BSCs are common in arid and semiarid regions where vascular plant cover is naturally sparse, maximizing the exposure of surface-dwelling organisms to direct sunlight. Most of these physicochemical properties are known to stimulate the growth of algal cells, however no evidence has been found in this study regarding the relationship between 137Cs activities in soil and the algal species richness.Д«iological soil crusts (BSCs), or biocrusts, are composed of fungi, bacteria, algae, and bryophytes (mosses, etc.) that occupy bare soil, entwining soil particles with filaments or rootlike structures and/or gluing them together with polysaccharide exudates to form a consolidated surface crust that stabilizes the soil against erosion. Soil algae play an important ecological role in sustaining terrestrial ecosystems and are sensitive to various physicochemical properties of soil, such as pH level, nutrient content and moisture. In the forest burnt by the crown fire, where the above ground vegetation was almost completely destroyed, the mobile fractions of 137Cs are easily washed out from the topsoil, allowing them to penetrate into deeper soil layers. The forest soil affected by surface fire is characterized by an increased amount of easily exchangeable and mobile fractions. The proportions of various 137Cs fractions, according to our findings, differ between fire-affected and unburnt forest soils, and also between the different types of wildfire.

The soil samples were analyzed for radioactivity, agrochemical characteristics and the abundance of photoautotrophs. Soil samples were collected in 20 from sites burnt by surface and crown fires, and from two unburnt reference locations. The aim of the study was to explore the effects of different types of wildfires on the biological availability of radionuclides and the distribution of algal communities in fire-affected soils. This study was carried out in the forest area of the Gomel region of Belarus contaminated by 137Cs following the Chernobyl accident of 1986.

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