Abstract
Aims: To revise the syntaxonomy of the vegetation of steppe depressions (pody), in particular (1) to identify the associations and to reveal their environmental, structural and compositional peculiarities; (2) to assign the associations to higher syntaxa; and (3) to correct nomenclatural aspects according to the ICPN.Study area: Steppe zone of Ukraine, Left-Bank of the Lower Dnieper basin.Methods: 641 relevés were included in the final analysis in the PCOrd program integrated into Juice software. Two expert systems (EVC and EUNIS-ESy) were used to assign relevés to vegetation classes and to EUNIS units.Results: The analysis resulted in nine clusters, which were interpreted asFestuco-Brometea(two units),Molinio-Arrhenatheretea(three units),Isoёto-Nanojuncetea(three units) and one derivate community of theFestuco-Puccinellietea. Detailed characteristics of the species composition, structure, distribution, and environmental conditions are provided for each unit. According to the DCA ordination, the leading factors of the syntaxa differentiation are soil moisture and fluctuating water level.Conclusions: We could clarify the placement of steppe depression vegetation in the system of syntaxonomic units of Europe. The previously described syntaxa of the rank of alliance (Myosuro-Beckmannion eruciformis), suballiance (Galio ruthenici-Caricenion praecocis), and six associations are validated. Two associations and two subassociations are described as a new to science.Taxonomic references: Euro+Med PlantBase (https://www.emplantbase.org), except Mosyakin and Fedoronchuk (1999) forPhlomis scythicaKlokov & Des.-Shost. andTulipa scythicaKlokov & Zoz.Syntaxonomic references: Mucina et al. (2016) for syntaxa from alliance to class level; Dubyna et al. (2019) for associations.Abbreviations: DCA = Detrended Correspondence Analysis; DES = Didukh Ecological Scales; EUNIS = European Nature Information System; EVC = EuroVegChecklist; GIVD = Global Index of Vegetation-Plot Databases; ICPN = International Code of Phytosociological Nomenclature.
Highlights
Steppe depressions are large closed depressions, up to 16,000 ha in area, elliptical or round in shape with gentle slopes and flat bottoms, periodically flooded by meltwater and characterized by Planosol soils and peculiar ephemeral mesic to wet grassland phytocenoses
We could clarify the placement of steppe depression vegetation in the system of syntaxonomic units of Europe
Our aim was to revise the syntaxonomy of the steppe depressions vegetation, in particular (1) to identify the associations and to reveal their environmental, structural and compositional peculiarities; (2) to assign the associations to higher syntaxa; and (3) to correct nomenclatural aspects according to the ICPN
Summary
Steppe depressions (pody in Ukrainian) are large closed depressions, up to 16,000 ha in area, elliptical or round in shape with gentle slopes and flat bottoms, periodically flooded by meltwater and characterized by Planosol soils and peculiar ephemeral mesic to wet grassland phytocenoses. These depressions accumulate natural runoff in poorly drained steppe plains within the periglacial area of the Quaternary glaciation. After the floods of 2003, the average values on the hayfields of the «Black Valley» depression was 12892 ± 518.0 kg/ha in the dry state These values decline rapidly during periods of drought. The dominant species become low, sparse, some hydrophytes disappear from the phytocenosis, enduring a prolonged drought in a latent state (seeds formed under a favorable moisture regime, or underground perennial organs such as caudex, rhizomes, etc.)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
