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Biomes and Regions of Northern Eurasia

Steppe and Forest-steppe

<<< Anthropogenic Transformation of Steppe and Forest-steppe | Biomes & Regions Index | The Future of the Steppe >>>

Issues and Problems of Development

Overexpansion of Arable Agriculture

Although the modern structure of land use is a result of the long history of development, the greatest influence has been exerted by certain socioeconomic factors of the Soviet period of which state landownership, establishment of large-scale state farms, housing policies, and the development of irrigation are the most important. Perhaps the most drastic transformation of the steppe landscape occurred between 1954 and 1960 when in the course of the Virgin Land project 418000 km2 of virgin steppe was brought into agricultural production in the Transvolga region, Southern Siberia, and northern Kazakhstan and 3 million people migrated into the area to provide labour. In order to meet the nation's food need quickly, large-scale fields were ploughed and planted using heavy machinery. Massive overexploitation of land occurred as not only the best soils but also soils ill-suited for cultivation (sandy, stony, and saline soils) were developed. In the following years, national yields of wheat increased and in this sense the project achieved success, albeit more limited than was expected. The effects on the steppe environment, however, were adverse. The frequency of wind erosion and dust storms increased dramatically, the runoff in small rivers declined by 40-50 per cent and productivity of pastures and hayfields in the adjacent areas of the Transvolga region decreased by a factor of 2.5-3 (Chibilyov, 1992).

Large-scale production undoubtedly proved damaging and the optimization of structure of arable land is required. Measures aimed at this should involve: introduction of the optimal sizes of arable and irrigated fields; usage of lands best suited for the given agricultural practice; diversification and finding the optimal combination of various types of agricultural activities; and development of agricultural ecosystems which can easily adjust to the natural bioclimatic conditions without exhausting the agricultural potential of the landscape. The single most important measure should be the reduction in arable land and particularly the withdrawal of marginal lands from cultivation. In the past, cultivation of stony, gravely, and saline soils and already eroded slopes led to widespread aridization (desertification).

Aridization is particularly an issue in the southern steppe and semi-deserts. It is manifested in the intensive development of erosion, decline in the contents of organic matter, reduction of the above ground phytomass, and the changing radiation budgets of soils. A distinct indicator of aridization is the northward advance of the distribution areas of semi-desert and southern steppe insects (e.g., the locust), birds (e.g., the Demoiselle crane), and plants such as Festuca and Stipa kssingiana.

The Grazing Capacity of Pastures

Unanimously researchers agree that steppe ecosystems have formed under the influence of grazing livestock. Grazing has always had both beneficial and detrimental effects on pastures. In intensively grazed pastures, degrading effects of overgrazing occur which, notwithstanding what original types of vegetation association dominated, include a reduction in number of species, mechanical disturbance of soils, and invasion of unproductive species such as ephemerals, emphemeroids, and plants adapted to high concentrations of nitrogen (particularly perennial weeds).

The effects of overgrazing on ecosystems have been a focus of research in Russia since the beginning of the 20th century (Vysotsky, 1915; Pachosky, 1917; Alekhin, 1934; Evseev, 1954; Ivanov, 1958; Gorchakovsky and Ryabinina, 1984; Chibilyov, 1992). However, it is difficult to correlate these results and assess the issue for the whole of Northern Eurasia because of the vastness of the area and the different timing of research. Thus in the 1950s, Ivanov (1958) distinguished five stages of pasture degradation in western Kazakhstan, showing that the productivity of pastures declined from 1.35 kg m-2 (undisturbed pastures) to 0.12 kg m-2 (permanent damage). Similar data were obtained later by Gorchakovsky and Ryabinina (1984) for the southern Urals. They distinguished four stages of pasture degradation and reported declines in productivity from 1.4 kg m-2 to 0.3-0.2 kg m2. The detrimental effects of overgrazing are notoriously persistent and it takes a considerable length of time for pastures to recover.

Steppes as pastures

Plate 11.3 Steppes as pastures (photo: A. Chibilyov).

The timing of grazing is particularly important for steppe ecosystems. Especially damaging is grazing in spring, when soils are still wet after snow melt. Mechanical pressure of hooves on soil disturbs it, causes compaction and damages plants. Soil crusting, rapid loss of moisture from soil and loss of valuable fodder species follow. Early grazing is widely practised in the southern steppes of the Volga region and southern Urals because of the shortage of forage in winter.

A number of measures have been proposed to use pastures in a more sustainable way and to restore those that are damaged. These include: evaluation of pasture capacities and compliance with the established norms of grazing; improving winter forage supply and prohibition of early spring grazing; introduction of recovery periods for pastures instead of using them by different livestock; and improving productivity of pastures through mulching, application of fertilizers, and artificial sowing of sedges and leguminous plants. The introduction of pasture management began in the Transvolga region, Southern Siberia and northern Kazakhstan in the 1980s when livestock numbers peaked. After 1992, a decline in stock occurred. In some regions of Kazakhstan stock numbers decreased by a factor of 2.5-3 and in the Transvolga and southern Urals by a factor of 1.5-1.8. The area of arable land was also reduced, encouraging the formation of fallow soils which are often used for grazing. However adverse the economic effects of agricultural decline were, pastures received a much needed recovery period and the problem of overgrazing has become less pressing.

Irrigation

Although the most intensive development of irrigation occurred in the desert and semi-desert zones, and particularly in Central Asia, steppe also accommodates a number of large projects. The most unfortunate aspect of irrigation development is that little distinction was made between irrigating desert and steppe soils. Norms of water supply, originally proposed for the arid regions, were introduced ignoring the fact that climate and weather in steppes are different and, unlike in deserts, dry and wet years and spells alternate and so does the moisture contents of soils. Similar to the infamous irrigation projects of Central Asia, irrigation practices used in the steppe are rudimentary with canals unlined, pipes leaking, and return flows not collected properly. The attempt to supply water to chernozems has had a very damaging effect because natural to these soils are a seasonal moisture deficit and a succession of wet and dry years. Instead of improving the quality of chernozems, irrigation has caused a substantial loss of organic matter, a rapid rise of the ground water table, waterlogging, salinization, and the development of erosion. In almost every chernozem region where irrigation was practised, there are examples of abandoned fields that originally had a high quality but then became degraded because of irrigation. By 1987, in Russia's steppes alone, 606000 hectares of arable chernozems had been withdrawn from agricultural use (Egorov, 1989). Particularly damaged were soils in the Rostov and Saratov regions. The 10-15 year history of irrigation of chernozems in the Northern Caucasus has led to a twofold increase of salts in the uppermost metre of the soil (Shipunov, 1988).

Researchers, concerned with the effects of irrigation on chernozems, suggest that irrigation practices in the steppe regions should change and in future be based on the following principles: irrigation should be limited to periods of droughts and norms of water supply should be adjusted to weather conditions; water losses to soil should be reduced by lining canals and furrows; and the ground water table should be maintained at a depth of 5-6 m (Rozanov, 1983). However, the best solution may be to keep the irrigation of chernozems to a minimum while introducing alternative methods to improve agricultural productivity (Chibilyov, 1992).

Agroforestry

The naturally low woody cover of steppes and the deforestation by humans in the past influenced scientists and agronomists to consider reforestation and agroforestry as measures to improve the climate and water balance in the steppe and forest-steppe. This work was pioneered at the end of the 19th century by Vasily Dokuchaev. In 1892, working for the State Forestry Department, he established three experimental plots each covering 50 km2 in the Voronezh, Kharkov, and Yekaterinoslav (now Dnipropetrovsk) provinces with the purpose of developing agromelioration and agroforestry (Dokuchaev, 1895). The major idea was that belts of trees (termed shelter-belts) planted around arable fields improve moisture retention by soils and protect fields from dry winds which are one of the major climatic hazards in the region. Later, in the 1920s, following severe droughts in the southern East European plain, the Russian government adopted a series of measures aimed at combating the adverse effects of droughts, emphasizing once again the importance of reforestation and agroforestry. By 1941, about 5000 km2 of shelter belts and protective woodlands had been established across the FSU and by 1953 another 23000 km2 had been planted. Today, these woodlands have the same ecological, cultural, and recreational functions as natural woodlands. They have also proved helpful in the improvement of microclimate, productivity of agricultural ecosystems (through a more favourable climate and by harbouring birds who feed on pests and weed seeds), and regeneration of damaged landscapes. By providing habitats for animals and birds, they improve biological diversity of the steppe and forest-steppe.

Although agroforestry proved extremely successful in the steppe and forest-steppe regions, the completed agroforestry systems are still lacking in the steppes of Russia and even more so in the steppes of Kazakhstan. Even in the Kamennaya Steppe in the Voronezh region, where one of the Dokuchaev's experimental plots is located, shelterbelts and protective forests around fields occupy less than 1 per cent of all arable land, although the area required is 2.2-2.5 per cent. Only 11 per cent of the shelterbelts needed to prevent gullies from expansion has been established (Shipunov, 1988). Essential to the agroforestry practice is its complete implementation so that it can function as a landscape system in which a balance between various types of woody cover and arable land is achieved (Chibilyov, 1992).

Restoration of Fauna

Before the advent of arable agriculture, steppe and forest-steppe biomes had a rich fauna. According to Mordkovich (1982), the stock number of large (such as marmot) and larger mammals exceeded one billion. There were also a few hundred million large birds. The potential of steppe vertebrates to adapt to the transformation of habitats, caused by humans, varies. Crops provide some species (e.g., ground squirrel, common hamster, rook) with additional food supplies and their populations have increased in marginal lands and pastures. Shelterbelts and protective woodlands provide habitats for other species (elk, roe deer, hawk, woodpecker) who migrate to the steppe from the north. However, agricultural development has had a detrimental effect on most species. Due to the widespread loss of habitat, the distribution areas of many species have diminished, population has been depleted and locally some species (great bustard, tawny eagle) have become extinct.

There are, however, signs that that there is still a potential for the restoration, at least partial, of fauna in the forest-steppe and steppe. Research, conducted in northern Kazakhstan and the southern Urals in the 1970s — l980s has shown that across large areas marmots have begun to adapt to the transformed habitats (Dezhkin, 1987 a, b; Bibikov, 1989). In the Karaganda region of Kazakhstan, the average population density of marmots within the 300 m of an arable field varies between 17 and 21 animals per km2 compared to 25 in the pristine steppe (Kapitonov, 1987) while in the Orenburg region its population in close proximity to fields reaches 28-35 (Chibilyov, 1992). Since the early 1980s, the population of the little bustard has been increasing in the steppes of Transvolga and the Urals while an increase in the population of the great bustard has occurred in the Transvolga areas of the Saratov region (Khrustov et. al., 1997). Forestation and reforestation, construction of reservoirs, and diversification of land use in comparison with the previous decades reduce pressure on the steppe inhabitants and provide at least some opportunity for the restoration of the steppe and forest-steppe fauna.

Nature reserves and research institutions are also concerned with the restoration of biological diversity. There has been much success in the restoration of the stock of saiga. The population of the Asiatic wild ass (Kulan), the restoration of which began in 1941 in the Badkhyzsky nature reserve in southern Turkmenistan, has now reached 2000 individuals (Chibilyov, 1990). Attempts are now being made to restore the population of auroch and the wild horse.

<<< Anthropogenic Transformation of Steppe and Forest-steppe | Biomes & Regions Index | The Future of the Steppe >>>

 

 


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