Steppe vegetation of the hilly area along the Ural River (the steppe zone of Chelyabinsk Region)
Authors: Zolotareva N. V. , Korolyuk A. Yu. , Makunina N. I. , Podgaevskaya E. N. 
Published: December 2024

The major part of the steppe zone territory within Chelyabinsk Region is plowed now: farmlands occupy from 62 % up to 70 % of its territory. Natural steppe vegetation has remained only on a rugged terrain such as the hilly area along the Ural River («Ural Hills»). It is a hilly stripe 160 km long and 15 km wide along the banks of the Ural River which spreads in a meridional direction from the northern limit of the steppe zone to the south. Their relief, the complexity of the soil and vegetation cover differ noticeably from those of the Southern Trans-Urals, the steppe vegetation of which was characterized earlier (Zolotareva et al., 2023). The aim of our work is to reveal the diversity of the steppes of hilly area along the Ural Riverand to integrate them in the current system of floristic classification. This will precise the list of the syntaxa of Festuco-Brometea class within the steppe zone of the Chelyabinsk region.

The «Ural Hills» are extended along the western border of the Trans-Ural peneplain – a foothill plain at the foot of the eastern ridges of the Urals. Average altitudes are 300–400 m above sea level, relative elevations above the surrounding terrain vary from 20 to 100 m. Igneous, sedimentary and metamorphic rocks of the Devonian and Carboniferous origin dominate. Ordinary and southern chernozems occupy flat area, underdeveloped gravelly chernozems are common along the slopes of the hills, solonetz soils are rare. Steppes prevail in vegetation cover, small birch and aspen-birch forests are found on the northern hill slopes.

The article is based on the analysis of 334 geobotanical releves made by the authors in 2012–2021 in the south-western regions of the Chelyabinsk Region. The classification was carried out using a modified TWINSPAN algorithm (Roleček et al., 2009) in the JUICE 7.0 package (Tichý, 2002). The vegetation of the Festuco-Brometea class on the «Ural Hills» is represented by 10 associations, 3 subassociations and 8 variants from 2 orders: Brachypodietalia pinnati (meadow steppes) and Helictotricho-Stipetalia (herb-bunchgrass steppes). 3 associations (Tanaceto kittaryani–Ephedretum distachyae ass. nov., Nepeto ucranicae–Stipetum lessingianae ass. nov., Galio tinctorii–Helictotrichetum desertorum ass. nov.) and 7 variants have been described for the first time, 1 association (Scorzonero austriacae–Stipetum lessingianae Yamalov, Bayanov et Mirkin ex Yamalov, Zolotareva, Korolyuk ass. nov.) has been validated.

«Ural Hills» as a part of the Trans-Ural peneplain has the basic patterns of vegetation cover as in the South Trans-Urals, (Zolotareva et al., 2023): 1) propersteppe vegetation belongs to order Helictotricho-Stipetalia, 2) steppes of ass. Helictotricho desertorum–Stipetum rubentis are zonal, 3) however, zonal steppes occupied flat area and gentle hill slopes previously, now most of them are plowed, 4) remaining straps of background steppe association have been transformed into impoverished communities of ass. Artemisio austriacae–Stipetum capillatae under overgraizing.

Meadow steppes of order Brachypodietalia pinnati have limited distribution in «Ural Hills»; they occupy only the most humid habitats of slope lower parts, hollows between the hills, the edges of small-leaved forests. Meadow steppes of «Ural Hills» are found to refer to 3 associations. Two of them are common to the entire territory of the Southern Trans-Urals; these are ass. Poo angustifoliae–Stipetum pennatae and ass. Galio veri–Stipetum tirsae. Area of the third association, ass. Galio tinctorii–Helictotrichetum desertorum, is limited by rough relief of «Ural Hills». Mesophytic conditions of northern hill slopes allow the growth of the dominants of zonal steppes of the order Helictotricho-Stipetalia and meadow-steppe species of the order Brachypodietalia pinnati.

Association Galio tinctorii–Helictotrichetum desertorum ass. nov. (Table 5, relevés 1–18). Nomenclature type (holotypus): Table 5, relevé 9 (field number nz18–010), Russian Federation, Agapovsky district, environs of vil. Svetlogorsk, 53.12724° N., 59.057° E., 09.06.2018, author — N. V. Zolotareva.

The large meridional extent of «Ural Hills» from south to north causes changes in its vegetation. In the southern part of these area,patches of dry steppes of alliance Stipion korshinskyi are present among zonal rich bunchgrass steppes of alliance Helictotricho desertorum–Stipion rubentis: these are steppes of ass. Nepeto ucranicae–Stipetum lessingianae and of ass. Scorzonero austriacae–Stipetum lessingianae. They sometimes occur in the northern part of the hilly area along the Ural River, where they are extrazonal.

Association Nepeto ucranicae–Stipetum lessingianae ass. nov. (Table 13, relevés 1–15). Nomenclature type (holotypus): Table 13, relevé 11 (field number 21–187), Russian Federation, Chelyabinsk region, Kizilsky district, environs of vil. Ershovsky, 52.51098° N., 59.21168° E., 30.05.2021, author — A. Yu. Korolyuk.

AssociationScorzonero austriacae–Stipetum lessingianae Yamalov, Bayanov et Mirkin ex Yamalov, Zolotareva, Korolyuk ass. nov. (Table 12, relevés 1–18). Nomenclature type (holotypus): Table 12, relevé 4 (field number MA96–005), Russian Federation, Republic of Bashkortostan, Khaibullinskii district, 8.5 km SE vil. Gadileva, 51.867° N., 58.583° E., 22.07.1996, author — A. A. Muldashev.

According to different moisture supply, soil salinity and rocks increase the number of Festuco-Brometea syntaxa; there are 2 edaphic variants of zonal steppes: petrophytic and saline ones. Gravelly soils and rock outcrops are widespread on the slopes and tops of «Ural Hills», so petrophytic steppes are common and widespread here. They were ascribed to 2 associations. Petrophytic steppes of subass. Diantho acicularis–Orostachyetum spinosae inops are widespread in the Southern Trans-Urals and in the northern part of hilly area along the Ural River; they belong to alliance Helictotricho desertorum–Orostachyion spinosae. Petrophytic steppes of more xerophytic ass. Tanaceto kittaryani–Ephedretum distachyae occur in the southern part of the hilly area, they were included in alliance Elytrigion pruiniferae, uniting the most xerophytic petrophytic steppes of order Helictotricho-Stipetalia.

Association Tanaceto kittaryani–Ephedretum distachyae ass. nov. (Table 15, relevés 1–34). Nomenclature type (holotypus): Table 15, relevé 6 (field number nz21–30), Russian Federation, Chelyabinsk Region, Kizilsky district, environs of the vil. Ershovsky, 52.49176° N, 59.16082° E, 29.05.2021, author — N. V. Zolotareva.

The saline steppes of ass. Artemisio nitrosae–Festucetum valesiacae often occur in the east of the Chelyabinsk Region in places where salt-bearing tertiary clays are wedged out; in «Ural Hills» they take the same places: rare tertiary salt-bearing rocks in northern part of this hilly area.

Thus, previously found on the territory of the Trans-Urals peneplain steppe syntaxa of Festuco-Brometea class form the basis of the steppe vegetation of the hilly area along the Ural River too. But hilly relief and large latitudinal range of hilly area along Ural River cause the emergence of the new types of steppes. The new steppe syntaxa described in the article complement the information about the diversity of steppe vegetation of the Southern Trans-Urals.