The influence of <i>Prosopis juliflora</i> on plant species diversity and community types of vegetation in Afar rangelands, Northeast Ethiopia

The structure and biodiversity of natural vegetative communities are increasingly threatened by invasive species. <i>Prosopis juliflora</i> is a major invasive shrub in Africa, Australia and North America. However, how its invasion is related to plant diversity and composition, and whether this varies with aspect, altitude, slope and anthropogenic disturbances (environmental factors) remains poorly understood. The aims of this study were to evaluate the relationships between <i>P. juliflora</i> invasion, floristic diversity and composition, and environmental factors in the Afar region of northeastern Ethiopia. The research examined two main hypotheses: (1) <i>P. juliflora</i> influences plant communities of the study area (2) native species diversity decreased with changing environmental factors. Sixty-four temporary sample quadrats were placed in woodland vegetation using stratified random sampling. Quadrats measuring 1, 100, and 400 m² were used to record the abundance and percent cover of herbs, seedlings and saplings and trees, respectively. Physiographic variables and human activities were also recorded in the 400 m² quadrats. Aspect, slope, grazing intensity, and disturbance showed positive effects on plant species diversity. However, plant diversity and composition were negatively affected by altitude, <i>P. juliflora</i> invasion levels, and anthropogenic factors. Three plant community types were identified using canonical correspondence analysis (CCA) and <i>P. juliflora</i> had a negative relationship with native plant diversity in the third plant community type. Revisiting quadrats or field in the future will provide evidence to support lower plant diversity as a cause or effect of <i>P. juliflora</i> invasion.