Late Quaternary vegetation history of the Western Isles of Scotland

Abstract

SUMMARY Palacoecoiocical investigations of two lake sediment sequences are used to reconstruct the vegetation history of the Western Isles. Pollen records begin in the late glacial and show a clear progression From herb‐rich grassland with abundant Salix, Rumex and Poly‐podium to widespread Empetrum nigrum heath. Woodland developed widely in the early Holocene, and regional vegetation patterns emerged. Western Lewis supported extensive areas of birch woodland with Corylus avellana, Salix, Populus and Sorbus aucuparia. Open birch‐hazel woodland dominated other lowland regions. Regional variation was accentuated when woodland underwent a sudden decline in western Lewis at about 7900 BP. Trees were replaced by blanket peat and woodland failed to recover on a regional scale after the decline‐ Woodland continued to diversify in central and eastern regions and, by 6000 BP, Quercus, Ulmus, Pinus sylvestris, Alnus glutinosa and Fraxinus excelsior had become established. Open mixed woodland persisted until the second major decline began between 5200 and 4000 UP. Woodland contracted gradually as blanket peat expanded. The Western Isles were predominantly treeless at 2500 BP. Blanket peat started to form in localized areas on the Western Isles between 9000 and 8000 BP; two main expansion phases are associated with periods of woodland decline. Sublossil wood or macrofossils are reported from a total of 40 sites. Radiocarbon ages are presented for 13 samples of these.

Neolithic settlement at the woodland's edge: palynological data and timber architecture in Orkney, Scotland

“…;de la Vega-Leinert et al, 2007). Recent palaeoenvironmental studies in the Outer Hebrides, also assumed to have supported treeless, uniform environments for much of the Holocene, have revealed evidence for the local presence of several tree species (Ashmore et al, 2000;Bennett et al, 1990b;Fossitt, 1996), and there is no reason why Orkney should not have supported similarly diverse woodland habitats. Wood was clearly available throughout the entire Neolithic period, both as a local resource and as driftwood (Dickson, 1992), providing sufficient timbers for building at Wideford (Richards, 2003) and Braes of Ha'Breck.…”

Tansley Review No. 114

“…This later decline has been clearly associated with early Neolithic settlements (Fossitt, 1996). In the Outer Hebrides, blanket peat began its appearance between 9000 and 8000 BP (Fossitt, 1996). A marked climatic deterioration (Klitgaard-Kristensen et al, 1998), commonly termed the 8200 BP event and probably due to freshwater fluxes in the final deglaciation of the Laurentide ice sheet, appears to have been ac- companied by some reduction in tree cover throughout western Europe.…”

“…In western Lewis there was a progressive replacement of trees by blanket peat which began about 7900 BP and continued with a further decline between 5200 and 4000 BP. This later decline has been clearly associated with early Neolithic settlements (Fossitt, 1996). In the Outer Hebrides, blanket peat began its appearance between 9000 and 8000 BP (Fossitt, 1996).…”

Peat initiation in the Faroe Islands: climate change, pedogenesis or human impact?

“…Solem 1986;Charman 1992;Tallis 1991;Bennett et al 1992Bennett et al , 1997Fossitt 1996;Huang 2002;Moe 2003) and other ombrotrophic mires (Smith & Cloutman 1988). The conclusion supports those who would suggest that natural processes may account for mire initiation and development in at least some instances (e.g.…”