Forest meadows of the West Siberian Plain and revision of the order Carici macrourae–Crepidetalia sibiricae

Forest meadows is a characteristic vegetation type of the forest landscapes fr om the Altai-Sayan mountains on the east to the Southern Urals on the west. Communities inhabit open sites that were formed during natural or anthropogenic dynamic of zonal forests. It is the main reason of the floristic origina­lity of the meadows, as reflected by the presence of numerous forest species. Our study is based on the analysis of 573 relevés from 27 associations represented in the previous publications. All forest meadows of the Southern Siberia and Southern Urals are included in the order Carici macrourae–Crepidetalia sibiricae Ermakov et al. 1999 (Ermakov et al., 1999). Among the differential species (d. s.) are common forest herbs: Aegopodium podagraria, Brachypodium pinnatum, Bupleurum aureum, Calamagrostis arundinacea, Crepis sibirica, Dracocephalum ruyschiana, Geranium pseudosibiricum, Hieracium umbellatum, Lilium pilosiusculum, Lupinaster pentaphyllus, Pulmonaria mollis, Rubus saxatilis. CA-ordination shows that the moisture and geographical position are the most important factors influencing the differentiation of forest meadows. Strict dissimilarity in species composition is found between 3 regions — the Altai-Sayan mountains, West Siberian Plain and Southern Urals. The order Carici macrourae–Crepidetalia sibiricae includes three regional alliances. The alliance Crepidion sibiricae Mirkin ex Ermakov, Maltseva et Makunina 1999 (d. s.: Aegopodium podagraria, Brachypodium pinnatum, Bupleurum aureum, Calamagrostis arundinacea, Crepis sibirica, Dracocephalum ruyschiana, Geranium pseudosibiricum, Hieracium umbellatum, Lilium pilosiusculum, Lupinaster pentaphyllus, Pulmonaria mollis, Rubus saxatilis) unites meadows of piedmonts and low mountains of the Altai, Kuznetsk Alatau and Salair. The alliance Heracleo sibirici–Geranion bifolii all. nov. (d.s.: Cirsium setosum, Geranium bifolium, Hera­cleum sibiricum, Poa palustris, Populus tremula, Veronica longifolia, Vicia megalotropis) occurs almost all over the southern part of the West Siberian Plain (Lashchinsky, Tishchenko, 2011; Tishchenko, 2015). The coenoses inhabit the edges of the deciduous ­forests. The alliance Polygonion krascheninnikovii Kashapov 1985 (d. s.: Bistorta major, Geum rivale, Hylotelephium triphyllum, Rumex acetosa, Stachys officinalis, Trifolium medium, Veronica chamaedrys, Viola tricolor) represents communities of the Southern Urals forest belt (Kashapov, 1985; Filinov et al., 2002; Yamalov et al., 2012). Three regional alliances of forest meadows well correspond to the syntaxonomy structure of the class Brachypodio pinnati–Betuletea pendulae Ermakov et al. 1991 with three orders — Carici macrourae–Pinetalia sylvestris Ermakov et al. 1991 (mostly Altai-Sayan mountains), Calamagrostio epigeii–Betuletalia pendulae Korolyuk ex Ermakov et al. 2000 (West Siberian Plain) and Chamaecytiso ruthenici–Pinetalia sylvestris Solomeshch et Ermakov in Ermakov et al. 2000 (Southern Ural). Ranges of this forest orders overlap the areas of corresponding meadow alliances in general. The coniferous and deciduous forests are replaced by grasslands in natural or anthropogenic chronosequences leading to a floristic similarity ­between forest and meadow communities. The moisture gradient is significant for the species composition of meadows. It determines the division of alliances into suballiances of moderately moist and dry forest meadows. Many of xeromesophytes of the class Festuco-Brometea Br.-Bl. et Tx. ex Klika et Hadać 1944 and the order Galietalia veri Mirkin et Naumova 1986 are used as differential species of dry forest meadow suballiances. In diagnosis of moderately moist communities we use forest ­hygromesophytes. The suballiance Crepidenion sibiricae suball. nov. unites moderately moist forest meadows of humid and subhumid regions of the Altai-Sayan mountains. The associations of Aconito barbati–Vicenion unijugae suball. nov. prefer drier habitats. The alliance Anthrisco sylvestris–Aconitenion volubilis suball. nov. is restricted to the Ob-Irtysh watershed (south-eastern regions of the West Siberian Plain). The communities are located at the edges of wet deciduous forests. The west siberian suballiance Heracleo sibirici–Artemisenion macranthae suball. nov. is widespread in southern part of forest zone and northern part of forest-steppe zone. The suballiance Polygonenion krasсheninnikovii Mukhamediarova ex Yamalov et Sultangareeva 2010 represents ­moderately moist meadows of the Southern Ural mountain forest belt. Communities are common both on gentle slopes and in river valleys wh ere they occupy edges and clearings in pine and pine-birch ­forests. Dry variants of forest meadows are included in the suballiance Amoriо montanae–Polygonenion krasсheninnikovii Yamalov suball. nov. These communities are common both on convex slopes and hilltops as well as in dry habitats of river valleys in forest belt along the Southern Urals and forest-steppe belt of the South-Eastern Urals. The analysis of moisture conditions using species indicator values (Korolyuk, 2006) shows similar borderlines between the moderately moist and dry forest meadows: near 61 grade in the Altai-Sajan and Ural mountains, 62 grade — for the West Siberian Plain with wide distribution of the waterlogged landscapes. The analysis of forest meadows demonstrates the necessity in the revision of some associations and subassociations. Formally defined differential species in many cases differ from ones proposed by authors of syntaxa. Some associations are represented by a few relevés and need an additional data. Ecological ranges of some syntaxa along the moisture gradient are overlapped that explains the importance of ecological and geographical analysis of associations and subassociations.