Paleoclimatic reconstructions for the south of Valdai Hills (European Russia) as paleo-analogs of possible regional vegetation changes under global warming

摘要

The possible response of forest ecosystems of south taiga at the south of Valdai Hills on projected future global warming was assessed using analysis of pollen, plant macrofossil and radiocarbon data from four profiles of buried organic sediments of the last interglacial and several cores from modern raised bogs and two small forest mires in the Central Forest State Natural Biosphere Reserve (CFSNBR; Twer region, Russia). The future pattern of climatic conditions for the period up to 2100 was derived using the data of A2, B1 and A1B emission scenarios calculated by the global climatic model ECHAM5-MPIOM (Roeckner E et al 2003 The Atmospheric General Circulation Model ECHAM 5. PART I: Model Description, Report 349 (Hamburg: Max-Planck Institute for Meteorology) p 127). The paleoclimatic reconstructions showed that the optimum of the Holocene (the Late Atlantic period, 4500–4800 14C?yr?BP) and the optimal phases of the last interglacial (Mikulino, Eemian, 130?000–115?000?yr BP) can be considered as possible analogs for projected climatic conditions of the middle and the end of the 21st century, respectively. The climate of the CFSNBR during the Holocene climatic optimum was characterized by higher winter (about 3?°C higher than at present) and summer temperatures (about 1?°C higher than present values). Precipitation was close to present values (about 600–800? mm?yr?1). Vegetation was represented by mixed coniferous and broad-leaved forest. In the warmest phases of the last interglacial the winter temperature was 5–8?°C higher than present values. The summer temperatures were also about 2–4?°C higher. Broad-leaved and hornbeam trees were the dominant tree species in vegetation cover.