Fraxinus sogdiana Bunge forests in Charyn Canyon, Kazakhstan

This research investigates the biodiversity and ecological status of the Fraxinus sogdiana Bunge forests within Charyn Canyon, Kazakhstan, a unique ecosystem known for its high biodiversity and geological significance. Charyn Canyon, stretching for 154 km, contains over 1,500 plant species, 17 of which are listed in the Red Book of Kazakhstan. The relict grove of F. sogdiana occupies over 800 hectares of the 5,000-hectare floodplain area. The study assessed the photosynthetic parameters of Fraxinus L. and Populus L., measuring key indicators such as minimum fluorescence (Fo), variable fluorescence (Fv), maximum fluorescence (Fm), and chlorophyll content (mg m-²). Results show that F. sogdiana exhibited an Fv/Fm ratio of 0.735–0.828, indicating that some individuals are under stress. In contrast, Populus species showed higher photosynthetic efficiency with a maximum Fv/Fm value of 0.834. Floristic analysis revealed a complex plant community with significant species diversity, including xerophytes, mesophytes, and halophytes, indicative of the region's varied ecological zones. Vegetation indices derived from UAV mapping, including NDVI, GNDVI, and OSAVI, further supported these findings, showing higher photosynthetic activity and chlorophyll content in Populus than in Fraxinus. Correlation analysis between physiological parameters and vegetation indices highlighted significant relationships, particularly between NDVI and photosynthetic efficiency, providing insights into the health of the forest canopy. The study underscores the significant anthropogenic threats to the region, such as deforestation and uncontrolled grazing, accelerating habitat degradation, and reducing genetic diversity. The critical findings of this research underscore the urgent need for conservation efforts and provide a wealth of information that can guide these efforts, enlightening us about the state of these unique ecosystems and the measures needed to preserve them.