Samarska M. Restoration and creation of shelterbelts using juglans regia based on the principles of regenerative land use in the steppe zone of Ukraine

The dissertation is devoted to the study of the possibility of applying regenerative technologies for the restoration and creation of shelterbelts using Juglans regia in the Steppe zone of Ukraine. The current condition and structure of linear protective plantations along the Dnipro-Zaporizhzhia highway, which include Juglans regia, were analyzed. Twelve sample plots with a total length of 3000 m were established. The species composition, structure, sanitary condition, average diameter, and protective height were determined. It was found that most shelterbelts consist of only one row of trees, within which gaps often occur, increasing the distance between trees (8–10 m or 5 more). On all plots, mass natural regeneration of Fraxinus pennsylvanica and Ulmus pumila was observed. Juglans regia regeneration was also identified, represented by isolated individuals of various ages in good condition. The sanitary condition of the stands was analyzed, showing that the Vitality Index (VI) ranged from 1.7 to 2.3, classifying the stands as “weakened.” The best condition was observed in Acer platanoides and Tilia cordata, while the worst – in Catalpa bignonioides, Prunus avium, and Ulmus pumila. A phytosanitary analysis of Juglans regia revealed frequent dieback of skeletal branches and shoots, and 4.2% of trees had mechanical damage. It was found that shelterbelts with sparse planting (8–9 m spacing) had lower protective height but better tree health, especially for Juglans regia. To promote sustainable development of shelterbelts along highways, the use of regenerative soil biotechnology was investigated. The soil mycobiome of shelterbelts near roads was studied and found to include 35 species from the Zygomycota and Ascomycota phyla. The mycobiome of a Juglans regia nursery was also examined, comprising 41 species. Significant differences in species composition and dominance were observed between the two ecotopes, reflecting soil degradation levels. The effect of the biopreparation “Mykovital” (with endophyte Vitasergia svidasoma PRJNA807518 Oliferchuk) on the metagenome of the nursery soil, characterized by excess organic matter and high pathogen levels, was studied. The preparation showed a strong positive regulatory effect on the walnut mycorrhizosphere, with reduced pathogen and toxin-producing populations and increased diversity and abundance of mycorrhizal fungi. Treated soils showed an increased proportion of Ascomycota, which perform key functions in terrestrial ecosystems. For the first time, the application of regenerative land-use biotechnology has been recommended, involving the treatment of walnut seedling root systems before planting with a mixture of mycorrhiza-promoting preparations to establish and 6 restore the mycorrhizal network in shelterbelt ecosystems, thus improving their resilience. Based on the findings, Juglans regia can be recommended for use in roadside shelterbelts, with spacing between trees increased to at least 6 m and planting rows located further from the road. Guidelines have been developed for reconstructing protective shelterbelts by introducing resilient tree and shrub species into existing roadside plantings.