Dynamics of Changes in NDVI, Black Carbon, and Soil Moisture at the Burtinskaya Steppe Site of the Orenburg Nature Reserve According to Satellite and Ground Data in 2000–2022

Abstract—In this work, the dynamics of changes and trends in climatic conditions, Normalized Difference Vegetation Index (NDVI), humidity of the upper soil layer, and content of black carbon in the atmosphere in conditions of steppe fires according to ground and satellite measurements for the period of 2000–2022 is traced for the Burtinskaya Steppe site of the Orenburg Nature Reserve. The negative trend in values of the Selyaninov hydrothermal coefficient (HTC) indicates a tendency to weaken the moisture supply of the territory, which favors the appearance of steppe fires. The consequence of climatic trends is a positive trend in values of black carbon in the atmosphere of the studied area, as well as a tendency to a decrease in humidity of the upper soil layer. Absolute interannual values are distinctive for 2010: the minimum value of NDVI and soil moisture, and the maximum value of black carbon.