The influence of debris-flow processes on the transformation of soil and vegetation cover of the Central Caucasus

Abstract

Relevance. Debris-flow processes in the Central Caucasus rapidly transform mountain landscapes by disturbing the soil profile, vegetation cover, microrelief, and surface runoff conditions. Vegetation may recover faster than soil, which complicates the assessment of disturbed areas. Aim. The study aims to assess changes in soil and vegetation cover under the influence of debris flows, with division of the territory into erosion, transit, and accumulation zones. Methods. Field descriptions of debris-flow sites, soil profiles, layer- by-layer sampling, geobotanical observations, UAV materials, and remote sensing data were used. The analysis included deposit thickness, preservation of the humus horizon, granulometric composition, stoniness, share of exposed mineral substrate, vegetation cover, species composition, NDVI values, and site position relative to the debris-flow channel. Results. It was established that erosion zones are dominated by washout, removal ofthe humus horizon by 15–80 cm, and a sharp decrease in vegetation cover from 70–90% to 5–18%. In transit zones, gullies, deposits, and turf fragments alternate, whereas in accumulation zones the former surface isburied under deposits up to 1.2–1.5 m thick. Vegetation partially recovers within 1–8 years, while the soil profileretains disturbance features for 20–50 years or longer. The results are applicable to geoecological monitoring and debris-flow hazard mapping.