The location of the Eurasian steppe biome coincides with the zone of high atmospheric
pressure and, despite the differences in climates of the landlocked steppes and those
located closer to the coast (e.g., southern Moldova receives about 410 mm of precipitation
per annum while Tuva has only about 215 mm), moisture supply is insufficient across the
biome. Evaporation exceeds precipitation by a factor of 2-3. Typical are the distinct June
(July-August in the Dahurian steppes) maximum in precipitation and its high interannual
variability. An important climatic feature is the small thickness of snow cover and the
redistribution of snow by wind. Snow is often blown off the watersheds and accumulates in
topographic depressions, shrublands, and woodlands, which causes strong spatial
differences in soil climates. The temperature gradient changes eastwards as a result of
increasing continentality. The mean annual temperatures change from approximately 9°C in
Moldova to about -6°C in Tuva and the mean annual temperature amplitude increases from
27°C to 53°C. Figure 11.2 illustrates the spatial variations in the mean January
temperatures and the duration of the frost-free period in the southern steppes.
Fig. 11.2 Mean January temperatures and average continuation of the
frost-free period in the southern steppes
All biotic components of steppes are closely controlled by climate and change from west
to east in response to the increasing continentality. This is expressed in both the
changing structure and floristic composition of vegetation (the replacement of the
European species by the Kazakh and then Mongolian species) and in the changing
productivity of ecosystems, the ratio between the above ground and below ground biomass,
and the thickness of the humus horizon (Mordkovich, 1982).
