CLIMATE-DRIVEN CHANGES OF KURUM LANDSCAPES IN THE WEST OF THE CENTRAL SIBERIAN PLATEAU WITHIN THE MIDDLE TAIGA ZONE

The change of bioproduction indicators on the kurum slopes of the western part of the Central Siberian Plateau under the modern climate warming is considered. The change in heat availability over the period from 1991 to 2020 was estimated in comparison to 1961-1990, and an increase in the sum of active air temperatures above 5°C and 10°C was noted by an average of 165°C and 8 days for both cases. The kurum slopes in the study areas were identified based on the processing of remote sensing data (satellite images of the Landsat series with 30-meter resolution and the Sentinel-2 with 10-meter resolution). The vegetation index series (NDVI and NDMI) were calculated for them using the archives of these images. This made it possible to assess the dynamics of photosynthetically active phytomass and moistening of the ground cover from 1992 to 2023. The index values were calculated as the maximum for the growing season (July-August) of the analyzed year for all low-cloud Landsat and Sentinel-2 scenes available for observation. In general, the interannual change in the NDVI and NDMI values averaged over the analyzed kurums tends to increase. There is a positive dynamic in the fluctuations of both vegetation indices during the study period. The kurum landscapes were typified by the rate of their overgrowth, kurums with the largest, average and smallest difference of the obtained values were identified, and their spatial distribution was estimated. The role of morphometric characteristics of slopes (including their exposure) in the processes of kurum overgrowth was analyzed. It was revealed that the maximum values of the growth of vegetation indices correspond to the slopes of cold exposures (northern, north-western and eastern), while the influence of steepness is insignificant. The positive dynamics of the values of vegetation indices allows suggesting the “greening” of kurum landscapes, which is also confirmed by the results of repeated studies at the key sites. The overgrowth of kurums includes the increase in the area and height of moss-lichen cover, the appearance of shrubs, the active growth of young small-leaved trees and rare undergrowth of conifers. The “greening” of kurum slopes is accompanied by the melting of the char ice, therefore, the middle taiga kurums of the Central Siberian Plateau become more characteristic of the southern taiga, which indicates a change in zonal landscape conditions in the areas of their occurrence.