New segetal communities of sunflower crops in the Orenburg Region

The diversity of weed-field communities of sunflower crops within the forest-steppe zone of the Orenburg Region (Abdulinskiy, Matveevskiy, Oktyabrskiy, Aleksandrovskiy, Sharlykskiy districts) was studied. The communities in the system of ecological-floristic classification units are assigned to the new variant Orobanche cumana of the Amarantho blitoides – Lactucetum tataricae Khasanova et al. 2019. In the core of the cenoflora of communities juvenile weed species prevail. The most active of them are late spring annuals (Amaranthus blitoides, Panicum miliaceum, Amaranthus retroflexus, Setaria viridis) and early spring annuals (Chenopodium album, Fallopia convolvulus, Camelina microcarpa). Root perennials such as Lactuca tatarica, Convolvulus arvensis, Euphorbia virgata, Cirsium arvense have also a high proportion. A distinctive feature of the communities is the participation in their floristic composition of a dangerous quarantine species – Sunflower broomrape (Orobanche cumana). Modeling the area of the association under a moderate scenario of climate change shows that the distribution of communities by 2050 can cover almost the entire territory of the Cis-Urals (within the Republic of Bashkortostan). It is necessary to organize a monitoring system for the range of these communities in the Southern Urals.