Features of Spatial Distribution of Thicknesses of Organic and Humus Horizons of Soils in Forested Landscapes of Dry-Steppe Zone

The paper considers the features of the spatial distribution of litter layers and humus horizons of soils in a forested area. The study object is represented by forest-cultural landscapes on low-productive sandy lands created in the early 20th century to protect against deflation. The territory is located in Kamyshin raion of Volgograd oblast (cadastral quarter 34: 36:000014). The purpose of the research is to determine the distribution of the thickness of organic layers and humus horizons in relation to the composition of plantations (coniferous or deciduous species) and to the total projective cover and dominant associations of the herbage. The performed research is relevant and aimed at evaluating the effectiveness of forest reclamation measures on sandy lands in the dry-steppe zone. Both terrain (soil and geobotanical) and remote (agroforestry mapping) research methods have been used. The analysis of vegetation and ground cover has shown that, despite their age, forest plantations do not favor the formation of litter and humus horizons on the surface of sandy soils. However, deflation processes are damped in most of the area: sands are fixed by massive plantations and by the formed grass cover. The relationship of the stand composition and the general projective cover with the dominant herbaceous association and the thickness of humus and litter horizons in coniferous plantations is established. The number of the studied layers increases in mixed forests with coniferous and deciduous trees under the effect of their debris. The spatial heterogeneity of the analyzed parameters on all the studied plots is primarily influenced by the low decomposition rate of the debris, as well as by the internal redeposition of organic and humus horizons under the wind effect.