Urbanization Affects Soil Microbiome Profile Distribution in the Russian Arctic Region

Abstract

Urbanization in the Arctic results in considerable and still poorly known environmental consequences. The effect of urbanization on soil microbiome—an ecosystem component highly sensitive to anthropogenic disturbance—remains overlooked for the Arctic region. The research compared chemical and microbial properties of the natural Podzol soils and urban soils of Murmansk—the largest Arctic city. Particular attention was given to the profile distribution, which is almost completely ignored by most microbial studies. Soil microbiome was investigated by the quantitative indicators based on fluorescence microscopy (microbial biomass) and PCR real-time methods (amount of rRNA genes copies of archaea, bacteria, and fungi). The principal changes in urban soils’ properties compared to the natural references included a shift in pH and an increase in C and nutrients’ contents, especially remarkable for the subsoil. The numbers of rRNA genes copies of archaea, bacteria, and fungi in urban topsoils (106–1010, 109–1010, and 107–109, respectively) were lower than in Podzol; however, the opposite pattern was shown for the subsoil. Similarly, the total microbial biomass in urban topsoils (0.55–0.75 mg g−1) was lower compared to the 1.02 mg g−1 in Podzols, while urban subsoil microbial biomass was 2–2.5 times higher than in the natural conditions. Both for urban and natural soils and throughout the profiles, fungi were dominated by mycelium forms; however, the ratios of mycelium–spores were lower, and the amount of thin mycelium was higher in urban soils than in natural Podzols. Urbanization in the Arctic altered soil morphological and chemical properties and created a new niche for microbial development in urban subsoils; its contribution to biodiversity and nutrient cycling promises to become increasingly important under projected climate change.

The Microbiomes of Various Types of Abandoned Fallow Soils of South Taiga (Novgorod Region, Russian North-West)

“…This well corresponds with the data of another fallow soil experiment, which show that in a 25-year-old fallow plot of albic retisol, the intensity of microbiological processes was close to those in virgin soddy-podzolic soils (Retisols), which were used as a control [38]. The dominance of Acidobacteriota is known to be typical for organogenic and organomineral soil horizons [34]. Also, the dominance of Alpha-and Gammaproteobacteria, Actinobacteriota, Verrucomicrobiota, and Planctomycetota is known as typical for superficial podzol soil organic and organo-mineral horizons with acid reaction [8,37].…”

“…The lowest values of observed ASV, indicating community richness, were detected in the microbiomes of both forest soils-mature and 30-year-old forest on fallow land. The opposite data were obtained for the podzol soil microbiome under the urbanization effect [34]. It was previously shown that the composition of the microbiome of podzols was strongly influenced by the duration of the soil in a disturbed state [35]; in our case, several objects had one age of accumulation-30 years, which means that the microbiome is determined not by the age of the soil, but by the type of its use.…”

“…High levels of nitrifying Nitrososphaerota archaea and Nitrospirota representatives were present, indicating that the microbiome reacted sharply to the introduction of excess nitrogen into the soil. These data contribute to the hypothesis [34] that the age of soil disturbance may play the most important role in the diversification of soil microbial biodiversity. The representatives of Gemmatimonadota did not show any significant differences among the soils.…”

Wildfires’ Effect on Soil Properties and Bacterial Biodiversity of Postpyrogenic Histic Podzols (Middle Taiga, Komi Republic)

“…The analysis of the taxonomic composition of soil samples showed significant differences between the postfire soil and the control organic horizon (three horizons) already at the phylum level (Figure 8). It is known that the dominance of Acidobacteriota is characteristic of organogenic and organomineral soil horizons [86]. The dominance of Alphaand Gammaproteobacteria, Actinobacteriota, Verrucomicrobiota, and Planctomycetota is characteristic of surface podzol organomineral horizons with an acidic reaction [87].…”

Bacterial Communities: Interaction to Abiotic Conditions under Effect of Anthropogenic Pressure

“…Furthermore, changes in the dominant bacterial taxa and their interactions with other soil bacterial Sustainability 2023, 15, 11366 2 of 15 communities also alter the structure, function, and stability of microbial ecosystems [6]. Significant changes in soil bacterial communities' composition and functioning due to different intensity anthropogenic activity were associated with changes in soil pH and nutrient availability [7].…”