Effects of prosopis juliflora on plant diversity on rangeland in Shilabo District, Somali Regional State, Ethiopia

Shilabo District of Somali Regional State in Ethiopia is economically important for livestock production. The indigenous pasturelands are increasingly being invaded by Prosopis juliflora, thereby threatening their livestock production capacity. However, the ecological impact of Prosopis' invasion has yet to be investigated. This study was conducted to examine the effects of Prosopis juliflora on plant species abundance, diversity, and occurrence. Vegetation samples were collected from three 20-m by 20-m sub-plots nested within 100-m by 100-m main plots that were purposefully selected in target study sites and replicated three times in both invaded and uninvaded areas. The study recorded 44 plant species, of which thirteen species occurred in both invaded and uninvaded areas, 13 species in invaded areas and 24 in uninvaded areas. The collected data were analyzed using the Statistical Package for Social Sciences (SPSS) version 26, and an independent t-test was used to determine the statistical significance difference between invaded and uninvaded areas in terms of number, density, important value index, diversity, abundance, evenness, and richness of plant species. These plant parameters were recorded in invaded and uninvaded areas with species numbers of 678.33 and 1763, densities of 226.00 and 366.98/ha, abundances of 254.04 and 409.45, important value indexes of 15.00 and 9.68, Shannon diversity of 1.56 and 3.40, evenness of 0.52, and 0.99, and richness of 1.30 and 1.35, respectively. The uninvaded area had a significantly higher species diversity index (3.40) than the invaded area (1.56; P 0.00). Similarly, the number of plant species, density, abundance, important value index, species evenness, and richness were significantly higher in uninvaded areas than invaded areas (p < 0.000).