Arguments for and against a Pleistocene tundra‐steppe¹

Comment from Editorial Board, Izvestiya Akademii Nauk, seriya geograficheskaya: This article contains irrefutable evidence indicating the considerable diversity of ecosystems existing in the peri‐glacial regions of Northeast Asia during the time of the last Pleistocene glaciation. Earlier prevailing concepts regarding the existence of an extensive uniform cover of cold tundra‐steppes thereby are refuted. The ideas advanced by the authors of this article are entirely consistent with the latest analytical arguments presented by P. M. Anderson and A. V. Lozhkin at the International Conference on Peripheral Regions of the Arctic held in Magadan in 1994. It is clarified, for example, that on the northern shores of the Sea of Okhotsk in the Late Pleistocene there were forests of larch and shrubby stone pine, whereas in Eastern Koryakia there were shrubby‐grassy tundras. Hardwood birch forests extended far to the north under improving climatic conditions during the Pleistocene‐Holocene transition period (11,000–9000 years B.P.). The sources of the present biotic diversity in the boreal belt evidently must be sought in the differentiation of the plant cover, which already had developed in the Late Pleistocene and is convincingly confirmed by the authors of this paper through the historical analysis of the flora on Chukotka.

However, the problem of a Pleistocene tundra‐steppe in Northern Eurasia is much broader than is outlined here. It is by no means restricted to Beringia, where because of the oceanic character of the climate the periglacial landscapes differed substantially from those in the intracontinental regions. In publishing this article, the editorial board recognizes that the debate over the Pleistocene tundra‐steppe retains its timeliness and by far not all the arguments advanced by the authors can be accepted as decisive either in a “pro”; or “con”; context.

Abstract

Arguments supporting the existence of a tundra‐steppe in northern Eurasia during the Pleistocene include three components—phytogeographic, palynological, and paleozoological—which logically support one another. However, the following arguments contradict the concept of a tundra‐steppe: (1) the determination of pollen and spores in “tundra‐steppe spectra”; is usually made at the level of the genus and family (rather than species), which cannot serve as an indication of the true nature of the vegetation; (2) taxons at the level of genus and family are a priori assumed to be steppe plants; (3) the relationship between spore‐pollen spectra and vegetation is not unambiguous; (4) paleodynamic processes in landscapes (especially redeposition processes), if taken into account at all, are done so only formally; (5) there are only a few xerophytic plant species in Beringia, but these are semizonal species; (6) most of the species constituting the associations, similar to steppe species, migrated to territories surrounding Beringia in the Holocene, and their migration is continuing even now; and (7) groupings in the high latitudes, like steppe groupings, have a negligible phytomass.

Notes

Comment from Editorial Board, Izvestiya Akademii Nauk, seriya geograficheskaya: This article contains irrefutable evidence indicating the considerable diversity of ecosystems existing in the peri‐glacial regions of Northeast Asia during the time of the last Pleistocene glaciation. Earlier prevailing concepts regarding the existence of an extensive uniform cover of cold tundra‐steppes thereby are refuted. The ideas advanced by the authors of this article are entirely consistent with the latest analytical arguments presented by P. M. Anderson and A. V. Lozhkin at the International Conference on Peripheral Regions of the Arctic held in Magadan in 1994. It is clarified, for example, that on the northern shores of the Sea of Okhotsk in the Late Pleistocene there were forests of larch and shrubby stone pine, whereas in Eastern Koryakia there were shrubby‐grassy tundras. Hardwood birch forests extended far to the north under improving climatic conditions during the Pleistocene‐Holocene transition period (11,000–9000 years B.P.). The sources of the present biotic diversity in the boreal belt evidently must be sought in the differentiation of the plant cover, which already had developed in the Late Pleistocene and is convincingly confirmed by the authors of this paper through the historical analysis of the flora on Chukotka.

However, the problem of a Pleistocene tundra‐steppe in Northern Eurasia is much broader than is outlined here. It is by no means restricted to Beringia, where because of the oceanic character of the climate the periglacial landscapes differed substantially from those in the intracontinental regions. In publishing this article, the editorial board recognizes that the debate over the Pleistocene tundra‐steppe retains its timeliness and by far not all the arguments advanced by the authors can be accepted as decisive either in a “pro”; or “con”; context.