Distribution Patterns of Invasive Alien Species along An Elevation and Rainfall Gradient in Kenya and Uganda

Alien species distribution and population may be affected by topography and climate change. In this study we aimed to examine the effects of elevation and rainfall on invasive alien species diversity, richness and evenness in both terrestrial and aquatic habitats in Kenya and Uganda, through large scale elevation and rainfall gradient field investigation. We carried out survey in 82 regions which had an elevation that ranged from 855-4062m. We established 3 experimental plots in each region giving a total of 246 plots. In each plot we recorded species name, abundance, GPS coordinates, elevation and rainfall. We measured species diversity (Shannon and Simpson indices), species richness (Patrick index) and species evenness (Pielou index). We found that elevation and rainfall affected the invasive alien species diversity, richness and uniformity. The highest diversity, richness and uniformity was found at mid elevation (1500-2500m) and rainfall (1000-1500mm) and decreased at both lower and higher elevation and rainfall gradients. These results suggest that climate change may affect invasive alien plant species diversity in high elevation areas in Kenya and Uganda, which should be considered in the future management of plant invasions.