Climatic control of blanket mire development at Kentra Moss, north-west Scotland

1 Four peat cores were collected from Kentra Moss, north-west Scotland, and analysed for botanical macrofossils and peat humification. The pollen record was used as a template for the identification of synchronous levels between cores. 2 A non-random pattern of change in bryophyte macrofossils and humification was simultaneous between all four cores. Stratigraphic changes occurred independently of human land-use and were best interpreted as palaeoclimatic events. Remains of Racomitrium lanuginosum and Sphagnum papillosum, in conjunction with changes in peat humification, provided the clearest indication of past increases in climatic wetness ('wetshifts') to impact upon mire hydrology and ecology. 3 Eight wetshifts were identified and radiocarbon-dated, beginning at c. 3250, 2550, 2150, 1400, 1150, 875, 600 and 325 calibrated years BP (cal. BP). Seven of these wetshifts match closely with palaeoclimatic events from a range of mires previously examined in Britain and Ireland. We suggest that blanket mires may provide the best source of decade- to century-scale palaeoclimatic information in oceanic north-west Europe. 4 The proxy-climatic evidence indicates that: (i) the extinction of Sphagnum imbricatum at Kentra Moss (at c. 1400 cal. BP) was caused by an increase in climatic and mire surface wetness, when it was replaced first by Racomitrium lanuginosum and then by Sphagnum papillosum; and (ii) that increased climatic wetness and human land-use were responsible for the shift from an early minerotrophic peatland to ombrotrophic blanket mire at c. 4070 cal. BP. 5 Given the evidence for a prevailing climatic effect on the development of Kentra Moss, the effect of human-induced global warming on Britain's blanket mire resource will probably be significant. British blanket mires have international conservation status, and future changes in their ecology will challenge conservationists, academics and politicians.