To the syntaxonomy of the Middle Urals weeding vegetation

The decrease in the crop area and changes in their ratio have led to changes in weed vegetation in the Middle Urals, where its cenoflora was studied relatively well (Tretyakova, 2006; Tretyakova, Kondratkov, 2018; Kondratkov, Tretyakova, 2018; 2019 a, b), while community diversity so far has not yet been assessed. The first results of the ecological and floristic classification of basic crop communities (wheat, barley, oats, corn, potatoes, peas, rapeseed etc.) in six botanical and geographical regions of the taiga and forest-steppe zones (Kulikov et al., 2013) within the Sverdlovsk region, based on the analysis of 160 relevés performed by A. S. Tretyakova, P. V. Kondratkov and N. Yu. Grudanov in 2019, are presented. Communities are classified within the order Aperetalia spicae-venti J. Tx. et Tx. in Malato-Beliz et al. 1960 of the class Papaveretea rhoeadis S. Brullo et al. 2001 nom. conserv. propos. and assigned to the alliance Scleranthion annui (Kruseman et Vlieger 1939 nom. conserv. propos.) Sissingh in Westhoff et al. 1946), which represents the most mesophytic types of weed vegetation in the Urals. Three associations allocated in alliance (two for the first time): Solano nigri–Erodietum cicutarii ass. nov. hoc loco (Table 2, syntaxon 7; Table 4); nomenclature type (holotypus hoc loco) — Table 4, rel. 11 (number in database — 25): Sverdlovsk Region, Sysertskiy district, Kunarskoe village environs, 23.07.2019, authors — A. S. Tretyakova, P. V. Kondratkov);Lamio amplexicaulis–Stellarietum mediae ass. nov. hoc loco (Table 2, syntaxon 8; table 5; nomenclature type (holotypus hoc loco) — Table 5, rel. 10 (number in database — 27): Sverdlovsk Region, Sysertskiy district, Shaidurovo village environs, 22.07.2019, authors — A. S. Tretyakova, P. V. Kondratkov); ass. Euphorbio helioscopiae–Fumarietum officinalis Khasanova et al. 2018. The last one includes two variants. Two unranked communities are also described. Distribution areas of syntaxa cover the southern taiga and pre-forest-steppe pine-birch forests subzones of the taiga zone and the northern forest-steppe subzone of the forest-steppe zone. Habitats are confined mainly to gray forest soils, in rare cases — leached chernozems. The mostly wide distributed is the ass. Euphorbio helioscopiae-Fumarietum officinalis, also common to the south of the study area, in the Republic of Bashkortostan. Аss. Lamio amplexicaulis–Stellarietum mediae is identified in five botanical and geographical districts within the Sverdlovsk region. The confluence with crops and the accompanying system of agriculturе is different. The species composition of the established syntaxa was compared with the associations of the alliance Scleranthion annui described earlier in the Republic of Bashkortostan. The species richness of the latter is generally higher. Differences in species composition of diagnostic groups were revealed. There is decreasing of constancy of Tripleurospermum inodorum, Centaurea cyanus, Polygonum aviculare, Raphanus raphanistrum in the cenoflora of the first one, and both diagnostic species of the more xerophytic alliance Caucalidion lappulae von Rochow 1951 (Galeopsis bifida, Persicaria lapathifolia, Silene noctiflora, Galeopsis ladanum, Melilotus officinalis),apophytes of meadow pasture and forest edges (Medicago lupulina, Trifolium hybridum, Trifolium medium, Achillea millefolium,etc.), xeromesiphytic species (Avena fatua, Amaranthus retroflexus, Setaria viridis, Euphorbia virgata). The latter is probably associated with significant reduction in the field area of some crops (sunflower, flax, etc.). The differences in species composition and ecology of the compared syntaxa are illustrated by the results of ordination analysis. Weed communities of the Southern Urals are localized on the left side of the DCA-ordination diagram, these of the Middle Urals — on the right one. There are changes from the most xerophytic communities of the ass. Linario vulgari-Lactucetum serriolae to the most mesophytic ones of associations Lamio amplexicaulis–Stellarietum mediae and Euphorbio helioscopiae–Fumarietum officialalinae along the first axis. The second axis reveals the change in species composition under the influence of the agronomic factor — culture and the corresponding agricultural system and communities of winter cereals (associations Consolido regali–Centaureetum cyanae and Galeopsetum bifidae) are replaced by communities of spring cereals and row crops (corn, potatoes, peas, rapeseed), which are assigned to the associations Linario vulgari–Lactucetum serriolae and Solanо nigri–Erodietum cicutarii.