REGULARITIES OF GEOGRAPHICAL DISTRIBUTION OF DOWNY OAK FORESTS IN LOWLANDS OF UKRAINE

Abstract

Investigating the regularities of geographical distribution and the current state of rare phytocoenosis is an essential task in ecological research. Downy oak (Quercus pubescens Willd.) forests represent the most uncommon plant community in the lowlands of Ukraine. Unlike widespread mountainous downy oak forests that form high-altitude vegetation belts in the Crimean Mountains, isolated lowland downy oak woods are extremely rare and are documented only in the Odeska and Vinnytska regions, situated at the eastern limit of the European range. These woods are found along the channels of the Dnister River and its tributaries, Kuchurgan and Velykij Kujalnyk. Overall, insular lowland downy oak woods in Eastern Europe are extrazonal relic plant communities that had a much more extensive range in the past, reaching the Wolhynian Upland during the Riss-Würm interglacial period. Deforestation on slopes, replacement of natural forests with Robinia pseudoacacia and Gleditsia triacanthos plantations, and cattle grazing have led to the isolation of Quercus pubescens range near the eastern limit. This has transformed its primary linear populations into local insular populations and resulted in the degradation of lowland downy woods in Ukraine. However, the conclusion that lowland downy oak woods have been completely eliminated in Ukraine and should be removed from the Green Book of Ukraine is mistaken. The core populations of Quercus pubescens are preserved in reserve Dibrowa Manzyrska in Odeska region and in downe oak wood on the valley of Dnister river. Given high phytososological value of transnistrian downe oak in Vinnicka region, it must be preserved as botanical reserve.