Estimation of the above-ground phytomass dynamics in small-leaved linden plantations using multi-time Landsat images (forest case study from the Republic of Bashkortostan)

Abstract

The study analyses the above-ground phytomass of smallleaved Linden plantations (Tilia cordata) using GIS and remote sensing data. As these data are crucial for forecasting the dynamics of stand development in the future, they are also essential for evaluating the aboveground phytomass of tree plantations. As such, the analysis of these data is currently of great interest to the academic community. Research was carried out on plantations in which small-leaved Linden trees dominated. In order to evaluate the above-ground phytomass, the authors analysed the method of establishing test areas, as well as processed Landsat-5 and Landsat-8 images from different time periods. The authors used images of 1991 and 2020 to calculate the vegetation index values (NDVI). The research outcomes revealed a close correlation with the above-ground phytomass data obtained by the onsite surveying method (the coefficient of determination was equal to 0.68). In order to determine the above-ground phytomass of forest plantations based on the NDVI index, an exponential equation was calculated using the fundamentals of statistical processing. Thematic maps of above-ground phytomass obtained for 1991 and 2020 made it possible to analyse changes in the condition of tree and shrub vegetation over a nearly 30-year period. They also helped the authors identify areas in which the above-ground phytomass had significantly declined.