Structural changes of the three-segment desert and steppe complex in Saratov Priuzenie area (based on Earth remote sensing data and ground-based observations)

Abstract

Northern semi-desert with zapadinny microrelief area is located in the south of Saratov Oblast. Microrelief contributes to moisture redistribution and its accumulation in micro-depressions (swales, or Russian name “zapadines”) under conditions of extremely low precipitation (312 mm per year). This allows to form a specific surface, where micro-slopes with light chestnut soils (44.1%), micro-hills with solonetzs (37.5%) and micro-depressions with meadow chestnut soils (18.4%) coexist. Studies of the microcomplex semi-desert were carried out in Aleksandrovo-Gaysky district at the key site (100 × 100 m) in 2010 and 2020. The morphological structure of the landscape is preserved, but the quality of soil and vegetation cover has changed significantly. The projective cover of the herbaceous layer has decreased by 20-30%, the species diversity has significantly decreased as well. Herbaceous vegetation has almost disappeared in the micro-depressions, and the height of the spirea shrub has decreased from 1-1.4 m (2010) to 0.5-0.7 m (2020). Semi-desert landscapes are used for grazing cattle, sheep, goats and horses. The density of pasture trails on the key site was 0.11 m/square m in 2010, and 0.17 m/square m in 2020. The landscape area disturbed by livestock trails increased from 3% (2010) to 4.7% (2020) of the site area. The upper soil layer on trails is in a loose state to a depth of 4-6 cm. It is necessary to reduce pasture load, limit grazing time and take measures to organize the Priuzen semi-desert reserve to preserve microcomplex semi-desert landscapes.