Microscopis fungi of Technosols in cities of different climatic zones

Among the high diversity of urban soils, of particular interest are soil constructures (Technosols) created by man to solve certain problems: landscaping and recultivation. Microorganisms quickly respond to external influences and are indicators of changes occurring in ecosystems. Microfungi determine the soil health, and the activity of saprotrophic microscopic fungi can lead to improved soil properties associated with soil fertility.

The aim of the study was to evaluate the quantitative indicators of soil fungal communities of 2-years-old Technosols, created on the basis of peat, sand and loam, in different climatic zones in comparison with background soils.

The studies were carried out in cities located in different climatic zones: subarctic (Apatity), temperate continental with a humid climate (Moscow), and temperate continental with a dry climate (Rostov-on-Don). Soil sampling was carried out at stations with soil constructures of a composition universal for all regions: peat/sand/loam in the ratio 1/1/1.

Quantitative assessment of the content of ribosomal genes of fungi was performed by real-time polymerase chain reaction (PCR). The fungal biomass was determined by luminescence microscopy method.

The predominance of fungal biomass over that of prokaryotes was revealed in all climatic zones, both in background soils and in Technosols. The fungal biomass in Technosols of different climatic zones varied from 0.073 to 0.790 mg/g of soil. In Apatity and Moscow, its values 2 years after the creation of Technosols were lower than in the background soil; in Rostov, the values were close. In the Technosols of Apatity and Moscow, microfungi were mainly in the form of mycelium, while in Rostov-on-Don, spores prevailed over mycelium. However, small spores prevailed in all zones, both in background soils and in Technosols. Over the 2-years period of Technosols development in the subarctic and the temperate zone, similar trends in the state of the fungal community were noted, while in the area with a warmer climate, other patterns were revealed.

The number of the fungal ITS rRNA ribosomal genes copies in the soils varied from 5.95×10⁸ in the Technosols of Apatity to 3.39×10⁹ gene copies/g soil in the background soil of the Moscow region. According to the quantitative content of fungal genes copies over a two-year period, the Technosols of Rostov-on-Don correspond to the background soils and slightly exceed the values of the latter. In the subarctic, the values of this indicator are also comparable for Technosols and background soils, while in Moscow, the number of copies of Technosols genes is 2.5 times less.

Thus, the change in the quantitative indicators of soil fungal communities over time makes it possible to judge the dynamics of the development of Technosols in different climatic zones. However, for such a short period (2 years), the state of fungal communities does not reach the state of the background ecosystems in any of the regions. We can only talk about trends in the parameters of the fungal community in the direction of background ecosystems.