Transformation of soil cyanobacterial-algal cenoses affected by urbanization in the South Ural urban areas

The paper presents the results of long-term studies of soil cyanobacterial-algal cenoses (CAC) in urban areas, including 18 South Ural settlements. The studied soil algae and cyanobacteria species diversity includes 487 species with varieties and forms (Chlorophyta – 231 species, Cyanobacteria – 131 species, Ochrophyta – 58, Bacillariophyta – 52, Streptophyta – 13, Euglenophyta – 2). The edaphophototrophs’ biodiversity is represented by 6 divisions, 12 classes, 32 orders, 89 families, 176 genera. The CAC flora ratio of the South Ural urban areas is 5.4 for species/family, 2.6 for species/genus, and 2.1 for genus/family. Chlamydomonadaceae, Phormidiaceae, Chlorococcaceae, Nostocaceae, and Pseudanabaenaceae are the top five families by the number of species. They account for 33% of the total number of species. We identified groups of frequently occurring algae and cyanobacteria species in the South Ural soil biotopes exposed to recreational or technogenic stress. The CAC taxonomic structure of the settlements in the South Ural forest, forest-steppe, and steppe zones and their mountain counterparts (while maintaining zonal features), has a significant similarity due to the leveling of soil and climatic conditions in cities and synanthropization effect accompanied by introduction of anthropogenically disturbed habitat species into the CAC. We identify the patterns of CAC formation in urban ecosystems, and develop a scheme of CAC transformation in South Ural urban areas. General patterns are associated with changes in the algae and cyanobacteria species diversity and other CAC characteristics with an increase in anthropogenic pressure, as well as with gradual transformation of zonal CAC into azonal ones with subsequent disappearance of autotrophic microbiota. Particular features result from the predominance of one of the leading anthropogenic factor (technogenic pollution or recreational stress). The persistence of Hantzschia amphioxys, Vischeria magna, Botrydiopsis eriensis, etc. decreases with increasing recreational stress, but the persistence of Microcoleus autumnalis, Leptolyngbya foveolarum, Luticola ventricosa, etc. increases. In other words, when the role of some species is weakened, the importance of others increases.