Communities of the class Festuco-Brometea Br.-Bl. et Tx. ex Soó 1947 in Mesyagutovskaya and Krasnoufimskaya forest-steppes (the Middle Cis-Ural region)

Abstract

There is a series of forest-steppe islands in the forest zone of the Middle Cis-Ural region. Two of these (Krasnoufimskaya and Mesyagutovskaya forest-steppes) of the considerable size and are of great interest for the study of steppe and meadow-steppe vegetation diversity in the northern locations of the Cis-Urals region. In the recent decades the studies of Mesyagutovskaya forest-steppe herbaceous vegetation with their syntaxonomy were done (Yamalov, Kucherova, 2009; Yamalov et al., 2013). For Krasno­ufimskaya forest-steppe such research was not carried out. Our aim was to make the revision of previously described syntaxa on this territory using the new data and to determine their position within the class Festuco-Brometea according to modern views. Existence of the forest-steppe landscape in the forest zone of Middle Cis-Urals region is due tothebarrier effect of the Ufa Plateau, intercepting part of the rainfall coming from the Atlantic transport. The climate of the study area is continental with moderately cold winter and moderately warm summer. Bedrocks here are limestones, sandstones and slates. The extrazonal northern forest-steppe extends for two degrees in the latitudinal direction. Mountainousness increases from the north to the south, while the climate becomes drier and warmer (Table 1). The central part of Krasnoufimskaya forest-steppe is flat; its agricultural development began in 17th century, so therefore the steppe areas were preserved only on the slopes of river valleys and hills. The territory of Mesyagutovskaya forest-steppe is more mountainous, therefore, the number of preserved steppe plots here is greater than in the Krasnoufimsk area (Fig. 2, 8). The initial dataset includes 295 relevés collected in the course of the field study in 2007–2014 in some locations of the Sverdlovsk Region and the Bashkor­tostan Republic. After the revision according to EuroVegChecklist Expert System (Mucina et al., 2016) the relevés previously assigned to the class Moli­nio-Arrhenatheretea were excluded, thus the data of this paper are based on the analysis of 260 relevés. All relevés were classified using the modified TWINSPAN algorithm (Roleček et al., 2009) in JUICE 7.0 (Tichý, 2002). According to TWINSPAN results the dataset was divided into 9 groups which formed two clusters (Fig. 1). Each of them is differentiated by group of species: cluster A — by the meso-xerophyte species of meadow steppes and xeric meadows, including 18 diagnostic species of the order Brachypodietalia pinnati (syn. Brometalia erecti) (Willner et al., 2017, 2019): Amoria montana, Brachypodium pinnatum, Carex caryophyllea, Dactylis glomerata, Festuca pratensis, Lathyrus pratensis, Leucanthemum vulgare, Ranunculus polyanthemos, Trifolium pratense, Vicia cracca, etc.; cluster B — by the widespread steppe species, including diagnostic ones of the class Festuco-Brometea (Anemone sylvestris, Artemisia latifolia, Campanula sibirica, Koeleria cristata, Scabiosa ochroleuca, Stipa capillata) and the order Helictotricho-Stipetalia (Helictotrichon desertorum, Onosma simplicissima, Oxy­tropis pilosa, Pilosella echioides, Potentilla humifusa, Salvia stepposa) (Korolyuk, 2017). Thus, cluster A combines meadow steppes and xeric meadows on rich soil habitats, and these communities correspond to the order Brachypodietalia pinnati. Cluster B combines petrophytic steppes on dry rocky habitats of insolated slopes, and these communities correspond to the order Helictotricho-Stipetalia. Ordination showed that such ecological factors as habitat moisture, soil fertility and rockiness are important in differentiation of syntaxa of the class Festuco-Brometea (Fig. 13). The vegetation of the class Festuco-Brometea in the northern forest-steppe of the Cis-Urals region belongs to 2 orders, 6 associations, 9 subassociations, 2 variants and 3 communities. Among them 1 association (Centaureo sibiricae–Stipetum pulcherrimae Yamalov ass. nov. hoc loco), 9 subassociations (Leucanthemo vulgaris–Stipetum pennatae typicum subass. nov. hoc loco, L. v.–S. p. festucetosum pratensis subass. nov. hoc loco, L. v.–S. p. vicietosum tenuifoliae subass. nov. hoc loco, Drabo sibiricae–Primu­letum macrocalycis typicum subass. nov. hoc loco, D. s.–P. m. potentilletosum humifusae subass. nov. hoc loco, Fragario viridis–Caraganetum fruticis poetosum angustifoliae Yamalov subass. nov. hoc loco, Stipo pennatae–Centauretum sibiricae typicum subass. nov. hoc loco, S. p.–C. s. polygonatetosum odorati subass. nov. hoc loco, S. p.–C. s. polygaletosum sibiricae subass. nov. hoc loco) and 3 communities (Spiraea crenata, Festuca valesiaca–Alyssum tortuosum, Anthemis subtinctoria–Aster alpinus) are new. One association (Stipo pennatae–Centauretum sibiricae Yamalov et al. ex Zolotareva, Korolyuk, Yamalov ass. nov. hoc loco) has been validated. Syntaxa of the order Brachypodietalia pinnati represent the base of the class Festuco-Brometea in the study area. Currently, only meadow steppes of the ass. Leucanthemo vulgaris–Stipetum pennatae are widespread throughout the extrazonal forest-steppe. Steppe-meadows of the ass. Drabo sibiricae–Primuletum macrocalycis) are found in the Mesyagutovskaya area; in the northern part the same landscape positions are occupied by communities of the class Molinio-Arrhenatheretea. The steppe shrubs in the northern and the southern parts of the forest-steppe area are also different: in the south these are dominated by Caragana frutex and corresponds to the ass. Fragario viridis–Caraganetum fruticis, in the north (Krasnoufimskaya area) Caragana frutex is not found and shrub communitiesaredominated by Spiraea crenata (Fig. 2). Syntaxa of the order Helictotricho-Stipetalia occur on limestones exposures. Currently, the petrophytic steppes of the ass. Stipo pennatae–Centauretum sibiri­cae are known overall in the extrazonal forest-steppe, while the communities of the ass. Centaureo sibiricae–Stipetum pulcherrimae are registered only in the southern part of Mesyagutovskaya forest-steppe; northwards locations of this association diagnostic species are rare, some of these are absent in the Krasnoufimskaya forest-steppe area. The other syntaxa of petrophytic steppes with many relict and endemic species occur locally on the slopes of ancient reeves due to the unique combination of factors (Fig. 8).