NDVI for Monitoring of the State of Steppe and Desert Ecosystems of the Gobi

Abstract

The current state of the dry-steppe, desert-steppe, mountain-steppe, and desert ecosystems of the Gobi Desert (Mongolia) has been studied. In the dry steppes and steppe deserts, not only is there a decrease in the phytocenotic indicators of plant communities and deterioration of the state of dominants, but also a change in their composition has been revealed. Thus, there was a replacement of typical grass species of dry steppes (Stipa krylovii, Agropyron cristatum, etc.) with desert-steppe species (Allium polyrrhizum). In steppe deserts, the role of herbal species (Stipa glareosa and Cleistogenes songorica) in the community structure significantly decreased, and the proportion of desert shrubs (Anabasis brevifolia and Salsola passerina) increased. The vegetation of true and extremely arid deserts turned to be the most resistant to aridization and increased pasture loads. The changes were revealed only in the Sympegma community, where a significant decrease in the abundance of Sympegma regelii was observed. A mismatch has been found between the values of the NDVI index obtained remotely from Landsat 8 images and the phytocoenotic indices determined in field studies. The data from field spectrometry of the dominant species and the surface of soils and plant communities showed that the soil background plays a significant role in formation of spectral images of plant communities, especially with low projective cover.