Two new associations of the order Agropyretalia intermedio–repentis in the steppe zone of the Southern Urals, Russia

In 2017–2020, in the territory of the Southern Urals (the Republic of Bashkortostan, Orenburg and Chelyabinsk Regions), we studied the synanthropic communities of transport routes. The syntaxonomic analysis resulted in the description of two associations of the order Agropyretalia intermedio–repentis, the class Artemisietea vulgaris, which are new both for science and the Southern Urals region: Lactucо tataricaе–Psathyrostachyetum junceae ass. nov. and Sisymbrietum volgense ass. nov. They are found in the steppe zone of the Republic of Bashkortostan, Orenburg and Chelyabinsk Regions, along the roadsides of transport routes, less often in wastelands in settlements. Communities dominated by Psathyrostachys juncea are encountered along the roadsides and slopes of highways in the southern part of the Trans–Urals region of the Republic of Bashkortostan. A characteristic feature of the communities of the association Sisymbrietum volgense is the dominance of the invasive Sisymbrium volgense, which settles actively along the transport routes throughout the entire South Urals region. The DCA ordination of the communities of the order Agropyretalia intermedio–repentis confirmed the results of the syntaxonomic analysis and demonstrated significant differences in the ecology of various cenoses by the following ecological factors: moistening, soil texture and structure, soil fertility, and the thermo-climatic factors. The described syntaxa form the most xerophytic branch of the order Agropyretalia intermedio–repentis in the Southern Urals.