Participation of Ceratocarpus arenarius (Chenopodiaceae) in the Late Glacial and Holocene palynofloras of the plain part of Ukraine

Results of our analysis and generalization of paleofloristic (paleopalynological) data on the participation of pollen grains of Ceratocarpus arenarius (Chenopodiaceae) in 18 palynofloras of deposits of the last climatic phases of the Late Glacial (Allerød, Late/Younger Dryas) and the Holocene of the Forest, Forest-Steppe, and Steppe zones of Ukraine are presented. For the first time the spatiotemporal patterns of occurrence of C. arenarius in the plain part of Ukraine are reconstructed. It has been established that in the Allerød and the Younger Dryas, participation of this species in the plant cover was determined mainly by various natural factors. In the Holocene, changes in the distribution patterns of C. arenarius occurred under the influence of both natural and anthropogenic factors. The obtained paleofloristic material shows that the influence of the latter factors on the changes in the composition of the vegetation is registered starting with the Middle Holocene, and it significantly increases during the Late Holocene. At this time, the boundaries of the natural (native, not influenced by human activities) range of C. arenarius in the plain part of Ukraine are difficult to outline. In most cases the species participates in the formation of plant communities of synanthropic vegetation, mainly in the southern part of Ukraine. Diagnostic characters of pollen grains of C. arenarius are discussed and specified. The following characters are recommended for using in practical paleopalynology: dimensions of pollen grains and pores, number of pores, distance between pore margins, exine texture and thickness, and distinctness of columella. The characters that distinguish pollen grains of C. arenarius from pollen of Krascheninnikovia ceratoides (belonging to the same tribe) are reported, as well as their shared characters.