Floristic Differentiation of Meadow Vegetation Plant Species in the Forest-Steppe Zone of the Priobskoye Plateau

Meadows form the zonal vegetation of the forest-steppe zone and are characterized by high heterogeneity. Currently, the meadows are used as hayfields and pastures, and, in most cases, are under a heavy anthropogenic pressure. Low-disturbed communities occupy only small areas in glades and on the edges of the birch forests, along the outskirts of fields, and on the slopes of gullies. The species composition of the meadows is formed by various ecological groups that indicate the conditions of habitats. These groups can also be used as a basis for vegetation classification. The purpose of the study is to identify the phytocoenotic diversity of the meadows and define species of indication value in the forest-steppe zone of the Priobskoye plateau. The research was carried out on the left bank of the Ob River in the forest-steppe zone (Novosibirsk oblast and Altai krai) (See Fig. 1). The study is based on 531 releves of meadow communities. The cluster analysis was used to identify the phytocoenotic diversity of the meadows. A general table was built in the IBIS 7.2 program and was processed in the JUICE 7.0 by the Modified TWINSPAN Classification and TWINSPAN algorithms. The resulting clusters were compared and differential species were identified (See Table). Position of the meadow communities on main ecological gradients were assessed using the plant indicator values (See Fig. 2). The cluster analysis divided the dataset into 6 clusters. The first cluster comprises steppe alkaline meadows. Such meadows are characterized by sparse herbaceous cover and a small number of species. Salt-tolerant mesoxerophytes Seseli strictum, Galatella biflora, Artemisia pontica, etc. dominate. These meadows are the driest among the others (See Fig. 2). The second cluster comprises steppe meadows. At present, most of these meadows are tilled. They are dominated by mesoxerophytes such as Cala-magrostis epigeios, Poa angustifolia, Peucedanum morisonii, etc. Such meadows develop on dry soils (grades 54-55; See Fig. 2). The third cluster features typical dry meadows. They develop on the forest clearings and on idle lands. In the Priobskoye plateau, these meadows are the most common type among the other meadows. Dominants are eumesophytes and mesoxerophytes: Bromopsis inermis, Poa angustifolia, Calamagrostis epigeios, Dactylis glomerata, Pimpinella saxifraga, etc. Their position is at grade 56 on the moisture gradient (See Fig. 2). Dry forest meadows of the fourth cluster are found in small areas on the edges and in the glades of birch forests (grade 59; See Fig. 2). In these meadows, the dominants are Brachypodium pinnatum, Bromopsis inermis, Rubus saxatilis, and others. The fifth cluster includes salinized forbgrass meadows. They feature salt-resistant mesophytes such as Jacobaea erucifolia, Glaux maritima, Parnassia palustris, etc. These meadows are widespread in lowlands, in the valleys of small rivers, and in the outskirts of damp birch forests. On the moisture gradient (See Fig. 2), they are located at grades 61-62 that corresponds to the dry and fresh meadows. The sixth cluster incorporates wet forest meadows that are developed in the conditions of high soil moisture (grades 63-65; See Fig. 2). Among the main dominant species are Filipendula ulmaria, Dactylis glomerata, Anthriscus sylvestris, Angelica sylvestris, etc. The numerical analysis of releves showed a high diversity of meadows in both dominant and floristic classifications. More than half of the diagnostically significant species (65 out of 95) have differential value for one of the six community types. These species have a high indication value as they are stenotopic. Steppe alkaline meadows (type 1) are diagnosed by mesoxerophytic hemihalophytes Limonium gmelinii, Seseli strictum, etc. Perennial meadow-steppe mesoxerophytes Stipa pennata, Veronica spuria, etc. are characteristic for steppe meadows (type 2) and meadow steppes. Typical dry meadows (type 3) differ by the presence of bi- and perennial eumesophytes Convolvulus arvensis, Berteroa incana, etc., which diagnose disturbed habitats and anthropogenic pressure. Perennial mesoxerophytes and eumesophytes (Pulmonaria mollis, Brachypodium pin-natum, etc.) indicate dry forest meadows (type 4). Salinized forb-grass meadows (type 5) are diagnosed by salt-tolerant mesoxerophytes, eumesophytes and mesohygrophytes (Sonchus arvensis, Jacobaea erucifolia, etc.) whose habitats are slightly salinized. In wet forest meadows (type 6) between dominant species are perennial eumesophytes and mesohygrophytes: Filipendula ulmaria, Heracleum sibiricum, etc. Another 16 species have a high indicator value, being determinant for two types of communities. They are confined to relatively narrow segments on the moisture or salinity gradient. Thus, the species Artemisia rupestris, Plantago salsa, and others characterize saline habitats, developing in different moisture conditions. The most numerous group with Phleum phleoides, Artemisia glauca, and others is characteristic of dry habitats. The meadow vegetation of the forest-steppe zone of the Priobskoye plateau is characterized by high floristic and phytocenotic diversity. Many plant species have an indicator value and can serve as a basis for determining the diagnostic species of syntaxa of various ranks. The article contains 2 figures, 1 table, 30 references. The Authors declare no conflict of interest.

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