Spatiotemporal NDVI Analysis of Kipengere Forest Reserve Dynamics in Tanzania: Evidence from 1995 to 2026

Forest ecosystems are of great importance for biodiversity conservation and water resource regulation but are increasingly subject to environmental and land-use changes. The study analysed the spatiotemporal dynamics of vegetation condition in the Kipengere Forest Reserve, Southwest Tanzania from 1995 to 2026 using the Normalized Difference Vegetation Index (NDVI) generated from Landsat satellite images. Using QGIS, Landsat 5 imagery of March 1995 and Landsat 9 imagery of May 2026 were processed and analysed. The NDVI values were classified into five vegetation-condition categories ranging from very low to very high density and the changes in their spatial coverage were quantified. The results indicate that there is a significant change in the vegetation condition over the 31 years. In 1995, 45% (15,835.50 ha) and 45% (15,801.21 ha) of the reserve was covered by moderate and relatively dense vegetation, respectively, with 3.86% (1,354.24 ha) covered by dense vegetation. Moderate vegetation increased to 73.6% (25,841.30 ha) in 2026 and relatively dense vegetation decreased to 17% (6,058.83 ha). Vegetation cover dropped to 1% (386.73 ha). Very sparse and sparse vegetation increased marginally. Generally, the results suggest a transition from higher density vegetation to predominantly moderate vegetation, indicating reduced vegetation density and greenness. Although specific drivers cannot be identified, it is recommended to have continued monitoring and investigation of land use change, human activities, climate variability, fire, and other environmental factors. The results offer a baseline for conservation planning and sustainable management of the reserve and its related water resources.