Kaybasovo Poplar Forests (the Ob River, Tomsk Oblast, the Southern Taiga Subzone)

The Ob River basin is the last large fragment of the range of native Euro-Siberian poplar (Populus nigra, Populus alba) forests where these forests remain intact. The taiga section of the Ob River is occupied by the association Anemonidio dichotomi-Populetum nigrae Taran 1993, and the subtaiga, forest-steppe, and steppe sections are occupied by the association Equiseto hyemalis-Populetum nigrae Taran 1997. The purpose of the study is to determine the syntaxonomic status of poplar forests growing at the junction of the southern taiga and subtaiga subzones and to provide a detailed bryofloristic characterization thereof. Based on the Braun-Blanquet approach, we studied poplar forests located near the south border of the Ob River southern taiga section (Krivosheinsky district, Tomsk Oblast, Russia, surroundings of the Kaybasovo research station, 57º14′44″N, 84º11′05″E). In the forests, average species saturation by vascular plant species is 32.3 species per 100 m2, and its range is 13–56 species/100 m2. Moss flora includes 51 species. Average species saturation by mosses is 15.4 species per 100 m2, and its range is 10–21 species/100 m2. Based on the new data, total moss flora of the Ob poplar forests has increased from 73 species to 86 species and 1 variety (by 19 %), moss flora of the poplar forests of the taiga zone – from 59 species to 81 species and 1 variety (by 39 %). We identify Kaybasovo poplar forests as the new variant, Stellaria bungeana, of the subassociation Equiseto hyemalis-Populetum nigrae betuletosum pubescentis Taran 1997 (Equiseto hyemalis-Populion nigrae Taran 1997, Salicetalia purpureae Moor 1958, Salicetea purpureae Moor 1958)

Association Carici juncellae-Salicetum rosmarinifoliae (Alnetea glutinosae) on the south taiga section of the Ob River floodplain

The Carici juncellae–Salicetum rosmarinifoliae Korolyuk et Taran in Taran 1993 association (Salicion cinereae, Salicetalia auritae, Alnetea glutinosae) includes the communities of the shrub (Salix rosmarinifolia, S. cinerea)-birch (Betula pubescens) tussock (Carex juncella, C. cespitosa) mires spread on the big West Siberian river floodplains within the taiga zone. On the Ob River, the association is represented by the C.j.–S.r. spiraeetosum salicifoliae Taran 1993 subassociation. Its range covers the Ob floodplain 830-kilometer distance crossing the subtaiga, south taiga and middle taiga subzones of Western Siberia. In the south taiga subzone (surroundings of the former village Kaibasovo, Krivosheinskiy district of Tomsk Region, 57º14'44"N, 84º11'05"E), the C.j.–S.r. spiraeetosum salicifoliae subassociation is studied for the first time. Near the Kaibasovo, the subassociation is represented by two facies: shrubby (Spiraea salicifolia, Salix rosmarinifolia, Salix cinerea) and birch (betulosum pubescentis). The communities of these facies found some floristic differences, which made it possible to attribute them to different variants: var. Cicuta virosa and var. Kadenia dubia. Carex juncella, C. cespitosa and Comarum palustre dominate in the field layer of the tussock mires. In the C.j.–S.r. spiraeetosum salicifoliae subassociation communities near the Kaibasovo, the average total projective cover (TPC) of the tree layer is 7%, shrubs – 34%, grasses – 48%, tussocks – 20%, ground mosses – 14%. Average tussock height is 59 cm. Average species saturation of the communities is 27 species of vascular plants and 18 species of mosses per 100 m2, the volume of the local coenoflora is 39 species of vascular plants and 28 species of mosses. Six moss species (Brachytheciastrum velutinum, Bryoerythrophyllum recurvirostrum, Bryum moravicum, Fissidens bryoides, Plagiomnium cuspidatum, Pylaisia selwynii) were found in the Ob communities of the C.j.–S.r. spiraeetosum salicifoliae for the first time. Due to this, the total volume of the moss flora of the subassociation Ob stands increased to 74 species. The analysis of the variability of the main coenotic and floristic parameters of the C.j.–S.r. spiraeetosum salicifoliae subassociation in the geographical space of the Ob floodplain (from the subtaiga subzone to the middle taiga one) is carried out. The main regularities of these shifts are revealed. The volume of the subassociation local vascular coenoflora (52-53 species) and average species saturation of the communities by vascular plants (20-21 species per 100 m2) are stable on the most of the Ob floodplain sections. At the same time, changes are observed downstream of the Ob River, which can be interpreted as an intracoenotic response of the subassociation communities to smooth changes in the ecological regime of the floodplain when moving in geographical space from south to north. Thus, from the south to the north, many average parameters increase in the subassociation communities, namely: the height of trees, TPCs of tree layer, tussocks and ground mosses, the species saturation with mosses (from 4 to 18 species per 100 m2). The species richness of local moss floras also increases from 11 to 54 species. On the contrary, the average TPCs of shrub and field layers from south to north decrease. A number of deviations from general trends were found in the Kaibasovo birch-shrub tussock mires, namely: high species saturation with vascular plants (27 species per 100 m2), low reach of vascular coenoflora (39 species). The first can be explained by the proximity of the studied mires to the Ob riverbed, the second – by the crowding of the relevés in a relatively small area of the floodplain.

Rare component as an indicator of human flora transformation

This paper discusses the use of the rare flora component of Melekessky-Stavropol landscaped area as an indicator of anthropogenic transformation. The paper contains an ecological-floristic zoning of Melekessky-Stavropol landscaped area (lowland Trans-Volga) and the value of anthropogenic stress factors for each elementary floristic subarea and for the landscape area as a whole. The factors value due to non-equivalent sub-areas and lack of research is formalized and pointed. Relative factors values are compared to the total factor value for the landscape area. Rare flora component was studied and rarity species saturation was calculated, i.e. their number per unit area for each of the elementary floristic sub-areas. The authors revealed the dependence of rarity species saturation on the level of anthropogenic load in elementary subareas - the higher the rarity species saturation, the less anthropogenically transformed flora. A corresponding graph is presented and described in detail that makes it possible to estimate the anthropogenic transformation of flora, not only its active, dynamic components - alien flora, but also the degree of preservation of rare species.