A review of the classification of pine forests (dominated by two-needle pines of the subgenus Diploxylon) of Russia using the Braun-Blanquet approach was carried out. All diversity of pine forests was included in 9 higher units – vegetation classes, of which 3 classes represent typical communities dominated by pine species (Erico–Pinetea Horvat 1959, Koelerio glaucae–Pinetea sylvestris Ermakov class nova hoc loco, Junipero–Pinetea Rivas-Mart. 1965). In the remaining six classes (Vaccinio–Piceetea Br.-Bl. in Br.-Bl.et al. 1939, Carpino–Fagetea Jakucs et Passarge 1968, Quercetea pubescentis Doing-Kraft ex Scamoni et Passarge 1959, Brachypodio–Betuletea Ermakov et al. 1991, Rhytidio–Laricetea Korotkov et Ermakov 1999 and Quercetea mongolicae Song ex Krestov et al. 2006), pine forests are represented as special higher categories (alliances, orders) along with other types of zonal and non-zonal forest vegetation. The characteristics of the main higher units (classes, orders and alliances) are presented, as well as their diagnostic features and problems of classification of some categories are discussed. As a result of the syntaxonomic revision, the name of the class Pyrolo–Pinetea sylvestris Korneck 1974 was rejected, since the alliance Cytiso–Pinion sylvestris Krausch 1962 (the only alliance of order Pulsatillo–Pinetalia Oberd. in Oberd. et al. 1967) was proposed in the original article as provisional (3b). It is proposed to include xerophilous psammophilous pine forests of Europe and Western Siberia into a new class Koelerio glaucae–Pinetea sylvestris class nova hoc loco. The nomenclature type of the class (holotypus) is the order Koelerio glaucae–Pinetalia sylvestris Ermakov 1999. Diagnostic species of the class are Festuca beckeri, Gypsophylla altissima, G. paniculata, Jurinea cyanoides, Koeleria glauca, Oxytropis campanulata, Potentilla humifusa, Veronica spicata, Silene baschkirorum, S. chlorantha, Stipa pennata subsp. sabuletorum, Helichrysum arenarium, Centaurea arenaria, C. marschalliana, Achillea gebleri, Genista tinctoria, Cytisus ruthenica, C. borystenica, Hieracium pilosella, Dianthus arenarius.
Hybrid Types of Waves Propagating in Double Ridged Waveguide with Piecewise-Layer Dielectric Filling
