On the possibility of estimating the aboveground phytomass of steppe vegetation using color vegetation indices (based on survey data from unmanned systems)

Productivity indicators are one of the priorities in the study of steppe ecosystems, rational nature management and sustainable economic development. The article presents the results of assessment of the relationship between the amount of aboveground phytomass of fallow and indigenous steppe communities of Transbaikalia with aerial photography data from an unmanned aerial vehicle, as well as NDVI data from Terra and Aqua satellite images. The studies were carried out in two key areas of the model polygon during the growing season of 2018 - a total of 10 observations were made, including accounting for phytomass and survey of the study area. The calculation of color vegetation indices ExG, ExR, ExGR, NDI, NDYI was carried out according to orthomosaics obtained as a result of processing aerial imagery. Correlation analysis revealed that ExR and ExGR are the best indices for estimating the amount of aboveground phytomass. MODIS NDVI showed a high dependence on productivity - the correlation coefficient reached 0.98. There is a close correlation between the phytomass and the hydrothermal coefficient - up to 0.95. It was found that the values of the indices at different key areas are statistically not dissimilar. We have concluded that it is necessary to use large-scale vegetation maps to assess the productivity of the steppe using colored indices.