Late Devensian and Holocene palaeoecology and palaeoenvironments of the Morrone Birkwoods, Aberdeenshire, Scotland

Results are presented from analyses of pollen, vascular plant macrofossils and bryophyte remains at the Morrone Birkwoods, a site in the eastern Highlands of Scotland. The sedimentary record spans the past ca. 12 500 yr and is dated by a series of radiocarbon determinations. Quantitative palaeoclimate reconstructions are made using pollen-climate response surfaces, with the selection of analogues constrained using evidence from the macrofossil stratigraphy. The results generally are in remarkably close agreement with those reconstructed from beetle remains by Atkinson et al. The only significant discrepancy is with respect to the extent of the warming at ca. 12500 yr BP. The palaeoclimate record indicates a marked cooling that coincides in age with the ‘Older Dryas’ event and which interrupts an overall cooling trend throughout the duration of the late-glacial interstadial that culminates in the ‘Younger Dryas’. There is also evidence of a climate fluctuation during the first 500 yr of the Holocene. The mid- and late Holocene record of palaeoclimate is, in contrast, remarkably invariant until the last ca. 1500 yr, during which there is evidence of a period of warming followed by a subsequent cooling; it is speculated that these may correspond to the ‘Medieval Warm Period’ and to the ‘Little Ice Age’ respectively. The Morrone Birkwoods are noted today for their sub-Arctic vegetation and their rich flora, with the Arctic—Alpine and northern montane biogeographical elements especially well represented. The macrofossil record indicates that the flora has long had this general character, whilst both this and the pollen record indicate that the sub-Arctic character of the vegetation has most likely persisted since earliest Holocene times.

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