Home – Home – Jornals – Contemporary Problems of Ecology 2017 number 5

The analysis of Trans-Urals (the Bashkortostan Republic) steppes has been carried out using 428 relevйs. Groups of species indicating position of plant communities on moisture and stoniness gradients were defined. We used ANOVA-based technique of definition of indicator species groups. The role of indicator species in diagnostic combinations of Trans-Urals steppe syntaxa was determined.

Perpendicularity of solar rays incidence on land surface, termed slope insolation, is calculated as non-linear function of slope steepness and exposure. This variable better describes light and thermal regime of slopes. We demonstrate that grass cover insolation can be evaluated from slope insolation and tree crown closure. It was found for a terrain at the southern boundary of the forest-steppe that species richness and green mass of herbage were closely related to topography and insolation (R² = 0.77 and 0.83, respectively), and crown closure - to topography and slope insolation from the south (R² = 0.85). Soil moisture was in general negatively related to slope insolation. A critical level of crown closure (15 %) was determined, the limiting factor for herbaceous plants was soil moisture below this level, and light was above it. Grass cover insolation close to its average value (400 W/m²) differentiated phytocoenotic characteristics onto areas of increased and diminished values.

Radial growth of the Scots pine growing in the forest-steppe zone of Western Transbaikalia on five sites was studied. For each site additional samples were collected, which allowed to increase reliability and build two regional chronologies. The analysis of correlations between chronology and such factors as monthly temperatures, precipitation and Selyaninov hydrothermal coefficient was performed. The analysis of a 10-day moving climatic series made it possible to clarify the periods of climate impact on growth: the basic limitation of pine growth in the region was observed by moisture availability, including conditions during the previous (from late July to late September) and current (May-mid-July) vegetative season. Also fluctuations of 23-35 years in the dynamics of climatic factors and radial growth of the pine were revealed.

A climate-related shift in the range boundaries of the western central asian subboreal species Melanargia russiae in the Urals region from the northern forest-steppe zone to the pine-birch forests was found. Morphological variation of M. russiae wings from the marginal northern populations and populations from the main part of the range in the Urals was studied. The results of the morphological traits (size, wing shape, wing pattern eyespots) complex analysis confirm the hypothesis of the local population formation in the south of the Sverdlovsk region and contradict the hypothesis of the migratory origin of M. russiae imago.

The changeability of seasonal molting completeness of the passerine birds of tundra and forest-tundra of Western Siberia is examined. There are all known variants of passerine molting in North Eurasia - from the complete postjuvenile molting at the places of birth from eggs to its absence and complete postjuvenile molting at the places of wintering or on the ways of migration, from the complete preconnubium molting at the places of wintering to its absence, from complete post-nuptial moult on the breeding grounds to complete molt on the wintering grounds or migration paths. The factors affecting the completeness of moult - features of the development of the subarctic, the length of the migratory route of the photoperiodic conditions during molting are discussed. The greatest influence on the completeness is exerted by the duration of daylight.

Two fungal-like organisms (class Oomycetes) and 263 species of fungi from 111 genera, 42 families, 23 orders and 7 classes in the territory of the nature reserve Aksu-Zhabagly were found. Twenty two species were found for the first time. The vast majority of species are parasitic (202 species), 56 belong to saprotrophs and 7 - to symbiotrophs. The classes Taphrinomycetes, Urediniomycetes and Ustilaginomycetes are presented exclusively by parasites. The class Ascomycetes has 21 species of saprotrophs, 27 parasites and 4 symbiotrophs. From the class Basidiomycetes the largest group of humus saprotrophs has 15 species, litter saprotrophs and parasites - 4 species each, symbiotrophs - 3 species, coprotrophs and xylotrophs - 2 species each, litter and humus saprotrophs - 1 species. Anamorphic fungi are represented by 91 parasitic species and 11 saprotrophs. In comparison with closely spaced Sairam-Ugam national park and the Karatau nature reserve mycobiota of Aksu-Zhabagly is characterized by a significant number of species from the classes Basidiomycetes, Urediniomycetes, Hyphomycetes and Coelomycetes. Thirty one species are common to these protected areas. The most numerous group of them are parasites.

Features of formation of soil fauna under 40-year coniferous and deciduous cultures created in identical climatic and edaphic conditions of southern taiga of Middle Siberia are considered. It is shown that the main distinctions in structure, density and biomass of soil invertebrates are caused by formation of a forest floor. For the first time by means of the bait-lamina test dependences of trophic activity of soil biota on density and biomass of invertebrates have been received.

Abundance, biomass, production and size-morphological structure of heterotrophic bacteria were determined and their contribution to the total plankton biomass was evaluated in the Rybinsk reservoir (the Upper Volga) during the ice-covered period. Structural and functional characteristics of bacteria, except for their cell sizes in winter were lower than those in the growing season. However, heterotrophic bacteria contributed mainly (89.3 %) to the total biomass of plankton community in winter. During the growing season phytoplankton was a major component of the plankton (48.8 %), while the bacteria averaged 36.5 %. The total plankton biomass under the ice averaged 148 mg C/m³ that was 2.6 times lower than in the period of open water. During the ice-covered period the number of protists was small and they consumed an insignificant part of the bacterial production, and the viral lysis was the main reason of the bacterial mortality.

The quantitative and qualitative diet features of the rodent species in arid conditions on the Terek-Kuma Lowland were studied. Species composition, shares and diversity of foods in diets of rodent species were revealed. Diets of rodent species consisted of many plants species. Meriones tamariscinus diet consisted of 29 plant species, M. meridianus diet consisted of 40, Cricetulus migratorius diet consisted of 26, Sylvaemus fulvipectus diet consisted of 34 and Mus musculus diet consisted of 30 plant species. Dietary overlap between rodent pairs was from lower to middle.

We provide a quantitative analysis of post-outbreak wildfire frequency within the confluence of the Yenisei and Angara affected by the Siberian silkmoth (Dendrolimus sibiricus Tschetv.). That catastrophic outbreak was observed in 1993-1995, extended for about one million ha and caused stands mortality in the area of about 460 thousands ha. For outbreak area the fire frequency was about 7 times higher compared to the reference, burned area - 20 times higher. The peak of fire activity within outbreak areas occurs in May - June, while that for undamaged coniferous stands - in July. The number of fires is correlated with the average monthly (June) air temperature ( r = 0.65). The area of fires has a negative correlation with the moisture conditions: precipitation ( r = -0.53), drought index (SPEI: r = -0.57), and ground cover moisture content ( r = -0.57). Extensive fires prevail within outbreak areas ( S > 1000 ha), while within control - smaller area fires. The multiple (re-occurred) wildfires are typical of pest outbreak area. The area of these fires is related to their re-occurrence by logarithmic dependency (17 % of the territory burned by forest fires twice, 5 % - three times, and 0.5 % four times). Wildfires in outbreak areas hinder initial forest recovery by destroying regeneration of coniferous: 20 years after the outbreak >90 % of disturbed areas are occupied by the grass-bush and small-leaved cenoses.

On the basis of long-term (1995-2010 and 2013-2014) microbiological monitoring of the various water areas of the Volga Delta and perch pelagic predator, four dominant groups of bacteria Enterobacteriaceae, pp. Aeromonаs, Flavo, Pseudomonаs were identified. Summarizing results of studies of species composition of microflora of water and fish from natural populations and artificial breeding are given. It was established that conditionally pathogenic microflora in the water and fish prevailed over the indicator one. The role of water temperature governing the seasonal cycles of microorganisms and pathogenicity factors that determine their fast adaptation to living in different ecological niches is shown.