Moscow University Soil Studies Bulletin. 2023. 1.

We studied the soils and vegetation cover of tombolo – bridges between the mainland and small islands on the coasts of the White and Baltic Seas. Tombolo are characterized by complex dynamics of sedimentation that determines a high level of heterogeneity of soils and associated vegetation cover. At the Kolezhma plot on the White Sea coast, ground- and surface-gley marsh soils are formed. Vegetation corresponds to marsh meadows of the lower and middle levels, and varies depending on salinity, acidity level and soil texture. At the Gakkovo plot on the Baltic Sea coast, soils are characterized by greater uniformity; in general, they have a sandy texture. The influence of the Baltic Sea on the soil and vegetation cover is significantly lower than that of the White Sea due to the weakly pronounced tidal dynamics of the Baltic Sea.

Spatial and temporal variability of the vegetation index were investigated in the vicinity of the anthropogenic source of heavy metals. The analysis of the special points of the theoretical equation of the dependence of the concentration of photosynthetically active biomass on the resulting concentration of pollutants in the soil revealed the maximum permissible concentration of heavy metals in the soil. The results of its determination in the northern forest-steppe under the current level of anthropogenic pressure, according to MODIS materials, amounted to 12,3, according to Sentinel-2 — 12,5 mg/kg, respectively. A method for generalizing the macrokinetic patterns of the response of the living organisms to anthropogenic impact is proposed. The results of the environmental risk assessment showed that the probability of exceeding the threshold concentration is 74%.

Based on the five-level quality scale and the indicator of soil state, the quality of soils and vegetation cover was ranked. The areas of the same resistance of soils and vegetation to the action of pollutants in the plant impact zone were mapped. Territories near the plant mostly correspond to the I and II categories of soil quality. The natural protection zone of the enterprise is allocated, and background territories are defined.

For the purposes of ecological monitoring, the features of living ground cover and forest floor in spruce stands within Moscow urban territory were studied. Using ecological scales by Nitsenko, Ramensky, Ellenberg and Landolt, let to consider, that ruderalization of living overground cover is a result of recreation. Independently of spruce forest type, the absence of undergrowth results in increasing light penetrating and increasing species quantity. Variety of ecological spaces is a result of moderate trampling, which is mostly expressed in between-crown spaces. Hight trophy index by L.G. Ramensky is a result of increased weediness of overground cover. It is shown, that living overground cover characterizes the variety of tree layer and the level of anthropogenic impact on phytocenosis.

The forest floor in urban spruce stands is sensitive to changes in functioning conditions and can be used for ecological monitoring. Availability of forest floor studying and simplicity of parameter estimation allows getting information about organic matter accumulation in express-regime under various degrees of anthropogenic impact on urban ecosystems.

Within the system of trunk, crown and open space, the simplification of litter structure and decreasing organic matter total deposit are observed — this can be considered an invariant process.

Maximal uniformity of coverless spaces litter, composed by needles and branches, results from absence of living overground cover, in combination with low recreation in these spaces. This fact let to conclude, that coverless spaces are able to be used as most important objects for comparing spruce ecosystems with different overground cover. Two groups of indexes, characterizing structure-functional litter organization, are proposed. Indexes, characterizing structural litter organization, include the total deposit of litter and L horizon deposit. Indexes, characterizing functional litter features, include deposit and proportion of detritus as well as the same for easy-decomposed components, ratio of thickness (deposit) of L horizon and F horizon. The peculiarities of long-term spatial functioning are characterized by litter typology in the system trunk-crown-open space.