Abstract
The nature reserve Mykhailivska Tsilyna is located in Sumy region, in the northern part of Forest-Steppe zone of Ukraine. The area of virgin northern meadow-steppe is protected there. A new, large-scale vegetation map (scale 1:10000) of the reserve (the first one in its new borders) had been created. The main units of mapping are complexes of plant communities in ranks of associations, subassociations and variants. In total, 27 such complexes and 10 units of another rank have been identified. The map shows vegetation cover changes over a period of strict protection (2011–2023). The most common classes of vegetation in the reserve are: Molinio-Arrhenatheretea, Artemisietea vulgaris and Festuco-Brometea. Main changes in the vegetation cover of the reserve's old territory are manifested in the form of steppe transformation: from meadow-steppe areas to more mesic shrub-steppe with dominating Cytisus ruthenicus and forb communities with dominating Euphorbia semivillosa. In these communities can be seen a decrease in the share of tussock grasses and an increase in the share of rhizomatous grasses. The same process is occurring in the reserve's new territory, but phytocenoses are different there.