Specific Features of Soil-Vegetation Cover of Revegetated Oil-Polluted Oligotrophic Bogs Reclaimed by the Cutting Method in the Middle Ob Region

Abstract

The article provides data from a comparative analysis of vegetation restoration in areas of oligotrophic bogs with strong oil product pollution located within an oil field in the Middle Ob region reclaimed according to standard schemes widely used in the 2000s and by cutting off oil-contaminated soil. The total projective vegetation cover (TPVC) of all reclaimed areas mostly reaches standard values (above 30%). The TPVC in areas without cutting is slightly higher than in areas with cut off contaminated soil due to greater restoration period in the former. The mean number of all recorded species in areas with cutting is slightly higher, and there are some oligotrophic vascular plants among them (heather shrubs, Drosera rotundifolia, and Eriophorum vaginatum), which much less frequently settle in areas without cutting. The projective cover of the herb–dwarf-shrub layer is higher in areas without cutting. The content of oil products in the surface 20-cm-thick layer in areas with cut-off polluted soil is generally lower as compared to areas reclaimed by traditional methods. However, even high concentrations (more than 250 g kg^–1) do not exert a significant negative effect on the total projective cover of the grass/herb–dwarf-shrub layer, while its minimal values are primarily associated with a lack of moisture on high microrelief elements. Similarly, high concentrations of hydrocarbons do not prevent the formation of moss cover dominated by sphagnum in areas of cut-off hollows. On the contrary, mosses of the genus Polytrichum and true mosses were much more sensitive to oil pollution in the form of bitumen crust, and thus avoided areas without cutting.