Chemical and ecological properties of soils and the NDVI analysis on reclaimed sulfide coal waste dumps in the boreal zone

Reclamation of coal waste dumps through the establishment of a stable soil and vegetation cover on their surface contributes to the restoration of ecological systems. Therefore, studying the properties of soils in technogenic landscapes is of current importance. The problem of biological reclamation was studied in the Kizel Coal Basin area. The effectiveness of reclamation was evaluated on several sulfide coal waste dumps. The reclamation methods, as well as the period of soil-vegetation cover formation, varied. Agrochemical properties of the dump soils were studied using unified methods. The NDVI (Normalized Difference Vegetation Index) was calculated based on Sentinel-2 and Landsat 7,8 images. To assess biological activity, phytotesting was used. The lithostrats ranged from slightly acidic to neutral (pH-H2O = 6.1-6.8); the embryonic soil showed a slightly alkaline reaction (7.9). The embryonic soil, due to the presence of coal particles, had the highest organic matter content (12-7.7%). Depending on the "age" of the soil, the amount of organic matter in the lithostrats varied: for the 7-year-old lithostrat, it ranged from 2.4 to 8.9%, while for the 4-year-old lithostrat, it was less than 1%. The absorption capacity of the lithostrats was similar to that of the background soil. The dump soils were characterized by low levels of nutrients (NPK), with the 4-year-old lithostrat having the lowest N content. The dump soils demonstrated favorable conditions for plant growth, as evidenced by the height and biomass of cress and oats. The calculated NDVI for all dumps ranged from 0.4 to 0.6, indicating the presence of a stable vegetation cover. The implemented reclamation measures proved to be effective.