Plant Species Composition, Richness, and Diversity in Areas Invaded by Non-Native Plants in the Lower Montane Forest of Kilimanjaro National Park, Tanzania

The present study assessed the impact of invasive alien species on plant species composition, richness, and diversity in the lower montane forest of Kilimanjaro National Park. The study area was categorized into four sites: the first three dominated by non-native species, namely Black Wattle (Acacia mearnsii), Mexican weeping pine (Pinus patula), and Eucalyptus (Eucalyptus spp.), and the fourth zone comprised natural forests. Sixty plots, each measuring 20 m × 50 m, were established at each site for vegetation sampling. A total of 168 plant species representing 135 genera and 64 families were identified and recorded from the study area. The highest plant species diversity was recorded in the natural forest with a mean plant species number of 13.8 ± 1.7, followed by Eucalyptus spp. A. mearnsii, and P. patula with 10.3 ± 1.2, 10.13 ± 1.1, and 7.33 ± 1.1, respectively. The plant species richness was significantly higher in the natural forest than in the areas invaded with non-native plant species (p P. patula site with a mean density of 12.7 ± 6.9. The reduction in plant species diversity and density in areas invaded with invasive alien species highlights the negative impact these species have on native plant communities. Sustainable forest management focusing on the protection of natural forests, the control of invasive species, and forest enrichment is highly recommended.