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Fires are predicted to increase in Arctic regions due to ongoing climate change. Tundra fires can alter carbon and nutrient cycling and release a substantial quantity of greenhouse gases with global consequences. Yet, the long-term effects of tundra fires on carbon (C) and nitrogen (N) stocks and cycling are still unclear. Here we used a space-for-time approach to investigate the long-term fire effects on C and N stocks and cycling in soil and aboveground living biomass. We collected data from three large fire scars (>44, 28, and 12 years old) and corresponding control areas and used linear mixed-effect models in a Bayesian framework to analyse long-term development of C and N stocks and cycling after fire. We found that tundra fires had no long-term effect on total C and N stocks because a major part of the stocks was located belowground in soils which were largely unaltered by fire. However, fire had a strong long-term effect on stocks in the aboveground vegetation, mainly due to the reduction in the lichen layer. Fire reduced N concentrations in graminoids and herbs on the younger fire scars, which affected respective C/N ratios and may indicate an increased post-fire competition between vascular plants. Aboveground plant biomass was depleted in 13C in all three fire scars. In soil, the relative abundance of 13C changed with time after fire. Our results indicate that in lichen-rich subarctic tundra ecosystems, the contribution of fires to the release of additional carbon to the atmosphere might be relatively small as soil stocks appear to be resilient within the observed time frame.

The post-anthropogenic and soil cover transformations of former agricultural soils on the abandoned lands in the Russian Arctic territory are poorly investigated due to the active growth of the city complexes and increasing area occupied by agricultural lands. That is lead to an increase in the area of the arable lands surrounding the polar urbanized territories. Today, most of that land allocated for agricultural needs has been abandoned or affected by other types of land use. This study aimed to investigate the abandoned lands surrounding some of the settlements in the central part of the Yamal region. The soil diversity, morphology, and chemical and agrochemical properties were investigated with special reference to the specific transformations that occur to fallow lands under permafrost-affected cryogenic-ecosystem conditions. Analysis of data show that these soils are characterized by features relating to both, previous (and existing), anthropogenic impacts and natural processes such as cryogenic mass transfer. The degradation of the arable humus-enriched horizon was not as pronounced as it has been in more humid boreal environments over recent decades. The organic carbon content in topsoil depends on the land use and varied considerably among the soil types. The former arable topsoil horizon has been stable over time in terms of its morphological features and agrochemical state. Despite the high soil acidity levels, thenutrient content in the anthropogenically impacted soils was still high, even though being abandoned for 20 years.

The flora of two towns and two settlements in the northern taiga and forest-tundra of Northwest Siberia (Russia) are considered. Urban species lists are limited (61–119 vascular plant species) and mainly consist of native species with a predominance of perennial herbs. Various urban functional zones (industrial, residential, recreational, vegetable patches) differ by species composition, and this difference increases in the course of city development. In the industrial zone, vegetation composition is closer to the native flora, because of the low number of adventive species. Maximal diversity is due to decorative plants, cultivars and southern weed distribution, and is typical to residential neighborhoods. Species diversity increases mainly because of woody plants introduction. Alien species are represented generally by a small number of individuals. The severe climate and poor soils limit their abilities to spread in the Far North. Urbanization forces the reduction of aboriginal biodiversity, but in northern areas where native species have the adaptive advantage, this effect is minimal. Changes in flora since 1995 were analyzed in the town of Novy Urengoy (Yamalo-Nenets Autonomous Okrug, Russia). Plant diversity increased by about 20 % in all functional zones, although some alien and natural species were not recorded in 2018.

Dynamically developing urbanization causes a number of environmental effects, including those related to the chemical transformation of soils. Relatively less information about the urban areas of the Arctic and Subarctic zones, constructed mostly on permafrost and intensively populated areas can be found. By the example of the analysis of basic soil properties and concentrations of trace metals in the soils of the cities of Salekhard, Urengoy, Nadym, Novy Urengoy and Gaz Sale (the Yamalo-Nenets Autonomous District), as well as various functional zones within the cities, the relationship between the age of the cities, the level of anthropogenic pressure and the type of parent materials and the character of accumulation of metals in the soil profile of urban soils have been described. The direct correlation was found between the content of Pb, Cr, Ni, As and soil sorption characteristics. In young cities built on sandy sediments, there is less accumulation of heavy metals in the topsoil horizons. Relatively higher concentrations of Cu and Cd were noted in soils of industrialized cities, regardless of functional zones. The higher content of Cr, Ni, Cu, Zn, As and Pb has been registered in older zones also frequently used for residential purposes. The calculated values of the PI index for some functional zones of young cities show the medium and high content of heavy metals. The analysis of Igeo and PLI indices shows a large diversity both in relation to individual cities and their functional zones. Soil quality, in spite of the high level of anthropogenic load, was assessed as mostly satisfactory.