Tree stand dynamics, changes in the ground vegetation and soils, and species diversity of wood-decaying fungi were studied in pristine middle boreal spruce forests affected by a surface fire in the Vodlozersky National Park (Arkhangelsk Region, Russia) in 2011. In the third year after the fire, the burnt area was dominated by birch, which contributed an average of 72% to the total amount of major tree species regeneration. In sites affected by a high-severity fire, the ground vegetation cover did not exceed 40%, with Chamaenerion angustifolium (L.) Scop. and Marchantia polymorpha L. dominating in the first years after. By the tenth year, the diversity of the newly forming tree layer increased from 5 to 11 species and natural thinning of deciduous tree regeneration was already underway, although its amount was still over 100,000 plants per hectare throughout. By the end of the first post-fire decade, Picea abies (L.) H. Karst. and Pinus sylvestris L. accounted for 11% of the total regeneration. The occurrence and cover of pyrogenic species Chamaenerion angustifolium and Marchantia polymorpha declined sharply at this stage. Vegetation in sites affected by mid-severity fire was mostly regenerating through propagation of the survivor Avenella flexuosa (L.) Drejer, Vaccinium myrtillus L., V. vitis-idaea, etc. In the burnt area, the species diversity of wood-destroying fungi was reduced compared to the adjacent unburned areas, and it was the same in both heavily and moderately burnt areas. This is probably due to the fact that the downed deadwood in post-fire sites was trunks of the same age and in the same degree of decay whereas the total amount of downed deadwood in the control (unburnt forest) was lower but featuring all stages of decay and, furthermore, there were plenty of fungi-populated dead standing and weakened overmature trees.

It is shown that the chemical composition of the litter falls and wood of deciduous and coniferous trees is different. On the background of aerotechnogenic pollution, accumulation of individual heavy metals, an increase in ash content was noted. There was revealed the anthropogenic dynamics of the accumulation of heavy metals in the wood of trees: the maximum number during the period of diesel traction; as the railway site is electrified, the accumulation of elements decreases. The obtained data can be recommended to be used for phytoremediation at sites subject to pollution. The obtained data will be the basis for assessing the phytoextractive potential of woody plants, in diagnosing aero-technogenic pollution of the environment, solving the problem of reducing environmental risks, as well as during the modernization and planning of environmental measures in the field of railway infrastructure.

The study was carried out in blueberry pine forests of the middle taiga subzone of Karelia. The results of complex studies of the microbiocenosis of Al-Fe-humus soils (Albic Podzols) formed on fluvioglacial deposits are presented. The methods of luminescent microscopy and substrateinduced respiration were used to assess the carbon of microbial biomass (Cmic). To study the microbiological activity of soils in relation to the mineralization of soil organic matter, the basal respiration method was used, and the metabolic coefficient was calculated. It is shown that the changes in the studied indicators reflect the natural and climatic conditions and the specifics of the soil of Al-Fe-humus genesis. The highest values of Cmic and basal respiration were observed in the subhorizons of the forest floor, and the lowest in the eluvial and illuvial horizons. The results obtained can be used as microbiological indicators in modeling carbon cycling processes in Al-Fehumus soils of forest ecosystems.

The properties of a sandy Ferric Podzol over fluvioglacial deposits and the root mass of its 0–20 cm layer with Pinus sylvestris L. fine roots (≤3 mm in diameter) have been studied in a mid-taiga cowberry-type pine stand. Keeping in mind the structure of the phytogenic field of a tree, the study is subdivided into trunk, crown, and gap zones. The root mass of the forest floor and the mineral horizons are found to change in different directions in the these zones. In the forest floor, the trunk zone is more saturated with roots than the gap zone, while the trend in the soil mineral layer was the reverse. The highest root biomass is associated with sites that are the richest in soil nutrients and organic matter (NPKC). The cellulolytic activity and ecophysiological parameters of the microbiota vary in the studied horizons. Cellulolytic activity in the forest floor is the highest near tree trunks, while the spatial variation of this parameter in the mineral body of the soil is less pronounced. A correlation is detected between the contribution of root respiration to total СО₂ emissions from the soil surface and the biomass of fine roots (≤3 mm) in the 0–20 cm soil layer. The effect of the soil thermal regime on root mass in different zones of the phytogenic field is studied. Soil temperature variation due to the redistribution of solar energy by the canopy results in a higher root mass in areas receiving more heat. The zone with better heated soils is the canopy gaps. The effect of the temperature of the root mass of the soil is more explicit in the mineral layer. The results of this study can be used in environmental monitoring and in predictive assessments of the effects of climate change on boreal forest ecosystems.

This study was conducted on the territory of the national park Paanayarvi, located in the taiga zone of the European north. The altitude zone common in the territory of the national park is up to 350 m above sea level. The purpose of this work is to study the microbiological and biochemical properties of soils formed under conditions of a gradient of altitude zonation. This work was performed for the first time in this territory. Based on the fatty acid composition of the cell walls of microorganisms, the composition and structure of the microbial community were determined by chemato-mass spectrometry. The dominant microbocenosis of soils of undisturbed territories was revealed. Changes in prokaryotes and microscopic fungi in the gradient of the altitude zone occur in different directions, which is consistent with the work of other researchers. The results suggest that the formation of microbocenosis of soils located in different conditions of the phytocenotic environment depends on the location of the site relative to the height. The latter determines the flow of solar energy into the ecosystem and the hydrothermal regime of soils. The data obtained can be used in monitoring global climate changes, will become the basis for the formation of a general conceptual basis for the functioning of microbial communities of soils of low-mountain landscapes.