english Ukrainian steppe: yesterday, today, tomorrow.

The steppe ecosystem of Eurasia, where Ukrainian steppe is situated, represents almost an unceasing belt from Hungary to Transbaikalia. Correct understanding of natural processes which take place in this ecosystem should contribute to the harmonization of interrelation between men who live here and nature.

Ukrainian steppes were formed by means of the influence of glacier (ice-flow) thousands years ago. Speaking more simply, the modern steppe belt was a wide boundary strip between huge masses of ice in the North and tropical forests in the South of the Northern hemisphere of our planet. Scientists call that ancient landscape a fenland steppe or a cold desert steppe. There were short-growing vegetation like in fenland, and harsh winds. Despite of a direct neighborhood of the huge masses of water the climate was dry and simultaneously cold. Because of glaciation the level of World Ocean was much lower than the contemporary level. Therefore it was no sea between the Crimea and the southern point of present-day Odessa region, i.e. near Danube delta. There were green pastures where mammoths fed on. Then they were substituted by buffaloes which, again, were crowded out by reindeer. Approximately 14 thousands year ago glaciers began to melt and retreat to the north. The period of melting took several thousands of years. The finish of glaciation is considered the breakout of the embankment which protected the soft Baltic lake from ocean salt water. Owing to the breakout the sweet-water Baltic lake turned into the salt Baltic sea. The glacier didn’t melt in winter and thin clay layers deposited on the lake bottom. Having calculated the clay layers of old lakes scientists have defined the exact date of that event – 8213 B.C. This date is an “official” date of the finish of the last Ice Age.

At that time soil formation process had began in the steppe zone and as a result of this the world-famous black top lands have arisen. The most of scientists considers loess and loess loams have direct glacial origin. They are a parent rock material which the black top lands were formed on. Under permanent influence of different temperatures, wind and water the rocks were abraded into finely divided materials that have become loess and loess loam.

Glaciation ceased in recent borders about 10 thousand years ago. Speaking more exactly it had borders which remained unchanged before the end of XX century as far as today we can see intensive melting of glacial remainders because of climate change. In those days, when the abundance of wild nature had reached its maximum and a human factor had no such a destructive influence as it takes place now, the period of intensive humus accumulation began in soil. Climate conditions in this geographic zone are characterized with some humidity deficiency. That is why plant residues could not decompose quickly and completely. Thus, there was a gradual process of organic matter accumulation or magnification. The interrelation of organic residues with calcium, which consists in loess and loess loam in large quantity, provided good granulometric (textural) qualities and structure.

Some scientists offer an alternative hypothesis of steppe descent. They consider the steppe was formed by means of wide-scale burning-out of forests. This could be done by ancient nomads for pasture expansion. It is difficult to prove or refute this hypothesis but we have to agree with the following fact. 5-6 thousand years ago the human factor became more and more influential for the existence of the steppe. Although the total destruction of Ukraine steppe ecosystem started 150 years ago only when a large-scale colonization began because of iron ore and coal exploitation. A high population density and the availability of rich black top lands provoked a total plowing up of the steppe.

Many years ago wild horses tarpans, steppe antelopes saigae and wolves run in steppes, eagles hovered under the sky, great bustards performed their awkward flights. It is a pity that time has passed off. The last tarpan died in 1918. Today the animal world of the steppe consists mainly of birds and invertebrate soil inhabitants. The weight of last ones in tillage layer (30 cm) amounts to 0.5 ton/ha in the Northern steppe and to 0.05 ton/ha in the Southern steppe. It is known the main decomposers of plant residues are fungi in the forest zone. However the main decomposers in the steppe are microorganisms and soil fauna. The key role in this process belongs to earthworms.

The recent steppe has a range of specific peculiarities. The quantity of precipitation (rainfalls) in the steppe belt of Ukraine varies from 350 mm in the Southern steppe (the Black sea region) to 500 in the Northern steppe near the belt of wooded steppe. An average annual temperature is about + 7 0C. A number of frostless season days is about 250 days. The basis of plant cover consists of grasses which can survive periodic droughts. Some scientists call the steppe a “forest upside-down” because the weight of steppe plant roots is much more than the weight of top plant parts. A large quantity of roots provides high soil conditioning. The quality of organic matter in many respects depends on initial plant substances. They are represented with soft grass tissues in the steppe that contain a low concentration of tanning substances, lignin and related to it mechanical structures which are abundant, for example, in woody tissues.

Unfortunately, Ukrainian steppe in its original appearance has persisted in a very small area. Today it is possible to meet the big representatives of steppe mammal species mainly in wildlife reserves and national parks. However, even small extant areas demonstrate the whole splendour, lordliness and brilliance of the steppe. The stipa or the feather grass together with other graminaceous plants dance in the wind like sea waves. Against the green background of them hundreds of blooming dicotyledonous species fill the steppe with bright rich colors: violet, blue, yellow, red… Besides multiplicity of colours you may feel in the steppe a saturated spicy odour of all the diversity of wild flora. Hundred species of birds fill the space with their ringing songs. What can be more beautiful than the summer steppe?!

It is a pity the most part of it has been transformed into the plough land. The plough land comprises about 56 % of the whole territory of Ukraine. Obviously the main basis for agriculture and plough lands is steppe belt of the country. Therefore the level of plowing up amounts to 90 % in some steppe regions. Having added to this index the area covered by buildings, industrial enterprises, agricultural protective afforestation, roads and other communications we can see that the area of steppe fragments is miserable. The typical steppe areas have remained near ravines, in hollows (small flat-bottom valleys) and slopes along rivers. Relatively large fragments of the steppe are situated in low-numbered natural reserves of the South-Eastern Ukraine.

The percentage of native forests in the steppe is low. If you read a great epic poem of Ancient Rus’ (i.e. Old-Ukrainian) literature “Lay of Igor’s Warfare” you may remember the following. When the king Igor run away from Polovets captivity and came back home nightly, he determined the allocation of rivers by means of woodpecker knock. Why? Because the most part of forests grew near rivers in XII century. Only oakeries were situated amid the steppe. Today there are many artificial forest plantations in the steppe. Obviously they are unnatural formations for the steppe belt but forest plantations are important for soil protection from erosion. They also are inhabitation for many wild animal species. However such a situation is only a device to compensate the absence of typical wild landscapes i.e. steppe areas. It proves once again that the main task in this territory is the enlargement of steppe areas but not forest ones.

Each natural wild ecosystem is unique, inimitable and important. It is a pity the recent trends of climatic changes endanger the further outlook of steppe ecosystem existence. Many scientists make pessimistic prognosis: if we don’t assume measures to correct the situation the most part of Ukraine steppe belt will become semidesert and certain parts will turn into desert in 50-70 years. Last years it is observed the deterioration of water regime in the steppe belt. The quantity of rainfalls decreases and the trend of their precipitation inequality and irregularity increases. As a result of it water deficiency takes place in the spring-summer period i.e. in the period of active plant growth and development. A big problem is disappearance of small rivers. One of the main causes of river perishing is a wide-scale construction of artificial dams and impoundments. It results in the shortage of water in rivers, slowing of their stream, and rotting of water in consequence of which the rivers disappear gradually. However, the main threat for the steppe is a wide-scale plowing up of the territory which causes the extermination of plant cover and soil degradation. In the beginning of XX century the percentage of humus in Ukrainian black top lands amounted to 9-9,5 %. The accumulation of such a humus quantity took thousands of years. However today, in the beginning of XXI century, the areas containing 4 % of humus are considered excellent. Anthropogenic activity has destroyed a half of humus stock in hundred years whereas its accumulation lasted 10 thousand years. The absence of permanent plant cover on the land surface is one of the main factors of desertification. Similar problems take place in China now not to speak about African countries.

A man considers the typical landscape which he has been accustomed since his childhood. For example, some old men perceive negatively situation when abandoned plough is overgrown with wild steppe plants because they see in it negligent attitude to land. Since their youth they have were accustomed to look at total plough lands created by Soviet agriculture. They consider it is correct, because they don’t take into account ecological factor. Ukrainian eco-philosopher F. Kanak have said on this subject: “Nobody feels the sadness for real, undisturbed landscape, which disappeared definitively after the outbreak of human activity in the sphere of ecosystem exploitation”. Therefore a new generation of people should understand the correct landscape is a natural wild landscape. Obviously, it is impossible to reject agriculture, but current situation of environment calls us to return the most part of the steppe ecosystem into wild state again. Otherwise we will have catastrophic consequence for nature and people.

Дата добавления: 2015-10-02