Man has wrought many changes in the steppe region. In the first place he has entered into the struggle between the woods and the steppe in opposition to the woods. The ancient Ukrainians of the Kiev state rooted out great areas of forest and reclaimed them for civilization. On the other hand, the nomad tribes, roaming the steppes ever since man can remember, repeatedly destroyed forests with fire, in order to obtain good pasture for their herds and to break down the best defense of the agricultural Ukrainian population. In the 16th Century began the deforestation of the transition zone thru the progressing colonization movement of the Ukrainians, under the protection of the Cossack organization. But even in the 18th Century there were still great forests in the transition zone, which have since entirely disappeared. The intensive colonization movement of the 19th Century put an end to them. At the same time the hand of man attacked the steppe formation. Today only very small parcels of steppe are in their original condition. The steppe grasses have yielded place to an increasingly intensive cultivation of grain grasses; the place of the natural steppe has been usurped by the cultivated steppe, with its waving fields of grain and inevitable dreary stubble fields. With the progressive destruction of forests this cultivated steppe of man's fields constantly moves toward the north and west of the Ukraine, favoring the accompanying migration of the steppe-plants and steppe animals into Central Europe.
Entirely independent is the position of the Ukrainian flora in the southern slope of the Yaila and the Caucasus. They belong really to the Mediterranean Sea region. The mild climate here has matured a flora of an entirely southern type, with many evergreen trees and shrubs peculiar to the Mediterranean region. Yet the vegetation of this district can only be considered as the advance guard of the real Mediterranean vegetation, for the representatives of the northern flora by far predominate over the southern species of plants, particularly in the forests which develop in higher altitudes.
Besides the just discussed plant-geographical regions and zones of the plain, the Ukraine has three mountain regions — the Carpathian, the Crimean and the Caucasian.
The foot of the Carpathians is covered by mixed and leafy forests. White beech, birch, linden, aspen and pine comprise these forests. At one time the oak predominated here, as it still does on the southern slope of the mountain range. On higher ridges of the Low and High Beskid, mixed forests of beech and fir are found. At the upper tree limit of the High Beskid the beech appears almost exclusively in forest formation. The trees become constantly smaller and more gnarled, and at a height of 1000 m. we meet only beech brush. On the southern side of the mountain range pure beech woods prevail.
In the Gorgani we soon distinguish two forest zones.
The lower one has principally beech woods, with an admixture of firs and maples; the upper one consists almost entirely of fir woods. Their upper limit usually lies at a height of from 1500 to 1600 m., but the zekoti (seas of sandstone boulders), which cover all the higher peaks and ridges, reduce the upper tree limit a great deal in some places.
In the Chornohory, a similar division of the forest zone prevails. Oak forests, with thick underbrush, cover the foot of the range on both slopes. Above the oak woods lies the zone of mixed forests, in which white and red beech, birch, ash, maple and firs predominate. Above the height of 1300 m. lies the upper tree zone, which is made up of stocks of fir entirely. The upper tree limit lies at a height of 1700 m. The milder climate of the Chornohory matures a much more luxurious and a richer vegetation than in other parts of the Ukrainian Carpathians.
In the forest zones of the Carpathians, great complex primeval forests have survived to a great extent. They lie in inaccessible places, which the bandit axe of the professional forest destroyer has not yet penetrated. The Carpathian virgin forest is, perhaps, the most beautiful plant formation of the Ukraine. Giant firs, as much as 60 m. in height and six feet thick, raise their dark green slender pyramids above rocky slopes and immense windfallen woods, in which the modern firs lie in piles. Thick shrubbery covers the clearings, while in the eternal semidarkness of the thickets, on rocky ground covered with needles, just an occasional pillow of moss may be found.