REGULARITIES OF THE MICROELEMENT COMPOSITION FORMATION OF SOILS UNDER THE MOUNTAIN-MEADOW VEGETATION OF THE GREATER CAUCASUS

Report. The purpose of the work is to identify the features of the formation of the microelement composition of soils under the mountain meadow vegetation of the Greater Caucasus based on the analysis of literary materials and the results of our own field research. Methods. The study of the microelement composition of soils under subalpine and alpine vegetation was carried out on the territory of the Teberdinsky State Biosphere Reserve. Traditional methods of soil-geochemical studies were used with the laying of soil sections, the selection of soil samples and their analysis for the content of four trace elements (Zn, Cu, Pb and Cd). Determination of trace elements was carried out by voltammetric and atomic absorption methods. The humus content was determined by the Tyurin method with wet salting, the pH of the water extract was determined potentiometrically. Statistical processing of the obtained data was performed in the Statistica 10 program. The microelement composition of soil-forming rocks was compared with the clarks of chemical elements in the upper part of the continental crust; the microelement composition of mountain-meadow soils was compared with the clarks of the soils of the world. The radial distribution of trace elements in the soil profile was analyzed. The qualitative trace element composition of soils was characterized as a sequence of decreasing the content of trace elements in the humus horizon. Results. It is established that the microelement composition of soils under the mountain-meadow vegetation of the Western Caucasus is formed under specific conditions that affect the course of soil processes. High solar insolation, low temperatures, intensive humidification throughout the year affects the features of the processes of humification, the formation of clay minerals in the soil and other products of intra-soil weathering. The predominance of acid hydrolysis processes leads to the predominant accumulation of aluminosilicates, Fe hydroxides, chelated organomineral complexes in the soil profile, which play a leading role in the binding of trace elements. The microelement composition of mountain-meadow soils under subalpine vegetation is formed with more intensive processes of humus formation and oglinivaniya. These soils are characterized by a more pronounced biogenic accumulation of Cu and Zn in the humus horizon, the illuvial nature of the Cd distribution is more pronounced. The microelement composicomposition of mountain-meadow soils under alpine and rock-scree vegetation is formed against the background of relatively weakened processes of humus formation, humus accumulation and oglinivaniya. This affects the lower intensity of biogenic accumulation of trace elements, their leaching into the lower part of the profile. Conclusions. The main regularities of the formation of the microelement composition of mountain-meadow soils are determined by the special conditions in which these soils develop. The fixation of trace elements in mountain-meadow soils occurs mainly on aluminosilicates, Fe, Mn hydroxides and chelated organomineral complexes, which largely form the silty fraction. The movement of silty particles along the soil profile leads to the redistribution of trace elements associated with them. The granulometric composition, which is an indicator of the content of the silty fraction and its distribution along the soil profile, is of great importance when characterizing the microelement composition of mountain meadow soils. The established regularities of the formation of the microelement composition of mountain-meadow soils allow us to determine the main directions of economic activity that will contribute to the preservation of their ecological state. This is, first of all, the rational use of pasture resources of mountain meadows with the introduction of a system of alternating mowing, changing the main pastures with spare ones during the year for their restoration. An important component should be monitoring changes in the trace element composition of mountain meadow soils, which will allow timely response to changes and make adjustments to the structure of the use of these soils.

Study of mountain-forest, mountain-meadow and mountain-shrub landscapes of the low and moderately mountainous of the Lesser Caucasus by satellite imagery

The article analyzes mountain-forest, mountain-meadow and mountain-shrub landscapes of the low and moderately mountainous of the Lesser Caucasus by satellite imagery. The development, anthropogenesis of mountain-forest, mountain-meadow landscapes with space materials are characterized in detail Key words: landscape, satellite images, interpretation, indigation, transformation, differentiation

CHANGES IN THE CONTENT OF BIOAVAILABLE HEAVY METAL COMPOUNDS IN THE SOILS OF THE CRIMEAN MOUNTAIN PLATEAUS AFTER AFFORESTATION

About 3 thousand hectares of forest stands were created on the surface of the Crimean mountain plateaus in the middle of the 20th century as a result of afforestation. Studies on the influence of these stands on the properties of mountain meadow soils (Phaeozems) showed that under the forest vegetation, the consolidation of structural aggregates, a decrease in the humus content, and an increase in acidity compared to the soils under the meadow vegetation, which could also affect other soil properties, including the mobility of some metals, were observed. The work objective of this research is to conduct a comparative analysis of the content of Pb, Mn, Cu, and Zn compounds available for biota (1 M ammonium acetate) in the soil under mountain meadows, natural beech forest, and artificial forest stands. Following the obtained results, the available Pb, Mn, and Cu compounds accumulated in the afforested mountain meadow soils relative to the adjacent mountain meadows areas. Thus, the average Pb content in the soil layer of 0–10 cm under the mountain pine stands in comparison with the soil under meadow vegetation was 1.6 times higher, Mn – 1.2 times, Cu – 1.2 times. The Pb content was 2.5 times higher, Mn – 1.5 times higher, and Cu – 1.2 times higher under the silver birch stands. The Pb content was 2.2 times higher, Mn – 2.4 times higher, and Cu – 1.5 times higher under Siberian larch stands. The Pb content was 1.9 times higher, Mn – 1.1 times higher, Cu – 1.3 times higher under the sycamore maple stands, compared to the meadow. Differences between afforested and meadow soils in the content of these elements in most cases were significant, except for the Zn content, signs of accumulation of which under artificial stands were not revealed. The Pb, Mn, and Cu content in the brown forest lessive soil (Luvisols) under the oriental beech corresponded to their concentration under the larch, and the Zn content was significantly higher compared to the soil under all species. The main reason for the increase in the mobility of some elements under tree stands is their transition from immobile forms under the influence of increased acidity of afforested soils. Wood litter due to the low content of trace elements in its composition cannot be a source of their accumulation in the topsoil.

Biological activity of mountain meadow subalpine soils of Central Caucasus

Indicators of biological activity (humic content and stock, Cmic content and stock, hydrolytic and redox enzymes activity) were measured for the first time in the upper horizons of mountain meadow subalpine soils of Central Caucasus (elbrus altitudinal zonality in Kabardino-Balkaria). The comparative assessment was performed for the biological characteristics together with soil density and acid-base properties for soils of natural and pasture ecosystems. The integral index of ecological and biological soil state (IIEBSS) was calculated to estimate the level of changes in biological activity. It was shown that pasture degradation leads to 30% decrease of IIEBSS compared to the undisturbed soil. The defined biological parameters of natural undisturbed mountain meadow soils could be used as diagnostic indicators for the ecological studies of ecosystems under anthropogenic load.

The current state of mountain meadow soils of subalpine pasture ecosystems of the Central Caucasus (elbrus altitudinal zonality)

Intensive recreational, agricultural and logistics land use in uplands leads to their transformation and degradation. Subalpine meadow ecosystems of Central Caucasus are traditionally used for grazing and mowing. The work determined the current state of soils on pastures (mountain meadow-steppe subalpine soil and mountain meadow subalpine soil) and the level of changes of their properties under different stages of pasture degradation were defined. The efficacy of 4-stage assessment system for evaluating the pasture degradation of grasslands dominated by Bromus variegatus M. Bieb. was shown for the assessment of soil cover condition. The reduce of estimated soil indicators and degradation of soils under pastures with maximal degradation stage (DS3) of meadow ecosystems was statistically significant.