Том 50, № 1 (2017)

This study was carried out in alien warmth-tolerant forest plantations of red oak (Quercus rubra), common beech (Fagus sylvatica) and European larch (Larix decidua). We compared the changes in foliar litterfall mass and biochemical composition after five months of cold period. The mean mass of fresh foliar litterfall collected in late autumn was 30% higher in red oak compared to the larch and beech plantations. After the cold period, the reduction of foliar litterfall mass did not exceed 10% in any of the studied plantations. The fresh foliar litterfall of red oak was the richest in cellular fibre and easily decomposable glucose and nutrients such as P and Mg, larch was distinguished by the highest lignin, N, K and Ca concentrations, while beech fresh foliar litterfall was the poorest in the aforementioned nutrients. After the cold period, the changes in the biochemical composition of foliar litterfall revealed different patterns. In the spring, the beech and red oak foliar litterfall was the richest in N, P and Ca, meanwhile the larch foliar litterfall still had the highest concentration of lignin but, in contrast to the autumn, was the poorest in nutrients. After the cold period Lignin: N, C: N and C: P ratios reached critical values indicating that the foliar litterfall of beech and red oak had started to decompose. The highest lignin concentration and the highest and most stable Lignin: N, C: N, C: P and N: P ratios after the cold period indicated that the slowest foliar litterfall decomposition took place in the larch plantation.

Concentrations of heavy metals (HMs) were determined in soils of the eastern coast of the Northern Sakhalin Lowland. The total contents of HMs and their distribution in the studied soils differed from those in the world soils. Thus, barium and mercury concentrations exceeded clarke values for the world soils. The reserves of mobile forms of microelements were found to be low. Significant biogenic accumulation in organic soil horizons in the process of soil formation was found for copper, arsenic, and barium.

Bioassay and biosorption potentials of different groups of cyanobacteria (CB)—Nostoc linckia (Roth.) Born. et Flah. No. 271, natural biofilms dominated by CB of Phormidium genus, and biofilms dominated by Nostoc commune (Vauch. Elenk)—were estimated. The physiological-biochemical response of CB to the influence of copper sulfate (II) (catalase activity with a gasometric method and dehydrogenase activity, lipid peroxidation, and chlorophyll ɑ and pheophytin contents with a spectrophotometric method) was studied; metal bioaccumulation was determined with a stripping voltammetry method. It was found that the communities dominated by Phormidium genus (CB biomass 0.2 g/dm³) removed copper compounds from the solutions with Cu²⁺ ion concentration of 20 mg/dm³ almost completely (by 99%); communities dominated by CB N. commune, by 87%; and pure culture of N. linckia, by 50%. Dehydrogenase and catalase activities and the intensity of bioluminescence proved to be sensitive indicators of the response of CB to Cu²⁺ ions. The impact of Cu²⁺ ions (20 mg/dm³) on a biofilm dominated by CB of Phormidium genus resulted in the fivefold decrease of catalase activity during 24 h; dehydrogenase activity decreased by nearly 357 times. The bioluminescence intensity during 24 h decreased by 1.3–100 times under the impact of Cu²⁺ (2 mg/dm³) and by 8.6–200 times in variants with a higher concentration of Cu²⁺ (20 mg/dm³). This regularity can be used as a test function in bioassay.

Population density and biomass of microorganisms were studied in background soils and in soils affected by hydrogen degassing. These parameters were lower in the latter soils. Actinomycetes and fungal mycelium could not be isolated from the soils treated with hydrogen already on the fourteenth day of the experiment; the number and biomass of fungal spores decreased to zero levels even earlier, on the seventh day. Fungi represent a specific physiological group, and their capacity for environmental adaptation is much lower than that of bacteria.

The Late Holocene stage of forest pedogenesis has been studied on the interfluves along river valleys in the forest-steppe zone of the Central Russian Upland. The development of gray forest soils from the former chernozems as a result of the Late Holocene advance of forest vegetation over steppes is discussed. It is argued that the climatic conditions of the Subatlantic period were unstable, so that multiple alternation of forest and steppe vegetation communities took place. This specified a complex character of soil evolution upon contrasting substitution of forest pedogenesis for steppe pedogenesis. On the interfluves near the natural drainage network (balkas, ravines, and steep slopes of river valleys), the climate-driven dynamics of forest and steppe vegetation with corresponding changes in the character of pedogenesis could take place during the entire Holocene, which is reflected in a lower thickness of humus profiles and deeper leaching of carbonates from chernozems of the Early Iron Age in comparison with their analogues formed under steppe cenoses in central parts of the interfluves. Two variants of the evolution of gray forest soils can be suggested: the pulsating evolution typical of balkas and interfluves near river valleys and the continuous progressive evolution typical of automorphic (plakor) positions in central parts of the interfluves.

The relationships between the morphometric parameters (MPs) of topography calculated on the basis of digital elevation model (АSTER GDEM, 30 m) and the properties of the plow layer of agrogray soils on a slope were analyzed. The contribution of MPs to the spatial variability of the soil moisture reached 42%; to the content of physical clay (<0.01 mm particles), 59%; to the humus content, 46%; to the total nitrogen content, 31%; to the content of nitrate nitrogen, 28%; to the content of mobile phosphorus, 40%; to the content of exchangeable potassium, 45%; to the content of exchangeable calcium, 67%; to the content of exchangeable magnesium, 40%; and to the soil pH, 42%. A comparative analysis of the plow layer within the eluvial and transitional parts of the slope was performed with the use of geomorphometric methods and digital soil mapping. The regression analysis showed statistically significant correlations between the properties of the plow layer and the MPs describing surface runoff, geometric forms of surface, and the soil temperature regime.

The long-term dynamics of the anthropogenic soil solonetzicity under the impact of applied deicing salts were studied in the Eastern administrative okrug (EAO) of Moscow. The composition and amount of the applied agents and distribution patterns of sodium in snowmelt water and in soils of different land-use zones were analyzed. The maps of soil solonetzization in the EAO in 1989, 2005, and 2010 were compiled, and the degree of degradation of the soil cover was evaluated. It was shown that the contrast of the technogenic anomalies in the content of exchangeable sodium and the size of these anomalies in soils of the okrug increase with time. In 21 years, the mean content of exchangeable sodium in the surface soil layer increased from 0.38 to 0.80 cmol(equiv.)/kg, and the degree of solonetzicity (as judged from the exchangeable sodium percentage) increased from 3.1 to 7.2%. In 2005–2010, the rates of sodium accumulation in the soil adsorption complex were twice as high as those in 1989–2005.

The feeding activity of soil saprophages was assessed by the bait-lamina test in pine forests of native origin within the city of Yekaterinburg and its suburbs in 2011–2013. Four areas, drastically different in terms of manifestation of two main factors—urbanization and recreation loads—were compared. The effect of urbanization on the feeding activity of soil saprophages was both positive and negative. Recreation loads, as a rule, adversely affected the feeding activity. Probable mechanisms responsible for the influence of a large city environment on the feeding activity of soil saprophages are discussed.