Effects of Eucalyptus grandis invasion on native woody species richness, diversity, abundance, and composition in Kindoroko Forest Reserve, Tanzania

The effects of invasive plant species on native plant diversity are widely acknowledged, yet they remain under-studied in some mountain ecosystems in Tanzania. This study assessed the impact of Eucalyptus grandis invasion on woody species richness, diversity, abundance, composition, and overall plant community structure in the Kindoroko Forest Reserve (KFR), Tanzania. Vegetation data were collected from 60 concentric sample plots, categorized as invaded (22 plots) and uninvaded (38 plots), and analyzed for species richness, diversity, abundance, and composition. Cluster analysis, used to classify plant communities, indicated that while the presence of E. grandis did not significantly (p > 0.05) reduce species richness (34 vs. 47), Shannon diversity (2.11 vs. 2.26), or abundance (1071 vs. 1162) (p > 0.05), invaded plots consistently exhibited lower values compared to uninvaded plots, suggesting potential long-term effects on forest regeneration. The invasion also resulted in the formation of a distinct E. grandis-dominated community, highlighting its competitive advantage over native woody species. These findings indicate that E. grandis is altering the montane forest ecosystem of KFR and may threaten the unique biodiversity of the Eastern Arc Mountains. Therefore, management strategies to control its spread are urgently needed to safeguard the ecological integrity of this biodiversity hotspot. Key words: Biodiversity loss, forest disturbance, invasive species, Eastern Arc mountains, mountain forest, Mwanga District, wood species composition.