We propose a scheme of soil-degradation zoning of Lviv Oblast, which comprehensively illuminates the problem of degradation and focuses on regional differences in the manifestation and complexity of dominant degradation processes. The highest taxonomic unit of soil-degradation zoning is the soil-degradation country, which in turn is divided into a soil-degradation zone, province, county and district. This classification is based on the landscape features of the study area, the dominant types and kinds of degradation processes. In accordance with the zoning of Lviv Oblast, we have identified the following soil degradation taxa: 2 countries, 3 zones, 5 provinces, 14 counties and 31 districts. The soil-degradation country of the East European Plain unites two soil-degradation zones: Polissia mixed forests and broad-leaved forest zones. The soil-degradation zone (Polissia mixed forests) is best characterized by the processes of deflation and physical degradations. The processes of water erosion and physical degradation of soils dominate within the soil degradation zone (broad-leaved forest zone). Those zones also manifest pyrogenic and chemical degradations. The Carpathian soil-degradation country within Lviv Oblast (the Ukrainian Carpathian zone) is characterized by the distribution of geo-ecological anomalies, mechanical and physical soil degradations. The complex lithological features and geomorphology of the territory in the context of uneven anthropogenic impact determine the intensity of manifestation of degradation. Disturbing the natural stability of the soil cover in the conditions of the mountainous terrain contributes to the activation of the manifestation of degradation processes of geo-ecological anomalies. The problem of soil degradation in Lviv Oblast in the conditions of long-term, intense, and often consumer-orientated agricultural use is considered one of the most urgent tasks of modern agricultural production, soil science, ecology, land management, and environmental protection in general. In addition to arable land, the soils of the Carpathians are degrading due to excessive and often predatory deforestation, recreation and pressure from tourists. As evidenced by numerous scientific publications and our own research, soils are subject to water and wind erosions, overconsolidation and loss of structure, dehumification, depletion, desiccation and aridisation, pyrogenic degradation, contamination by agrochemicals, domestic and industrial wastes, etc. The status of the soils and land resources of the study area is close to critical.

This publication deals with the erosive degradation of chernozem soils in the context of the the Prydnisterska Upland relief. The structure of the soil coverage of the studied area is represented by two subzonal subtypes of chernozem soils. Precisely: typical and podzolic, with a total area of 4 060 km2 (62% of the territory). The major part of these are flat interfluve: flat interfluve, wavy interfluves dissected by beam and valley forms, high fragmentary terrace complexes with insignificant horizontal dismemberment. The background surfaces of the intensity of erosion chernozem soils degradation are slopes of different steepness, exposure and morphometry. With the help of the geoinformational program ArcGIS, the distribution of slopes with the corresponding parameters of steepness and total area is determined. Inclined slopes with the steepness of 1–3° (1 700 km2) are dominant. The area with a steepness of 5° or less is approximately 87% of the total area of chernozem soils. However are of slightly inclined relief with only mere erosion occurant. The steep surfaces expositional distribution indicates the predominance of the southern, southwestern exposure slopes of an average length of 500–1 500 m. The results of the field morphological studies show that in the 5–6° – incline surfaces of inflection areas chernozem podzolic and strongly washed away. The degree of typical chernozem soils erosion is mostly associated with transversely convex and slightly convex slopes. In accordance with the degree of erosion, slightly washed typical chernozem soils formed on the same slopes of 2–3°, medium washed on 3–5°, strongly washed 8° incline. However, on the oblique slopes with an incline of 3–5° of complex shapes, typical chernozem soils the entire humus line is washed away. Particularly critical degree of chernozem soils erosion is observed within the complex slopes of river meanders and beam girder systems. In addition to the listed morphometric parameters of slope surfaces, the development of erosion degradation is influenced by the local unreasonable placement of linear boundaries. Thus, roads laid perpendicularly to river valleys and watersheds or along the plane of individual slopes form artificial bases of erosion, accelerating degradation processes. The formation of natural quarries leads to the active development of linear erosion of regressive nature. Key words: podzolic chernozem; typical chernozem; Prydnisterska Upland; GIS-analysis; erosive degradation; slope morphology; relief.

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