Vol 50, No 5 (2019)

The α-diversity of the grass layer was compared for communities exposed to Acer negundo and unexposed communities. The communities were aligned by characteristics by their degrees of urbanization, fragmentation, and anthropogenic disturbance. The research was carried out in the city of Yekaterinburg (the southern taiga subzone, Russia) at 13 sites. Each site included two sampling plots: one in communities dominated by A. negundo and the other in communities dominated by other tree species (total of 26 communities). It is established that the key factors of variation in the grass layer characteristics are the dominant tree species (A. negundo or other trees) and the stand area. The number of grass species per 400 m² was lower in A. negundo thickets than under the crowns of other trees: 17 ± 3 and 28 ± 3, respectively. However, communities with and without A. negundo did not differ in the values of the Shannon index, the degree of dominance, or the ratios of annual/perennial and graminoid/forb species. An increase in the degree of habitat fragmentation was accompanied by an increase in the proportion of synanthropic species, both under the canopy of A. negundo and in communities dominated by other trees. Methodically, the results showed that assessment of the consequences of plant invasion should always take into account the spatial patterns of determination of the structure of communities.

Within the ecotone of the upper limit of woody vegetation on the southeastern macroslope of the Khibiny Mountain ridge (Kola Peninsula), the spatial and age structure, as well as features of the phytomass accumulation of spruce–birch stands, were studied. Analysis revealed that there was a manifold increase in the density and productivity of forest stands in the last century, and the upper border of the woodlands and dense forests has moved considerably higher into the mountains. All of this happened against the background of an increase in early summer temperatures and a longer growing season in the area in the 20th century. Our data will help simulate the response of mountain ecosystems in the region to future climate change.

The dynamics of radial wood increments have been analyzed according to the three tree-ring chronologies ALT (1463–2017), TUV (1715–2012), and MON (1663–2017) obtained for the southern regions of the Altai Mountains, southwestern regions of Tuva, and northern regions of Mongolian Altai, respectively. Chronologies demonstrate similar annual and long-term temporal variability. Cyclic changes in wood growth with periods of 10–14 and 29–33 years have been revealed. The limiting factor of growth is the air temperature in June–July (r > 0.7). At the same time, the chronologies are sensitive to the variation in circulatory, hydrological and glaciological parameters.

The aim of the study was to verify a hypothesis that the proximity of different ecosystems have an impact on the richness of flora in three forest patches in the Choszczno Forest Inspectorate (West Pomeranian Province in NW Poland). Between 2013–2015, the survey involved three areas with different adjacent ecosystems: forest, built−up area, and grassland. At each object we analyzed four test plots consisting of inner, middle and outer zones. The composition of tree, shrub, herbaceous, moss and lichen species was determined in each object, plot and zone. It was shown that adjacent ecosystems influenced the richness of flora in the analyzed forest areas. Differences in the numbers of species and in their habitat affiliation were also found between ecotone zones. The outer ecotone zone had the richest flora composition, particularly in terms of grassland species – present in 12 zones of all three objects.

The article presents long-term (from 1996 to 2018) data on the distribution of burbot larvae at the endogenous-feeding stage during downstream migration in a stream of spawning tributaries of the Ob River: the Severnaya Sosva River (16 years of observations), the Sob River, and the Voikar River (one year of observations). The assumption that the predominance of larvae in the flow horizons depends on the flow velocity has not been confirmed; the distribution depends on the developmental stage. Based on the Spearman correlation and the Mann-Whitney criterion, the developmental stage of downstream migrating larvae at the control point, mediated by the distance of downstream migration, is shown to depend on the maximum level of floodplain flooding per year of prespawn migration of the spawners. Before the start of the physiological functioning of the swimming bladder, juveniles are more common in the lower horizons of the stream; after the start, they are more common in the upper ones. Immediately after hatching, due to the presence of a rheoreaction and negative geotaxis, the larvae use their muscles to enter the zone of active turbulence, which is the main factor contributing to their maintenance in the water column in the first three days of life.

The features of the spatial distribution of four species of Mouse-Like rodents (Sylvaemus fulvipectus, Cricetulus migratorius, Microtus socialis, and Dryomys nitedula) in the forest associations of the foothill zone of the Republic of Dagestan are analyzed. Sixteen environmental parameters are selected, of which ten significantly showed interspecific differences. The distribution of rodent species is demonstrated relative to the environmental characteristics taken into account in the descriptions; the preferences and requirements for the environment of each species are revealed. Thus, the yellow-bellied mouse and gray hamster were found at all stations, whereas the forest dormouse and social vole were more selective in their choice of stations. As a result, the width of the spatial niches for the yellow-bellied mouse and gray hamster is greater than that of the forest dormouse and social vole. The results of pairwise comparison of the spatial niches of studied rodent species reveal low values of their overlap.