Spatial-time dynamics of the upper forest boundary on the Kyabyak ridge in high-mountain Dagestan (by remote sensing)
Purpose. The paper presents the results of a study of the influence of modern climate changes in High-Mountain Dagestan (on the example of the weather station «Akhty») on the position of the upper border of the forest according to satellite surveys for 1987-2019. Methods. The analysis of climatic conditions for 1928-2018 was carried out using statistical methods. To detect changes in the position of the upper forest boundary, we used visual and composite decoding of multi-time medium-resolution satellite images from Landsat satellites, the vegetation index NDVI was also used. The analysis of topographical conditions of the area was carried out on the basis of a digital terrain model and GIS technologies. Results. Analysis of climatic conditions revealed that they changed according to the scenario of increasing air temperature and, especially in recent decades, the amount of precipitation. The result was a change in the position of the upper boundary of the forest, which, along with climatic conditions, is associated with local topographical conditions such as absolute height, steepness and exposure of slopes. Summaries. According to the data of the Akhty weather station for 1927-2018, the average annual temperature increased from 8.5 to 9.5°C, precipitation increased from 340 to 390 mm, while the Selyaninov hydrothermal coefficient changed from 0.64 to 0.68, and climate changes were most pronounced in the last few decades. The result was an improvement in the conditions for the growth of forest vegetation, and its upper border on the Kyabyak ridge in High-Mountain Dagestan increased by an average of 80 m in 1987-2019.The result of the study was a thematic map on a scale of 1:200 000, reflecting the spatial and temporal dynamics of the upper forest boundary of the studied territory.