Understanding vegetation change in northern Tanzania: interactions between climate variability and human activity

Abstract

Changing climatic patterns and allied hydrological variability have substantial impacts on regional vegetation growth. This study provides a comprehensive assessment of long-term climate change, anthropogenic activities, and corresponding vegetation dynamics by utilizing multiple remotely sensed datasets and employing various statistical approaches and modeling techniques at annual, seasonal, and monthly scales from 2000 to 2022. Non-parametric trend analyses indicate a significant increase in air temperature (0.25 °C/year, p < 0.05) and a notable decline in rainfall (−33.7 mm/year, p < 0.05), alongside increases in potential evapotranspiration and decreases in both soil moisture (−1.3 mm/year) and groundwater storage (−1.52 mm/year). These climatic and hydrological changes exhibit strong associations with vegetation cover. A significant reduction in regional greenness, as indicated by the Enhanced Vegetation Index (EVI = −0.62), is observed primarily in the lowland plains of northern Tanzania, while slight increases are noted in higher-elevation regions. Additionally, anthropogenic activities also play a critical role in regional vegetation degradation. Approximately 80 % of the vegetation loss in the southeastern plains is attributed to unsustainable human activities. The study revealed a strong positive correlation between rainfall and vegetation productivity (R² = 0.91, p < 0.05), whereas temperature shows a significant negative correlation (R² = −0.81, p < 0.05). Notably, the observed decline in EVI is closely linked to reduced rainfall (R² = −0.79, p < 0.05), emphasizing the pivotal role of climatic parameters in influencing vegetation dynamics. Quantifying these variations in relation to climatic, hydrological, and anthropogenic drivers is essential for the development of effective and sustainable vegetation restoration strategies.