Weed communities with alien plant species on the south-east area of the Orenburg Region

The presence of agrocoenotic factors constantly acting on segmental (weed-field) communities leads to a high level of community invasion – a potential opportunity to accept new species. In many cases, it is through synanthropic communities that invasions of alien species occur in the Urals, which cause significant damage to both agriculture and the entire economy of the region as a whole. The aim of investigation is to survey and identify the coenotic diversity of communities involving alien species in the steppe zone of the southeastern part of the Orenburg Region. The paper provides data on weed communities with the participation of Acroptilon repens, the Sisymbrium volgense and Artemisia sieversiana. Communities were identified in spring wheat crops in the southeast of the Orenburg Region (Dombarovsky and Svetlinsky administrative districts). Communities develop on dark chestnut soils in arid conditions of the steppe zone. As a result of a synaxonomic analysis, communities were classified into three new variants of the association Lactucetum tataricae Rudakov in Mirkin et al. 1985 previously described in the Republic of Bashkortostan. Perennial weed species prevail in the agrobiological spectrum of the coenoflora nucleus of the studied segetal communities, the share of which is 70%. The most active of them are root-sprung perennials, which are found with high constancy and often dominate: Acroptilon repens, Fallopia convolvulus, Cirsium arvense, Convolvulus arvensis, Lactuca tatarica, Euphorbia virgata. Using the indirect ordination method (DCA), the features of ecological differentiation of communities are demonstrated. The studied phytocoenoses are associated with the driest habitats with poor soils.