Decoding Vegetation Dynamics in High-Altitude Tropical Ecosystems: A Spatio-Temporal Assessment Using Multi-Index and Biophysical Remote Sensing Products (2002–2024)

Abstract High-altitude tropical ecosystems like the Rwenzori Mountains are increasingly vulnerable to the impacts of climate change and intensified human activity. This study investigates long-term vegetation dynamics in the Rwenzori Mountains using time series remote sensing data from 2002 to 2024. Specifically, four vegetation indices and biophysical parameters, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Leaf Area Index (LAI), and Fraction of Photosynthetically Active Radiation (FPAR), were analyzed to assess spatial and temporal trends and identify ecological stress patterns. Using hotspot analysis and trend detection, we observed marked spatial heterogeneity in vegetation health. Coldspots, often located above 3000 m or in lowland areas with high human activity, showed persistent vegetation decline. In contrast, hotspots between 1400 and 2800 m in the northeastern, eastern, and southern regions indicated relatively stable and healthy vegetation cover. Temporally, significant negative trends were detected in FPAR during December and in both FPAR and LAI during the Dec–Jan–Feb (DJF) season, suggesting seasonal ecological stress. While some positive but statistically non-significant trends were recorded in June and September, NDVI revealed a consistent and significant annual decline, indicating long-term vegetation degradation. These findings underscore the pressing need for sustainable land use and conservation strategies to protect high-altitude tropical ecosystems from ongoing ecological decline. Graphical Abstract