Dry grasslands on sedimentary outcrops of the Dniester canyon (Ukraine)

Abstract

The main aim of this article is to characterize vegetation data of dry grassland communities on sedimentary outcrops of the Dniester Canyon (Ukraine) ecologically and to provide their syntaxonomy. For this purpose, we collected 155 releves, and included published data from Ukrainian and Moldovian literary sources. We used cluster analysis, including the nomenclatural types of previously described relevant associations from the study area and adjacent territories. As a result, we recognized two associations of the order Alysso-Sedetalia and six of the order Stipo pulcherrimae-Festucetalia pallentis. Two associations of pioneer communities with therophytes and succulents were transferred from the endemic alliance Sempervivo ruthenici-Schivereckion of the class Asplenietea trichomanis to the widely spread alliance Alysso-Sedion of the class Sedo-Scleranthetea. Five associations of petrophytic steppes were transferred from different alliances within the classes Festuco-Brometea (Genisto tetragonae-Seselion peucedanifoliae, Festucion valesiacae) and Sedo-Scleranthetea (Alysso-Sedion) to the alliance Galio campanulati-Poion versicoloris within the class Festuco-Brometea. We also described the new association Cephalario uralensis-Agropyretum cristati. Furthermore, we tested for ecological differences between these associations using ecological scales of the Ukrainian flora and measured soil parameters. We conclude that the relief, geological structure, soils, and climate parameters determine the distribution and diversity of the communities as well as their particular floristic features.