Above ground biomass, land cover change and regeneration of tree species under different grazing intensities in miombo woodlands,Tanzania

MSc Dissertation

Tanzania's livestock sector faces challenges due to overgrazing, threatening the ecological balance of critical habitats like Miombo woodlands. This study investigates the impact of grazing pressure on land cover changes, tree biomass, and regeneration potential in these woodlands of Kilosa, Kilombero, and Handeni districts. Despite existing research on the damaging effects of overgrazing, a comprehensive analysis specific to Tanzanian Miombo woodlands is lacking. We address this gap by analyzing high-resolution satellite imagery (Landsat 5 TM & 8 OLI) from 1995 to 2021 to quantify land cover changes across the study areas. Field surveys were conducted to assess grazing intensity, aboveground biomass (AGB), and tree regeneration within representative Miombo woodland sites. Allometric models estimated tree-level AGB, which was then scaled to calculate plot-level AGB (tonnes/ha). Statistical analyses explored relationships between grazing intensity and land cover change, biomass dynamics, and tree regeneration. Results reveal a negative impact of medium and high grazing intensities on AGB compared to light grazing. Satellite image analysis indicates higher tree cover loss under medium grazing (63.5%) compared to high (61.5%) and light grazing (23.2%) between 1995 and 2022. Additionally, grazing intensity significantly affects tree regeneration (number, species richness, diversity, and evenness) (p < 0.05). These findings show the damaging effects of overgrazing on Tanzanian Miombo woodlands. This knowledge can inform sustainable grazing practices, collaborative management strategies, and efforts to mitigate forest cover loss. Further research could explore optimal grazing levels and develop specific recommendations for policymakers and land managers.