Syntaxonomy and ecological differentiation of vegetation of the class Festuco-Brometea in Mykhailivska Tsilyna Nature Reserve

The article is devoted to syntaxonomy and synphytoindication of steppe vegetation in Mykhailivska Tsilyna Nature Reserve (Sumy Region). Based on phytosociological materials collected in 2021–2022 and literature data, changes of steppe vegetation in the reserve over the past ten years have been analyzed. The plant communities of the class Festuco-Brometea were identified as two subassociations and two variants in three associations, belonging to one alliance and one order. The article provides characteristics of the syntaxa, their ecological requirements, synphytoindication indexes, and results of DCA-ordination of the obtained indexes of ecological factors. It has been found that the main ecological gradients affecting ecological and territorial differentiation of the syntaxa are the soil humidity, nitrogen content in soil, soil aeration, and total salt regime. During the study, an increasing mesophytization of the steppe vegetation was observed, caused by the absence of mowing on the territories that formerly were under the constant mowing regime.