Ruderal vegetation of Kyiv City. I. Class Stellarietea mediae Tx. et al. in Tx. 1950

This article, which is the first contribution in a series on the ruderal vegetation of the city of Kyiv, presents results of our studies of Stellarietea mediae plant communities occurring in the city. Their current state and phytocoenotic diversity has been determined. Based on modern methods of statistical data analyses, a classification scheme of Stellarietea mediae vegetation in the study area was developed and the leading factors of territorial and ecological differentiation of phytocoenoses were identified. It has been established that within Kyiv City, this class is represented by 24 associations and 3 basal communities belonging to 8 alliances and 4 orders. Their territorial distribution determines the types and intensity of anthropogenic disturbances, as well as the types of soil and its mechanical structure. Selected syntaxa are characterized and compared with their equivalents from other areas of Ukraine. It has been found that the main differences are at the level of co-occurring species, the composition of which mostly correlates with the types of anthropogenic disturbances and availability of water and mineral nutrients. According to the results of the ordination, it has been found that the distribution patterns of plant communities of Stellarietea mediae occur along the salt regime gradient of the edaphotope, as well as of ombro-, cryo-, and thermal regimes of the climate. Based on the phytoindication analysis, the ecological optimums of the plant communities in relation to the leading ecological factors were determined. The performed research supplements the available information about the presence and distribution of such associations as: Digitarietum ischaemii, Setario viridis-Erigeronetum canadensis, and Ambrosietum artemisiifoliae, in the territory of Ukraine. The proposed syntaxonomic scheme should become a basis of typological developments for strategic planning and practical implementation of activities for optimizing the urban environment and for sustainable development of the Kyiv urban agglomeration.