Since those primeval days, only a very few natural changes have occurred in the vegetation of the Ukraine. However, man, thru his cultural activity, has wrought many changes in the plant-world of the country. The forest region occupies barely one-fifth of the Ukrainian territory, only the northwestern and northern borderlands. The southeastern border of the forest region [100]extends from the Prut and Dniester on the western boundary of Pokutye and Podolia in a curve to the source of the Buh, then near the northern boundary of the Dnieper Plateau east as far as Kiev, and thence toward the northeast as far as the source of the Aka. This boundary, however, is not sharp. In numerous peninsulas the compact forest penetrates the adjacent transition region toward the southeast. On the other hand, this forest boundary coincides almost exactly with the northern boundary of the black soil. The soil of the forest region is in general poor. Only in higher places we find fertile turf; beyond that sandy soil and the podsol, rich in quartz, predominate. The prevailing plant formation in this region is the forest. It once covered the entire region and was thinned to any great extent only within the last two centuries. What these primeval forests were like we can now tell in only a few districts of the Polissye and in the famous virgin forest of Biloveza, which lies in the extreme northwest corner of the Ukrainian territory. Here we see the primeval forest in its mighty size and beauty. In wind-fallen woods, several meters high, rotten, decaying stumps cover the ground. Their roots stand up high into the air above swampy holes and vast masses of rotting remains of plants. Above this swampy fen rise, like a vast mass of pillars, the knotty trunks of century-old oaks and lindens, ash and aspen, and the slender pine and fir. High above the ground their branches intertwine. All strive up toward the sun, for a continuous semi-darkness reigns below. Shrub and herb vegetation thrives only in clearings; beyond that only last year’s leaves, needles, and a mysteriously glowing decay cover the ground. Dead silence, only occasionally broken by the hammering of a woodpecker or by the timid voice of a bird, reigns everywhere, making all the more impressive the mighty roaring of the lofty crowns in the storm. [101] As to their composition, the woods of the Ukrainian forest region are mixed, altho local conditions cause one or the other species of tree to predominate. The Ukrainian forest region may be divided into two regions by a line running thru Lublin southeast toward Lutzk. Southwest of this line extends the Central European forest zone, northeast of it the Northern European forest zone.