by Pavel KRESTOV, Dr. Sc. (Biol.), Biological and Pedological Institute, the Far Eastern Branch of the Russian Academy of Sciences (Vladivostok)
Man is prone to look into the future, and numerous scenarios of global climatic warming or cooling draw by no means an optimistic picture of the natural environment in the centuries to come. In the meantime, there have always been organisms capable of surviving in the most severe periods of global history, and therefore their record is of great value. Despite the existing climate, plant communities and whole ecosystems keep developing-those quite common some time ago and now using unique properties of their habitats or refugia (refuges). Plants and animals inhabiting such areas have retained special adaptation mechanisms not manifest under present-day conditions. Will their hour come?
ICE AGE: A "WHITE SILENCE"?
Vast glaciations of the Late Pleistocene on the European and North American continents were associated with climatic conditions fatal to life. During the Pleistocene maximum (18-20,000 years ago) an ice sheet up to 3,000 m thick covered almost the whole territory of Canada, thousands of kilometers of "white silence"... Only rocks of the Coast Range cut across a dead expanses in a strip of the far west of North America connecting the Cordilleras, covered with forest vegetation exuberant for that period, with "frozen" but not ice-bound North Alaska, Chukotka and now extinct Beringia.
At the same time extremely severe climatic conditions in Asia made rank vegetation growth virtually impossible, as proved by polynological spectra and remains of insects home to cold desert ecosystems. The obtained paleodata gave birth to a special term for the dominant native biome, i.e. "tundra steppe". However, Pleistocene megafauna findings broke harmony of the concept. Many a finding made it possible to suggest that mammoths, wooly rhinoceros, bisons, horses and beasts of prey associated with them were n ... Read more