Impact of logging on the tree species diversity and abundance in Mabira Central Forest Reserve, Uganda

Abstract

This study assessed the impacts of logging on tree species diversity and their abundance in Mabira Central Forest Reserve (MCFR). This was achieved by comparing tree species diversity and abundance in an unlogged compartment (inviolate/strict nature reserve) and part of the forest reserve where active logging was in progress. Three transects each measuring 1km were laid in each site and 24 quadrat (20 x 20m) were established in both logged and unlogged areas using systematic sampling technique, with trees of at least 10 cm diameter at breast height (DBH) identified, measured, and recorded. A total of 49 different tree species were identified in both sites, 32 tree species were common to both sites (logged and unlogged), 11 tree species in the unlogged site and 6 tree species in the logged site. The findings revealed a decline in species diversity and tree abundance in logged areas, with a 2.9% reduction in the Shannon-Weaver diversity index. Logged areas were dominated by small diameter trees (11-20 and 21-30cm DBH), suggesting rapid regeneration but at the cost of losing mature, slow-growing species that are essential for long-term ecosystem stability. In contrast, unlogged areas had higher species richness and tree density with larger trees, supporting a more intact and balanced forest structure. Statistical analysis (Z-test, p < 0.05) confirmed significant differences in tree abundance between the two sites, reinforcing the detrimental effects of logging on MCFR’s biodiversity. The study highlighted the urgent need for sustainable forest management practices, stricter enforcement of conservation policies, and community-driven reforestation programs to curb the negative effects of logging. If unregulated logging continued, MCFR would face further degradation, diminishing its role in carbon sequestration, climate regulation, and habitat provision for wildlife. The study recommended stricter enforcement of logging regulations, enhanced reforestation initiatives and community involvement in conservation efforts to ensure the long-term sustainability of the forest. The study concluded that logging activities have negatively affected tree species diversity and their abundance in Mabira Central Forest Reserve and protecting MCFR is critical for preserving its role in climate regulation, water catchment stability, and as a habitat for diverse plant and animal species.