PEAT STRATIGRAPHIC RECONSTRUCTIONS OF HOLOCENE CLIMATE CHANGE IN SCOTLAND

Holocene climate change was inferred from records of changing bog surface wetness (BSW) from seven sites in Scotland: six ombrotrophic raised mires and one ombrotrophic blanket mire located across geographical and climatological gradients. The key proxy indicators used were plant macrofossils, colorimetric humification and testate amoebae, which were supported by a radiocarbon based chronology, aided by analyses of spheroidal carbonaceous particles and increases in pine pollen at specific sites. Field stratigraphy was undertaken at each site in order to show that the changes detected within the peat profiles were replicable. In an attempt to identify synchroneity of climatic phases and also to aid chronological control, tephra isochrons were utilised to allow the precise linking of time-spans between sites. Fourteen tephras were identified from the seven sites, and electron probe microanalysis was used to geochemically type the tephras to known isochrons from Icelandic eruptions. The BSW reconstructions show coherent wet and dry phases over the last ca. 5000 years, with the three proxy indicators supporting each other extremely well. Key phases of climate change will be discussed, as well as key ecological changes within the bogs including the local/regional extinctions of specific taxa. Specific correlations at the time of the Glen Garry and Hekla-4 tephra isochrones revealed a significant difference between climatic phases in the north and south of Scotland. Spectral analyses of the climate reconstructions revealed identical significant periodicities from four sites, including a millennial scale periodicity which may be related to an oceanic climate forcing mechanism.