Coleopteran evidence for a mosaic of environments at high altitude in the eastern Pyrenees, France, during the climatic transition between the Allerod and Younger Dryas

Late-glacial environmental and climatic implications are inferred from an insect fauna from organic sediments infilling a palaeochannel on the banks of the River Tet, eastern Pyrenees, France. A pine cone in association with the insect fauna has been radiocarbon dated to 10 920 +/- 60 yr BP, namely close to the Allerod - Younger Dryas boundary. Two distinct insect associations appear to be recognisable here. One is an assemblage typical of the high altitude forest and a second is characteristic of an alpine grassland. The close coexistence of these two assemblages is attributed to the climatic cooling towards the start of the Younger Dryas Stadial, when the forest cover broke up into remnant patches interspersed by alpine grassland. It is suggested that in a region of such high relief a mosaic of habitats may have been caused by patchy differences in insolation aspect, especially during a period of climatic deterioration. Copyright (C) 1999 John Wiley & Sons, Ltd.