Pollen analyses and radiocarbon dates from Zhukovskoye peat mire (56°20′N, 84°50′E), situated in the south-eastern part of the boreal forest (taiga) zone of West Siberia, suggest that climatic oscillations of the Lateglacial were well expressed in the region. These events are tentatively correlated with the Alleröd warming and the Younger Dryas cooling in Europe. In the Alleröd, complex vegetation combined larch copses with birch and spruce in wetter places with dry steppe communities dominated by Artemisia and Poaceae. The climate was cool and continental, with moderately warm summers. Due to the onset of colder and drier climate in the Younger Dryas the wooded areas were reduced, while xerophile herbaceous communities with periglacial steppe elements expanded. Following the warming in the Early Holocene, woody vegetation was established in the area. At the early stage the woods were dominated by birch, larch and Scots pine. Later an increase in moisture caused formation of Picea taiga forest with Abies and Pinus sibirica. In the relatively warm and humid climate the process of mire development spread over a major part of West Siberia. Comparison with the published data on other sites in West Siberian plain shows that the warmest conditions existed in the region approximately 6–5 ka BP (non-calibrated 14C age). The warming is indicated by spread of more heat-demanding forest communities in the taiga zone and by a shift of the forest/tundra boundary to the north. Cooling in the late Holocene caused a decline of the relatively thermophile species in the forests and a retreat of the northern tree line to the south. Development of the raised peat bogs in the southern taiga sub-zone of West Siberia reflected in pollen profiles shows that this cooling continued in Subatlantic time.

Phytomass of terrestrial vegetation and soil humus are considered to be the most important sinks of carbon, and therefore their changes during glacial–interglacial macrocycle may influence considerably the carbon balance. Spatial reconstructions of paleovegetation and paleosols at the key intervals within the macrocycle, namely the Mikulino (Eemian) Interglacial ∼125ka BP, the Last Glacial Maximum 20–18ka BP, and the Holocene optimum ∼5.5ka BP made it possible to estimate quantitatively the phytomass and soil humus carbon in Northern Eurasia (within the limits of the former Soviet Union). With the phytomass in modern (potential) vegetation taken as 100%, phytomass accumulated in vegetation which existed in Northern Eurasia 125, 18–20 and 5.5ka BP amounts to 150%, 27% and 129%, respectively. The estimated carbon storage in soil humus for the same intervals is 149.2%, 23% and 128.8% of the present-day value. The values are similar to those previously calculated for the East European Plain except for LGM, where phytomass calculated for the whole territory of Northern Eurasia is relatively higher than that calculated for the East European Plain (27% and 6%). The same tendency is seen in the carbon storage in paleosols dated to the LGM 23 and 15% respectively. The difference in relative phytomass and carbon storage calculated for Eastern Europe and for Northern Eurasia may be attributed to the fact that degradation of forest and steppe vegetation was less pronounced in continental Siberia than in Eastern Europe.

Velichko, A. A., Novenko, E. Y., Pisareva, V. V., Zelikson, E. M., Boettger, T. & Junge, F. W. 2005 (May): Vegetation and climate changes during the Eemian interglacial in Central and Eastern Europe: comparative analysis of pollen data. Boreas, Vol. 34, pp. 207–219. Oslo. ISSN 0300–9483. The article discusses pollen data from Central and Eastern Europe and provides insight into the climate and vegetation dynamics throughout the Eemian interglacial (including preceding and succeeding transitional phases). Three sections with high resolution pollen records are presented. Comparison of the data indicates that the range of climatic and environmental changes increased from west to east, whereas the main phases of vegetation development appear to have been similar throughout the latitudinal belt. At the interglacial optimum, the vegetation in both Central and Eastern Europe was essentially homogeneous. An abrupt change marks the Saalian/Eemian boundary (transition from OIS 6 to OIS 5e), where environmental fluctuations were similar to those detected at the transition from the Weichselian to the Holocene (Allerød and Dryas 3). Transition from the Eemian to the Weichselian was gradual in the western part of the transect, with forest persisting. In the east, fluctuations of climate and vegetation were more dramatic; forest deteriorated and was replaced by cold open landscapes.

Typical mammoth inhabited the East European Plain during the second half of the Late Pleistocene glaciation. Under conditions of extremely arid climate, periglacial, mostly open landscapes formed a vast hyperzone (cryohyperzone) that occupied the place of the modern tundra, forest and steppe zones. To assess the available foodstuffs for mammoth provision, data concerning productivity and nutritive value of modern herb and grass vegetation that may be considered as more or less close analogues of periglacial communities can be used. The central part of the Late Pleistocene periglacial hyperzone was most favorable for mammoths. Those regions were well endowed with water (in large rivers, as well as snow and ice) and presented the richest fodder base, because trees and bushes persisted in valleys, while higher watersheds were occupied by periglacial steppe.Climate warming and consequent degradation of permafrost resulted in instability of the land surface, thermokarst, and expansion of wetlands. The snow thickness increased due to more abundant snowfall in winter and made grazing difficult for mammoths. The first interstadial warming affected the less hardy early mammoths, while the progressive warming towards the Holocene appeared fatal to the typical mammoth. (C) 2004 Elsevier Ltd and INQUA. All rights reserved.

The phytomass (the biomass of terrestrial vegetation) is one of the main reservoirs of carbon, as carbon makes up approximately 0.45 of the phytomass by weight [Ajtay, G.L., Ketner, P., Duvigneaud, P., 1979. Terrestrial primary production and phytomass. In: Bolin, B., Degens, E.T., Kempe, S., Ketner, P. (Eds.), The Global Carbon Cycle, SCOPE 13, Wiley, Chichester, pp. 123–181.]. During the glacial–interglacial climatic rhythm both composition and geographical distribution of vegetation over Northern Eurasia have been repeatedly subjected to major changes, accompanied by corresponding changes of phytomass and carbon storage. Of special interest are three key intervals within the last 125,000 years: the Mikulino (Eem) Interglacial optimum, about 125 ka BP; the Last Glacial maximum, 18–20 ka BP and the Holocene optimum, 5.5–6 ka BP. These intervals correspond to the extreme states of the environment. Vegetation which existed in Northern Eurasia 125, 18–20 and 5.5–6 ka BP, accumulated 377.1 Gt, 66.1 Gt and 292.1 Gt of phytomass, which corresponds to 169.7 Gt, 29.9 Gt and 131.4 Gt of carbon, respectively. Compared to present-day carbon storage in the phytomass of potential vegetation (taken as 100%), these values are 155%, 27% and 120%, respectively.

The authors describe the evolution of a new field in cartography—the substantive basis of which is the preparation of a series of spatial reconstructions (climate, landscape components) of the past on the basis of principles of comprehensive mapping of contemporary geosystems. The paper investigates how such an approach may be used to assess the present status of landscapes from the perspective of their general evolution and assist in the formulation of long-range predictions. Translated by Edward Torrey, Alexandria, VA from: Izvestiya Akademii Nauk, seriya geograficheskaya, 1998, No. 5, pp. 30-43.

The phytomass stored in terrestrial vegetation at 5.5, 18 and 125 Ka BP, representing the environmental extremes of the Late Quaternary, was estimated for the Russian Plain, excluding the northern coast and adjacent piedmont. The estimates are based on paleovegetation maps by Grichuk [Grichuk, V.P., 1982. Rastitel `nost' Evropy v pozdnem pleistotsene. In: Gerasimov, I.P., Velichko, A.A. (Eds.), Paleogeografiya Evropy za Posledniye sto Tysyach Let. Nauka, Moscow, pp. 92–109, (in Russian).] for Eemian optimum, by Velichko and Isayeva [World Atlas of Resources and Environment, 1996. Lionty, H.A. (Ed.). Institute of Geography of RAS, Moscow, Vienna.] for the Late Glacial Maximum, and by Khotinskiy [Khotinskiy, N.A., 1984. Holocene vegetational history. In: Velichko, A.A. (Ed.), Late Quaternary Environments of the Soviet Union. Univ. of Minnesota Press, Minneapolis, pp. 179–200.] for the Late Atlantic, together with analysis of the ecological–coenotic connections of plants and their modern areas. Vegetation on the East-European Plain at 125, 18 and 5.5 Ka BP contained 81.0, 3.1 and 61.4 million kilotons of phytomass, which represents 36.5, 1.4 and 27.6 Gt of carbon. The phytomass of terrestrial plants thus represents an important sink of carbon. Its marked changes make it an important part of the carbon balance during the Pleistocene and the Holocene.

The concentration of methane in the atmosphere has varied considerably during the last 125,000 years. Boreal wetlands represent one of the main sources of methane emissions into the atmosphere, the rate of which is largely controlled by climate. Changes in climate (mainly in the duration of the frost-free period) and in the extent of wetlands presumably caused variations in the methane production from boreal ecosystems. We chose Northern Eurasia to estimate both climatic changes and the area of methane-producing ecosystems, as it plays a leading role in methane emission. Palaeobotanic and palaeocryological data were used for the reconstruction. The two most recent warm stages: the Holocene Optimum (5500–6000 years BP) and the Last Interglacial Optimum (ca. 125,000 years BP) were studied. During these warm periods, both an area of tundra and the proportion of the wetlands within the boreal forest zone were considerably reduced. On the other hand, a longer frost-free period and higher precipitation would have caused higher methane production. The precipitation rise was apparently in part compensated by an increase in potential evaporation due to higher summer temperatures. Compared to methane emissions of about 9×106 t per year from modern forests of Northern Eurasia, emissions amounted to 86 and 44% of modern values for the region during the Holocene Optimum and Last Interglacial Optimum respectively. Under the greenhouse warming expected early in the 21st century, the climatic conditions may lead to a considerable increase of methane emission.

Tundra vegetation during the Alleröd optimum was limited to the fringe of the Scandinavian ice sheet and the Kola Peninsula. In contrast, forest-tundra vegetation assemblages, including birch, pine and spruce, were much more extensive, reaching the Arctic Ocean coastline, in northeastern Europe. Pine, birch and mixed pine-birch forests flanked the southern periphery of spruce forests in the Russian Plain, Belarus and the eastern Baltic states. Mixed deciduous forest vegetation extended at least to the Rhodopes Mountains of Bulgaria. Vegetation assemblages indicated by pollen preserved in Alleröd deposits have no direct analogues elsewhere in the Quaternary climato-stratigraphic record, resulting from the short duration of the Alleröd event. Existing plant communities responded to the Alleröd climate by changes in areal distribution and relative porportions of species, and long-range migrations were not significant. During the Valdai Late Glacial Maximum, periglacial tundra communities dominated the margins of the glaciers, with periglacial-steppe assemblages characterizing the regions to the south.