Monday, April 30, 2012, 12:00PM - 1:00PM
Institute for Ecosystem Research, Christian-Albrechts University
ARC room 620
The relationship between vegetation dynamics, climatic variability and early human activity during the fourth millennium BC was reconstructed from high-resolution pollen and geochemistry records obtained from two small lakes and a fen site located along an altitude gradient in County Sligo, Ireland. The proxy records suggest the existence of a largely closed woodland cover during the late Mesolithic, with some minor human disturbance occurring prior to 4000 BC. At all three sites, a first significant change in the woodland composition was associated with the decline in the local elm populations during the Early Neolithic. This decrease coincided with a phase of a general climatic amelioration and a subsequent increase in anthropogenic activities. The favorable climatic conditions, which led to particularly low water tables at all sites, prevailed until at least 3700 BC. Human impact on the landscape was most pronounced during this period. The palynological evidence indicates that wheat cultivation was practiced in the catchment area of the lake located at lowest altitude. The onset of wetter and cooler conditions after 3700 BC resulted in a notable decline in human impact and woodland recovery. The Mid-Neolithic was characterized by a series of alternating climatic conditions. Periods of substantial rainfall prevailed between 3700-3400 BC. A subsequent interval of climatic amelioration centering on 3400 BC facilitated a revival of human activity in the landscape on a smaller scale. A further wet period occurred between 3350-3250 BC, resulting in the abandonment of the area and full woodland recovery. The pollen and geochemistry data suggest that the Late Neolithic was marked by a period of ameliorated conditions between 3080-3030 BC that was followed by episodes of high rainfall at 3030 BC and 2920 BC. The present study shows that the timing of the inferred climatic shifts during the fourth millennium BC is in agreement with those of moisture/precipitation and temperature reconstructions from northern and western Europe. The high-frequency climate variability appears to have influenced the human development during the Irish Neolithic. It is further shown that the inferred climatic shifts correspond to variations in solar activity, suggesting a solar forcing on climate during that time.