ESTIMATION OF ENVIRONMENTAL AND ECONOMIC COSTS ASSOCIATED WITH ENCROACHMENT OF WOODY INVASIVE SPECIES IN THE BORANA RANGELAND, SOUTHERN ETHIOPIA: USING PARTICIPATORY APPROACH

. Currently, woody invasive species cause for environmental and economic impacts and effect on country gross domestic product. This is observed in Borana rangeland where several woody invasive species infestation happened. This paper aimed to estimate environmental and economic cost of woody invasive species focusing on its distribution and abundance using participatory survey approaches. This approach estimates an average cost for each species by a ratio of management costs, and the annually expenditures incurred by a variety of households. Twelve (12) dominating woody invasive species were recorded in Borana rangeland that are encroached major part of grazing area and Acacia species are the most dominant one. Annually, from each household an estimated total of $29.9 million or 1.1 billion Ethiopian birr economic cost was recorded due to encroachment of woody invasive species and annual economic cost per person was around $424 or 15,137 Ethiopian birr. Cost estimates are the highest for Acacia species ( Acacia drepanolobium, Acacia bussei and Acacia mellifera ) accounting for 66% of the total estimated economic cost, followed by Capparis tomentosa, which also adversely impacts on ecological services. Such economic cost assessment of woody invasive species used as a monetary basis for ranking the species based on their impact and take prioritizing management actions. Further, the cost estimate approach used in this study could help as a model for woody invasive species economic impact assessments in other part of the rangeland area.