological to south, from the latitude of Fort William to that of data? In the only modern works on the Holocene ape Wrath. Perhaps because they form a discrete vegetation history of the Western Isles, Birks & geographical unit, there has been a tendency to treat Madsen (1979) suggested that at least western Lewis e islands as uniform in vegetational terms, had been mostly treeless throughout the Holocene. a though the same latitudinal extent on the west Bohncke (1988) argued that the Callanish area, also cottish mainland coast covers a range of vegetation in western Lewis, supported local Betula woodland ypes from oak-dominated woodlands, through pine that was severely affected by anthropogenic burning, and birch to generally unforested areas of the Wilkins (1984) has drawn attention to the abundant northwest mainland. The vegetational richness and macrofossil remains of trees, including at least one variety of Skye, entirely within the latitudinal range species now extinct as a native tree in the Western o the Western Isles, are well-documented (e.g. Isles {Pinus sylvestris), within the blanket peat of irks, 1973). At least in part, there may be a Lewis and Harris. The palaeoecological and hisve...

Pollen and related studies at Kinloch, Isle of Rhum, Scotland, with particular reference to possible early human impacts on vegetation

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A transient coastal wetland: from estuarine to supratidal conditions in less than 2000 years—Boca do Rio, Algarve, Portugal

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Fluvial system response to Late Devensian (Weichselian) aridity, Baston, Lincolnshire, England

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