Effects of Prosopis juliflora Invasion on Native Species Diversity and Woody Species Regenerations in Rangelands of Afar National Regional State, Northeast Ethiopia

Abstract: Investigation of the invasion of Prosopis juliflora and its effects on indigenous plant species are important for the control of the species. The study aimed to assess: (1) the effects of Prosopis juliflora invasion on the diversity of plant species in Awash Fentale and Amibara Woredas; (2) the effects of Prosopis juliflora invasion on the regeneration potential of native woody species. Sample collection was performed in habitats of Prosopis juliflora thicket, Prosopis juliflora mixed with native species stands, non-invaded woodlands, and open grazing lands. The vegetation was stratified into invasion levels of Prosopis juliflora and then a random sampling technique for data collection. Among species of plants, the highest proportion of species, 75 (47.8%), was recorded under non-invaded woodlands, but the lowest proportion of species, 22 (14%), was recorded under open grazing lands. The invasion of Prosopis juliflora reduced the Shannon diversity index. The mean values of the Shannon diversity index and species richness under Prosopis juliflora mixed with native species (H′=2.22, R=14) and non-invaded woodlands (H′=2.23, R=13) were significantly higher than Prosopis juliflora thicket (H′=1.96, R=12) and open grazing lands (H′=1.84, R=10). The highest total density (358 stems ha–1) of seedlings was recorded under Prosopis juliflora mixed with native species. But, the lowest total density (153 stems ha–1) of seedlings was recorded under Prosopis juliflora thickets. Moreover, 102 trees ha–1 native woody species were recorded under Prosopis juliflora thicket, but 1252 trees ha–1 native species were recorded under non-invaded woodlands. If the invasion of Prosopis juliflora and its effects on native species diversity continue coupled with a drier climate, plant diversity of the Afar flora region will be highly affected and its ecosystem services will be under question. Thus, the participation of all stakeholders and multidisciplinary research approaches should be designed for the management of the species and rehabilitation of the rangelands in the region.