Segetal vegetation of the Southern Urals: alliance Scleranthion annui (Kruseman et Vlieger 1939) Sissingh in Westhoff et al. 1946

Segetal communities are the sets the weed plant species which are formed under the influence of edafo-climatic conditions and the mode of disturbance — the systems of processing of the soil in a crop rotation (so-called agrotechnical factor) (Mirkin, Naumova, 2012). The history of their study in the Southern Urals is more than 80 years old (Dmitriyev, 1935; Gaysin, 1950; Minibaev, 1961; Bakhtizin, Rakhimov, 1968; Denisova et al., 1970). Development of classification according to floristic approach has been begun in the 1980th by Ufa geobotanists. Results have been generalized in the collective monography (Mirkin et al., 1985). A repeated syntaxonomical analysis was carried out a long time later only for the Trans-Ural region of the Republic of Bashkortostan (Yamalov et al., 2007). The purpose of the present research is to reveal a phytodiversity of weed vegetation of the Southern Urals, using all available geobotanical data, and to develop its syntaxonomy. This paper presents the results of the classification of one of the three allocated alliances. The dataset contains 1171 relevés: 891 were performed by authors in the course of the 2002–2016 field seasons, while 280 are taken from the mentioned monography (Mirkin et al., 1985). All plots belong to class Papaveretea rhoeadis which combines annual weed vegetation of winter, summer and the row-crop cultures, gardens and initial stages of succession (Mucina et al., 2016). Within the class these are distributed between orders Aperetalia spicae-venti J. Tx. et Tx. in Malato-Beliz et al. 1960 and Papaveretalia rhoeadis Hüppe et Hofmeister ex Theurillat et al. 1995. Alliance Scleranthion annui (Kruseman et Vlieger 1939) Sissingh in Westhoff et al. 1946 goes to the first one, while Caucalidion Tx. ex von Rochow 1951 and Lactucion tataricae Rudakov in Mirkin et al. 1985 — to the second. The alliances are well differentiated floristically (Table 2) and according to zonal affinity. Alliance Scleranthion annui (Fig. 2) combines the most mesophyte communities distributed mainly on gray forest and soddy podzolic soils, rarer on other types of soils in the southern part of the forest zone and northern part of the forest-steppe one. Diagnostic group includes terophytes: Centaurea cyanus, Tripleurospermum perforatum, Euphorbia helioscopia, Capsella bursa-pastoris, Polygonum aviculare, Viola arvensis, Raphanus raphanistrum. Alliance Caucalidion (Fig. 3) combines communities on rich carbonate chernozem soils of the forest-steppe zone. It is intermediate between Scleranthion annui and Lactucion tataricae in zonal gradient. Diagnostic species are Galeopsis ladanum, Sonchus arvensis, Persicaria lapathifolia, Galeopsis bifida, Silene noctiflora, Erodium cicutarium, Thlaspi arvense, Galium aparine. They are also highly constant in communities of alliance Scleranthion annui in the forest zone, but are absent or low constant in these of alliance Lactucion tataricae in the steppe zone. Alliance Lactucion tataricae (Fig. 4) combines floristically impoverished communities in the steppe zone on south chernozem soils. Two species are diagnostic: hemicryptophyte Lactuca tatarica and terophyte Panicum miliaceum. There are 4 associations, 3 subassociations and 5 variants within the alliance Scleranthion annui. The ass. Linario vulgaris–Lactucetum serriolae ass. nov. hoc loco (Table 4, 5; holotypus — Table5, N 8) combines communities of winter and row-crop cultures, widely spread in the forest zone and northern part of the forest-steppe one on gray forest and soddy podzolic soils, which are common in the northernmost regions of the Cis-Urals within the territory of the Republic of Bashkortostan. Some of them occur in northern flat forest areas as well as in the northern forest-steppe, while few of these are located in the foothill forest regions. Besides the species of alliance Scleranthion annui and class Papaveretea rhoeadis there are ruderal perennials of classes Artemisietea vulgaris Lohmeyer et al. in Tx. ex von Rochow 1951 and Polygono arenastri–Poëtea annuae Rivas-Martínez 1975 corr. Rivas-Martínez et al. 1991, such as Artemisia absinthium, A. vulgaris, Plantago major, Elytrigia repens etc. which are character for disturbed habitats. Also important is the presence of apophytes of classes Molinio-Arrhenatheretea R. Tx. 1937 and Trifolio-Geranietea sanguinei Th. Müller 1962 (Poa pratensis, Trifolium pratense, Knautia arvensis, Pimpinella saxifraga etc.) common in meadows and forest edges. The ass. Consolido regalis–Centaureetum cyani ass. nov. hoc loco (Table 6; holotypus — N 26) combines communities of winter and summer crops (wheat, rye, rarer barley), widely spread in forest zone and northern part of forest-steppe one. They are located on gray forest and soddy podzolic soils. Three subassociations are discribed within association according the agrotechnology of the prevailing culture. The ass. Galeopsietum bifidae combines communities of winter crops which were widely spread in a forest-steppe zone on the podzolic chernozem in the 1980th (Mirkin, et al., 1985). The association is intermediate between the alliance Scleranthion annui and Caucalidion. The ass. Euphorbio helioscopiae–Fumarietum officinalis ass. nov. hoc loco (Table 7, 8; holotypus — Table 8, N 9) combines communities mainly of the row-crop and the summer cultures in the forest zone in flat and mountain regions and also in northern part of the forest-steppe zone. They are located on gray forest soils and rarer on the podzolic chernozem. Differentiation of associations is illustrated by the DCA-ordination data (Fig. 6). The first axis is interpreted as a complex gradient of moistening and an agrocoenotic factor. Along the second axis of soil richness-salinity the communities on soddy podzolic soils are replaced by those on mountain variants of gray forest soils and the podzolic chernozem.