Assessment of the Influence of the Earth's Surface Temperature on NDVI by the Example of the Yangan-Tau Geopark

Abstract

The purpose is to determine the types of vegetation most dependent on changes in the temperature regime at the Yangan-Tau Geopark (Nasibash site) of the Eurasian carbon polygon (Republic of Bashkortostan). Materials and methods. The dynamics of the NDVI indicator from May to September from 1982 to 2022 was analyzed using 110 Landsat images with the association in groups of 5 years. The average value, mode and median of the NDVI indicator for each five-year period are determined. Images of the Landsat 8-9 program were used for remote assessment of the temperature regime. In the SAGA GIS program, the relationship between the Earth's surface temperature and NDVI for each snowless month was evaluated using averaged images of the Earth's surface temperature and NDVI. The maps of the spatial distribution of the determination (r2) coefficient are constructed. Results and discussion. The month of June is characterized by an increase in the NDVI value. The months of May, July and August do not show significant changes, but the average and median values for the month of September tend to decrease. The greatest relationship between NDVI and the temperature of the Earth's surface is shown by fallow lands overgrown with pine (stage 4 of overgrowth), not overgrown fallow lands and haymaking. Conclusions. Vegetative activity of vegetation on the site of the carbon polygon «Yangan-Tau Geopark» has increased since 1982 in June, due to the influence of temperature in May. The areas in the 1st and 3rd stages of pine overgrowth have demonstrated the greatest resistance to changes in the temperature regime.