Muthono19/Vegetation-Productivity-Lengism

Analysis of Sentinel-2 NDVI time series to quantify vegetation seasonality, phenology, and seasonal productivity in the Lengism landscape of the Amboseli ecosystem (Kenya) # Vegetation productivity dynamics Lengism, Amboseli Stella Gachoki 2026-03-01 ## Introduction This analysis explores vegetation productivity dynamics in the Lengism landscape within the Amboseli ecosystem using Sentinel-2 NDVI time series. The workflow was developed using Python in Google Colab. It compares vegetation seasonality and productivity between 2020 and 2025 using monthly NDVI composites (accessed through Google Earth Engine), phenology metrics, and seasonal productivity estimates. ## Mean monthly NDVI The monthly NDVI time series and spatial composites together show a clear seasonal cycle in vegetation greenness across the study area, with higher productivity in the early months of the year and lower values during the mid-year dry period. In 2020–2021, vegetation greenness is already relatively high in February–March and remains stable through May before declining steadily toward a minimum around September–October, after which NDVI gradually increases again toward the end of the year. In contrast, the 2025–2026 period begins with lower greenness in February–March but shows a stronger and more spatially extensive peak in April–May, indicating a delayed but more pronounced greening phase. The composite maps support these patterns: darker green areas (higher NDVI) are more widespread during the peak months, particularly in April–May, while lighter tones dominate during July–October, reflecting reduced vegetation productivity during the dry season. Although both periods follow a similar seasonal trajectory, the timing and intensity of greening differ slightly, suggesting interannual variability in vegetation response likely linked to differences in rainfall timing and moisture availability. ## Vegetation phenology The phenological maps indicate a clear primary growing season across the landscape, but the second seasonal cycle appears weaker and more spatially heterogeneous. In both periods, **the start of the main season (SOS1**) occurs predominant …