The Norsky State Nature Reserve is located in Selemdzhinsky district of the Amurskaya oblast. Its area is 211 168 ha. Currently the flora of the Norsky Nature Reserve is studied in details. A species list has been published and an analysis of the flora has been made (Starchenko, Chuvasheva, 1993; Veklich, 2009). The vegetation cover is poorly studied; so far no geobotanical map of the Reserve has been compiled. Only the overview map (scale 1 : 2 500 000) of the vegetation of the Amur basin (1969) gives an idea of the vegetation as a whole.
The climatic characteristics of the territory and the complex relief determine the diversity of plant habitats and their communities. The climate of the Norsky Reserve is continental with monsoon features and even ultracontinental (after A. I. Kaigorodov (1955). The modern relief of the Reserve includes wide floodplains of Nora and Selemdzha rivers, accumulative delta-terraces plain, Norskaya accumulative denudation plain (Geomorphologiya..., 1973) and hills.
According to the latest botanical and geographical zoning of the Amurskaya oblast, the Norsky Reserve belongs to the Mamynskiy and Ulmsko-Aldikonskiy districts of the Turan-Mamyn province of the Manchurian subdistrict of the East Asian area (Borisova,Starchenko, 2018). The province belongs to southern taiga with some elements of nemoral forests (Quercus mongolica, Tilia amurensis and etc.) along the valleys of Selemdzha River and its major tributaries. The southern taiga includes different larch forests (often disturbed), derived birch-larch forests with Pinus sylvestris, Picea ajanensis and Abies nephrolepis. The presence of nemoral species in forest cenoses increases in the direction from north to south. A province peculiarity is the wide distribution of larch peatmoss forests, swamps and wet meadows.
The scientific-reference typological map of vegetation on a medium scale (1 : 300 000) was compiled for the Norsky Nature Reserve for the first time. It shows spatial patterns of vegetation distribution in connection with the natural features of the territory (Fig. 5). The vegetation map legend is based on an ecologic and phytocoenotic classification. A zonal distribution of plant communities is presented in the legend. Plant communities are divided into some categories: dark-coniferous, light-coniferous and derived forests, which are represented as formations. The main cartographic units are groups of associations and their various combinations. The legend shows the vegetation of floodplains, rocks, and disturbed areas. Vegetation divisions are represented on the vegetation map by seventeen colors and one extra scale sign. All symbols have their own serial number, which is marked in the map legend.
The largest areas on the territory of the Reserve are occupied by larch forests — 42 % (Fig. 6). The forested territory as a whole occupies 36.5 %, of which the largest areas are rhododendron larch (9.7 %) and floodplain (9.5 %) forests. Ledum larch and moss-shrub forests occupy 5.7 %. Larch mixed-grass-shrub forests cover some small areas (2.0 %). Sub-taiga larch forests with nemoral grasses and often with oak and black birch trees occupy 0.6 %. Pine and larch-pine forests extend 1.3 % of the Reserve’s area. Fir-spruce forests on watersheds have limited distribution — about 1 %. They are a chain of ecologic-dynamic series on floodplain occupying 2.7 % of the Reserve’s area. To conclude, the vegetation cover of the Norsky Nature Reserve reflects the zonal and provincial features of the territory.
The phytosociology of the western section of Borakalalo Nature Reserve
