Vegetation response to climatic oscillations during the last glacial–interglacial transition in northern Japan

A high-resolution (decade time-resolution) analysis of pollen from Ayameshitsugen Mire (750 m a.s.l.), Hokkaido, Japan, focused on vegetation response to climate change during the last glacial-interglacial transition. The succession analyzed covers the 14,050–8450 cal BP interval. Pollen records indicate that the area around the study site was occupied by boreal Betula-Picea-Abies forest during the late glacial period. Picea began to decrease at 11,600 cal BP and disappeared at 11,000 cal BP. Temperate forest elements began to increase about 100 years after the beginning of the decrease in Picea. Changing pollen assemblages over the early Holocene 11,600–8450 cal BP interval indicate that vegetation has not been in equilibrium with climate since the onset of Holocene conditions. Higher abundance of Ulmus and Juglans than at present characterizes early Holocene vegetation. A distinct cooling event coinciding with the Younger Dryas stade in the region only occurred 12,700–12,450 cal BP. The stade was less pronounced than in the North Atlantic region, and a gradual increase in Picea and Betula during the stade indicates gradual climatic amelioration in the region. Mire vegetation did not show a simultaneous response to the onset of Holocene warming.