Soil-degradation zoning of Lviv oblast

W.P. 3 Rohatyn-Opilia soil-degradation county within Lviv Oblast occupies a small territory in its southeast part, including Hodoriv soil-degradation district. The commonest degradation processes are water erosion with dominance of water-erosion degradation, overconsolidation of soils, de-structuring.

WP. 3.1 Hodoriv soil-degradation district of water- erosion and physical degradation of soils, shifts. Soil cover is formed by podzolized and typical chernozems, dark greay podzolized soils. In the area, common degradation processes are water erosion, excessive compaction of soils, de-structuring, and dehumification. The district has long history of agriculture, the soils are being intensely used for tillage, namely for growing sugar beet, leading to overconsolidation and loss of soil structure, and agrotechnical exhaustion of soils is observed. On the slopes of ravines, river valleys, shifts occur. Flat interfluves and slopes of ravines have overmoistened boggy soils (bog-type degradation).

Carpathian soil-degradation country (C) (zone of the Ukrainian Carpathians). Within Lviv Oblast, it occupies its southern part, including soil-degradation provinces of the Eastern Carpathian Foothills and the mountaneous part of the Carpathians. The territory is characterized by complex lithology, geomor- phological peculiarities and soil cover. In the structure of soil cover, there dominate sod-podzolized and podzolized-turfy surface-gleyed, turfy, alkaline, wetland, brown earth-podzolized soils and brown earth (Andrushchenko, 1970).

Cultivation of this territory varies and is not homogenous across the regions, which is reflected in the development of degradation processes. The commonest degradations in the area are geoecologically anom-alous, mechanical and physical degradations.

EC - the Eastern Carpathian Foothills' soil-erosion province of mechanical and physical degradations. It is a specific soil-degradation province, located between the southwest margin of the Podilia upland and northeast margin of the Ukrainian Carpathians. The upland of the Eastern Ukrainian Foothills is character-ized by significant segmentation with great height amplitudes. The territory is composed of deluvial, Ancient alluvial and contemporary alluvial deposits (Palienko et al., 2012).

In the soil cover, there dominate sod-podzolized and podzolized-sod surficial gleyed, sod, alkaline, brown earth-podzolized, wetland soils and peatlands. Degradation processes are related to water erosion, physical degradation, geoecological anomalies, and technogenic disturbances. Within the province, there were distinguished two soil-degradation counties: the Podnistersky terrace and Drohobych-Morshyn.

EC.1 Podnistersky terrace soil-degradation county of physical, pyrogenic degradations, it occupies low gypsometric levels with the absolute heights of 260275 m and is geomorphologically confined to the Upper Dnister (Upper Dnister-Stry) alluvium terrace plain. It is a flat, undulating in places and slightly segmented alluvium plain, confined to the floodplain, the first and the second terraces of the Dniester River and its right tributaries. Soil cover is quite homogenous; its basis comprises alkaline and alluvium-alkaline, alkaline- wetland and wetland, depression peatlands, sod soils. The cultivated land accounts for around 45 % of the territory, and at the same time large areas are occupied by hayfields and pastures, indicating moderate pressure on soils and soil cover. Degradation processes in soils are associated with physical, chemical, biochemical and pyrogenic degradations. Within the county, there are distinguished two soil-degradation districts: Sambir and Stryi-Zhydachiv.

EC.1.1 Sambir soil-degration district with dominance of physical and pyrogenic degradations of soils, occupies the western part of the Podnistersky terrace county and geomorphologically correlates with the Upper Dniester structural basin. It is a flat plain, within the floodplain and the first above-floodplain terrace, significantly waterlogged, becoming completely filled with water in wet years. The popular name is Velyke Boloto [Ukr.- Great Bog] and it is used for pastures and hayfields. Plots of the second above-floodplain terrace are being tilled, occupy a relatively small area, pressure on soils may be assessed as low. Soil cover is represented by alkaline, sod soils and depression peatlands. Degradation processes in the tilled lands are mostly related to physical degradation through overconsolidation, de-structuring, block formation, frac-turing. Mechanical degradation is conditioned by siltification of surfaces of mineral and organogenic soils. In soils, processes of dehumification, acidification and decalcination take place. In peatland soils, pyrogenic and hydrothermal degradation occur.

EC.1.2 Stryi-Zhydachiv soil-degradation district with dominance of physical degradation and techno-genic disturbance. It occupies the eastern part of the county and is confined to the valley of the Dniester and its right tributaries Tysmenytsia, Kolodnytsia, Stryi and Svicha. Most of this territory is known as the Stryi- Zhydachiv hollow, which is a floodplain and the first- second terraces of the Dniester and Stryi. The terrotory is represented by a flat alluvial plain, which has been significantly waterlogged in the past. The share of cultivated land in the structure of land fund is relatively small. Soil cover is represented by alkaline and alluvial alkaline soils, sod and sod-podzolized, and small spots of alkaline-chernozem and wetland soils. Peatlands are rare. The most common degradation processes are physical degradation (excessive compacton, de-structuring, fracturing), as well as dehumification, acidification of soils. There are large structures of technogenically disturbed soils due to open extraction of peat.

EC.2 Drohobych-Morshyn soil-degradation county of mechanical, physical and geoecologically anom-alous degradation. As a stretch with varying width, it strikes from the northwest to southeast, along the Beskid. It is a pre-mountain, staircase-like segmented denudation-accumulative upland. In the structure of soil cover, sod-podzolized and podzolized-sod, surface- gleyey and brown earth-podzolized gleyed soils dom-inate. Small spots of sod-podzolized gleyey, sod gley- ey and grey forest gleyed soils occur. Exploitation of soils, particularly for tillage, is more intese in this area than in the previousl described soil-degradation county. Processes of mechanical, physical, biochemical, chemical, geoecologically anomalous and technogenic degradations have developed. Within the county, two soil-degradation districts are distinguished: Drohobych and Morshyn.

EC.2.1 Drohobych soil-degradation district of distribution of water-erosion, physical degradation, geo-ecologically anomalous degradations and technogenic disturbances of soils. Geomorphologically, it corre-sponds to the Drohobych denudation-erosion upland and partly Stryvihorsky (Stryi Mountains) denudation- accumulative upland. Absolute heights reach on average 300-400 m. The terrain of Drohobych upland com-bines wide waterlogged valleys with deeply cut currents with the hollow-wavy areas between rivers, confined to the fourth, fifth and sixth above-floodplain terraces of the Dniester. The areas between the rivers are cut by a network of ramified gullies. Significant segmentation contributes to the development of erosive processes. Soil cover is characterized by sod-podzolized and podzolized-sod surface-glayed and brown earth- podzolized gleyed soils with insignificant share of sod and grey forest soils. This part of the Eastern Carpathian Foothills is a territory of Ancient agriculture and livestock farming. Cultivated land accounts for around 45 % of the district's area. A broad range of degradation processes has developed in the area, first of all mechanical degradation related to water erosion, pasture- caused and agrotechnological erosions, and also silt- ification. Physical degradation manifests in overconsolidation, de-structuring, block formation, fractur-ing. There also is a secondary waterlogging within the depressions of the terrain, caused by peculiarities of lithology. Dehumification-caused processes of biochemical degradation are also common. In Drohobych soil-degradation district, there are geoecological anomalies, karst, and shifts. Processes of technogenic zon-ing of soils are common due to extraction of potassium salts. Contamination of soils is caused by oil extraction and presence of tailing dams of chemical production facilities. Within and in the outskirts of Truskavets, recreation-touristic degradation of soils and soil cover is seen.

EC.2.2 Morshyn soil-degradation district of mechanical, physical and technogenic degradation of soils and soil cover. The territory is confined to Morshyn and Above-Svicha denudation-accumulation uplands downstream of the Stryi and Svicha. Absolute altitude ranges within 300-350 m. As narrow stripes, the chain of heights stretches northeast, confined to Ancient fifth above-floodplain terrace of the Dniester, mostly with flat segmented surfaces and slopes varying in steepness. Closer to the margin of the mountains, there are fragments of denudation-accumulative and denudation surfaces of the sixth terrace, which is more intensely segmented. In soil cover, there dominate sod-podzolized and podzolized-gleyed, and spots of sod soils occur. The territory is agriculturally cultivated, around 50 % of the area being tilled. Presure on soils and soil cover is significant. Degradation processes are related to water erosion, siltification of soils, their overconsolidation, de-structuring, block formation, crust formation, flooding, etc. Shifts also occur. Technogenic destruction of soil has been caused by sulfur extraction (Podorozhnianske deposits).

C--Carpathian mountaneous soil-degradation province. It occupies the southwest part of Lviv Oblast and corresponds to the mountaneous country of the Carpathians. Two soil-degradation counties are distin-guished: Beskyd and Verkhovyna. Soil cover is represented by brown earth mountaneous-forest type.

C. 1 Beskyd soil-degradation county of geoecologically abnormal and mechanical degradations. Geomorphologically it corresponds to the region of Skybovi (Outter) Carpathians. The territory of the soil degradation county is occupied by two districts: Staryi Sambir and Turka-Skole.

C.1.1 Staryi Sambir soil-degradation district of distribution of water erosion, screes, shifts, occupies the northeast part of Beskyd, partly coinciding with the borders of geomorphological district of the Upper Dniester Beskyd. The territory is characterized by of low mountainous terrain, with comparatively soft countours. Absolute heights range within 600-800 m. Soil cover is represented by brown earth of mountaneous- forest, brown earth-podzolized, sod and alkaline gleyed soils. Agricultural cultivation of the territory is at a low level, the lands are mostly used for pastures and hay- fields. Cultivation is distributed in small structures in valleys of wide rivers, steep and gently sloping slopes of water divides. Among degradation processes, there occurs mechanical degradation (water and pasture erosion, reclamation, siltification, abrasion of river banks), physical degradation (overconsolidation, de-structuring, block formation). Geoecologically anomalous processes are broadly distributed - shifts, windthrows. Touristic- recreation degradation of soils and soil cover is becoming common.

C.1.2 Turka-Skole soil-degradation district of distribution of geoeconomically anomalous phenomena occupies the south and southwest part of Beskids, its borders coinside with geomorphological district Skole Beskids (Marynych et al., 2003). In soil cover, brown earth mountaneous-forest, turfy-brown earth soils, and small areas are occupied by alkaline-brown earth soils dominate. Most areas of the land fund are forests, whereas agricultural lands occupy relatively small areas. Degradation processes are related to geoecological anomalies, specifically windthrows, screes, more rarely - shifts, sometimes with avalanches. Erosion degradation is caused by linear and area erosion in tilled areas, abrasion of river banks. Touristic-recreation degradation of soils and soil cover is also common (Saliepova, 1959).

C.1.3 Stryi-Sian soil-degradation district of distribution of geoecologically anomalous and mechanical degradation processes. It is located in the basin of the upstream Stryi and Sian. It is characterized by combi-nation of low mountaneous and low mountain-hollow areas with terrace-valleys. Geomorphologically it corresponds to Stryi-Sian Verhovyna. It is an old and densely populated, well cultivated territory. The tilled area accounts for 36.9 %, pastures and hayfields - 24.5 % and forests - around 30 %. The area of agricultural lands is too large for a mountaneous territory, and the anthropogenic pressure on soils and soil cover is evaluated as high. Soil cover of the territory comprises brown earth mountaneous-forest, sod-brown earth podzolized and gleyed soils, and spots of brown earth-podzolized gleyey soils occur. Degradation processes have been caused by the distribution of mechanialc degradation, particularly planar and linear erosions. Physical degradation has led to excessive compaction of cultivated soils. Among geoecological anomalies, shifts are common, and also screes occur at some places. Recently, tourism and recreation have been developing, leading to touristic-recreation degradation of soils and soil cover.

C. 2 Verkhovyna soil-degradation county with dominance of geoecologically anomalous and mechanical degradations of soils, occupies the southern part of Lviv Oblast. Due to structural-lithological peculiarities, low-mountaineous relief has developed in this territory, with dominance of Ancient long valleys, which has received name “Upper Verhovynsky”. Absolute heights range 450-500 to 800 m. Within the soil-degradation county, three districts were distinguished: Stryi-Sian and Volodil-Verhovyna.

C.2.1 Vododil-Verhovynsky soil-degradation district is in the marginal southwest, the highest part of Lviv Oblast. Absolute heights in the area reach 1,408.3 m (Pikui Mountain). Relative elevation above Sian-Stryi Verhovyna reaches 700-900 m. Slopes of the crest are steep, there are often rocky outcrops, accumulations of blocks, stone placers. Soil cover is represented by brown earth montane-forest and sod-brown earth soils, mostly pebbley and stony. Soils are taken over by forest vegetation, montane pastures and hayfields. Among the degradation processes, there are screes, and avalanches occur (Voitkiv and Pozniak, 2009).

All across Lviv Oblast, there occurs such a type of geoeconomical anomaly as neotectonic elevations that lead to change in the basis of erosion, and therefore to activation of erosive degradation of soils and soil cover. In tilled areas, common degradations are related to agricultural exhaustion of soils due to failure to adhere to the norms and doses of introduction of organic and mineral fertilizers. Such phenomena are present in the distinguished soil-degradation districts.

In general, the performed soil-degradation zoning shall contribute to the development of measures to minimize degradation processes, increasing productivity of agricultural lands, protection of agricultural lands, and protection of soils in general.

Conclusions

Soil-degradation zoning of Lviv Oblast has been carried out for the first time. We distinguished 2 soil- degradation countries, 3 soil-degradation zones, 5 soil- degradation provinces, 14 soil-degradation counties and 31 soil-degradation districts. Soil-degradation zoning is considered to be distinguishing certain territories united by the same factors of soil formation, similar soil cover, anthropogenic pressure and its duration, which have caused the development of single-type degradation processes or combination of several types of degradation. Grouping degradation processes into types and kinds was conducted according to the typologies developed in Ukraine.

Common degradations in soils of Lviv Oblast are water and wind erosions, excessive compaction and loss of structure, dehumification, dessication and ari- disation, pyrogenic degradation, contamination by ag-rochemicals, domestic and industrial wastes, acidification, etc. The status of the soils and land resources of the territory of the study is close to critical.

Soil-degradation zoning of the territory shall help in optimizing the use of soils by providing protective measures, concervation of severely degraded lands, allow the fertility of degraded lands to be increased, and most importantly prevent the further activation of degrading processes and protect soils,- our priceless treasure. The soil-degradation zoning we proposed has important methodologic significance. We recommend that this procedure be carried out for other regions, as well as the territory of Ukraine in general.

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