Features of the biogeocycle and carbon dynamics in the landscape ecotone "mountains – plains" (using the example of the carbon polygon of the Chechen Republic, Russia)

The objective was to develop a biogeocycle scheme based on the study of the seasonal dynamics of mountain-forest ecosystems in the "mountains – plains" landscape ecotone. The work is based on semi-stationary observations at three sites of the Carbon Polygon of the Chechen Republic. In different seasons of the year the course of temperature, humidity and precipitation was recorded and landscape-phenological and landscape-geophysical surveys were carried out, including the description and measurements of the set and combination of the main geomasses and geohorizons that make up vertical structures and sampling to determine phyto- and mortmasses. Eight types of daily hydrothermal states of natural complexes are identified, which, in combination with trends in the biogeocycle, create 15 landscape-ecological states characterised by different conditions of the biogeocycle and carbon dynamics. In the lowlands, a relatively simple biogeocycle is observed; a certain part of the phytomass is deposited in the trunks, branches and roots of trees. In the foothills, the biogeocycle shows multidirectional trends in carbon dynamics. Preferential loss of carbon due to rapid mineralisation of mortmass with partial accumulation of carbon in the soil is observed in broad-leaved foothill-plain forests. Seasonal dynamics of phyto- and mortmass in key areas differ. Three possible ways of influencing the biogeocycle in order to increase the positive carbon balance are substantiated.