Some features of the Holocene insect faunas of northeastern Siberia

The composition of fossil insect faunas from northeastern Siberia changed significantly during the Pleistocene-Holocene transition. The Late Pleistocene insect fauna reflects tundra-steppe environments, and was dominated by xerophilic species. This fauna persisted regionally until ca 12,000 yr BP. A radical transformation of the environment occurred between 12,000 and 10,000 yr BP, marked by the permafrost degradation and invasion of tall shrubs and later trees into the higher latitudes. The early Holocene insect assemblages are dominated by mesophilic tundra species, but also include small number of more thermophilic species, which are currently restricted to the taiga zone. Tree-dependent species, however, were virtually absent. This early Holocene fauna has no modern analogue. The faunal assemblages indicate that the early Holocene climate was more humid than that of the Late Pleistocene, and warmer than today. Post-glacial sea level rise was in progress at that time, but the shoreline was still much further north, and the New Siberian Islands were still a part of the mainland. During the second-half of the Holocene, sea level continued to rise, and trees and tall shrubs retreated to the south. Regional ecosystems, including insect faunas, approached their modern compositions and boundaries. (c) 2006 Elsevier Ltd. All rights reserved.