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Biomes and Regions of Northern Eurasia

Steppe and Forest-steppe

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Introduction: Main Features and Definitions

Treeless areas, termed steppes, occupy vast areas between boreal forests and temperate deserts in Eurasia. There are many definitions of steppes. For example, Allan (1946) provides fifty-four definitions of this term. Stamp and Clark (1979) define steppes as 'mid-latitude areas dominated by herbaceous vegetation and termed locally steppes, prairies, pampas, high veldts, downland, etc.' A more precise definition of steppes is offered by geobotanists who define it as a type of vegetation, represented by communities of drought- and frost-tolerant perennial herbaceous species with a dominance of sedges (Poaceae) and, less commonly, galingales (Cyperaceae) and bulbs (Alliaceae).

The main features of the temperate steppes are continental climate, the absence of trees on watersheds, and the predominance of sedges on black and chestnut soils. Steppes extend as a continuous belt from the plains adjacent to the Black Sea to Western Siberia and become fragmented east of the Altay because of the mountainous character of the terrain (Figure 11.1).

Fig. 11.1 Location of steppe, forest-steppe, and semi-desert zones

Steppe is the main biome located between the humid landscapes of the boreal forests and the arid environments of deserts. The forest-steppe ecotone occurs between steppes and forests in the north while semi-deserts form a transition from steppes to the desert environments. Forest-steppes have a more humid climate than steppes and in their natural condition represent a mosaic of meadow steppe vegetation and woodlands, ft is the forest-steppe that serves as a demarcation line between humid and arid environments and here annual precipitation and evaporation are approximately equal. The forest-steppe extends as an uninterrupted zone from the Carpathian foothills to the Altay and, similar to the steppe, becomes fragmented further east. Semi-deserts are distinguished by a more arid climate than the steppes and the domination of the communities by species of the genus Artemisia, and sedges. This zone extends from the lower course of the Volga to the upper course of the frtysh and occupies a considerable part of central Kazakhstan.

Steppes and forest-steppes have been transformed by human activities more than any other part of Northern Eurasia. In the European part, over 60 per cent of the steppe territory is now occupied by arable land and in the forest-steppe natural woodlands have mostly been cleared. It is fair to say that, with the exception of rather small protected areas, the biogeography of the European steppes and forest-steppes is now cultural rather than natural. The development of the Asiatic steppes began later and their transformation has not gone as far as in the western part of the region. However, in many regions original ecosystems have been transformed by farming and in the late 1950s vast areas in Southern Siberia and northern Kazakhstan were turned into arable fields in the course of one of the largest Soviet undertakings ever, the Virgin Land project. Because of it, this chapter emphasizes the transformation of the environment and adaptation of various components of the environment to human pressure, rather than approaching the steppes and forest-steppes of Northern Eurasia from the perspective of traditional biogeography.

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