Soil catena complex of the river Dnipro Arena within the “Dnieper-Orilskyy” natural reserve

Abstract. Investigated polygon laid in the northeastern part of the “Dnieper-Orilskyy” natural reserve. Five test plots were laid within polygon. The most common moisture conditions within the explored catena meet meadow steppe regime. For most studied soil moistening the soil plays an essential role in the water regime. Groundwater was at a depth that exceeds the depth of the cut in chornozem-like pine-forest soil and in a sod-forest chornozem-like soil. In other soils, the water level was 155 cm in sod-forest chornozem-like soil, 98 cm in alluvial meadow soil and 83 cm or 135 cm in alluvial meadow marsh soils. The conditions of the salt regime can be attributed to the soils of the studied catena categorized as poor soils. The chornozem-like pine-forest soil has a wide range of variability salt regime, while the alluvial meadow marsh soil has a wide range of variability humidity conditions. The most favorable conditions for plants of the mesotrophic group formed in the meadow alluvial soil and in sod-forest chornozem-like soils and for semioligotrophic – in sod-forest chornozem-like gleic soil. Forest ecosystems within catena are characterized by similarity of water regime conditions. Sandy steppe ecotopes in the catena are characterized by the highest volatility of the moisture conditions. The most common acid regime within catena can be considered as characteristic for weak-acid soil / neutral soils. The acarbonatophiles are the most typical for catena studied. Plants of this ecological group are living in neutral ecotopes and kept the minor content of carbonates in the soil. The alluvial meadow marsh soil is characterized by smallest carbonates level, and the alluvial meadow solohchak soil is characterized by the largest carbonates level. In the chornozem-like pine-forest soil the effervescence from HCl treatment war not revealed. The depth of efferves-cence of processing 10% solution of HCl is 64 cm in sod-forest chornozem-like soil, 31 cm in alluvial meadow soil, 18 cm in alluvial meadow marsh soil or from the surface. The sod- forest chornozem-like soil boils on the surface. Sod-forest soil chornozem-like boils from the depth of 127 cm. The content of digestible forms of nitrogen is an important aspect of the edaphotope trophicity. Within catena the most typical is an ecotope where conditions are favorable for ni- trophiles. The lowest level of nitrogen nutrition set was found in sandy steppe (chornozem-like pine-forest soil), and the highest ‒ in the forest ecosystems (sod-forest chornozem-like soils). The subaerophiles are the most typical for catena studied. The marsh biogeocoenosis are characterized by significantly aggravated conditions of aeration. It generated conditions conducive to subaerophobes-aerophobes. Keywords: catena, arena, soil profile, nature protection, diversity, morphology