The potential economic implications of Robinia pseudoacacia L. (Black locust) on agricultural production in South Africa

The potential economic implications of Robinia pseudoacacia L. (Black locust) on agricultural production in South Africa
Grant D. MARTIN, Luke Humphrey, Gavin Fraser
Biological Control Research Group, Department of Zoology and Entomology, Rhodes University, Grahamstown

Robinia pseudoacacia is an invasive deciduous, strongly suckering, broad-leaved tree that has the potential to further its distribution across a large portion of South Africa. Black locust has already invaded all nine of South African provinces. The invasive trees potential to spread into livestock grazing lands in South Africa has not been investigated. The potential economic impacts of R. pseudoacacia on agricultural production stem from the trees ability to reduce the carrying capacity of livestock. This study estimated the potential economic implications of R. pseudoacacia on agricultural production in South Africa, specifically looking at the livestock sector. The prevalence of R.pseudoacacia potential distribution was calculated by using a maximum-entropy predictive habitat model, MAXENT. The distribution of livestock, based on grazing capacity (ha/LSU), in South Africa was then determined. The potential direct economic impacts were estimated by assessing the impact of the potential distribution of R. pseudoacacia on the carrying capacity of livestock. The results showed that an infestation of R. pseudoacacia has the potential to reduce the gross margin in the livestock sector from approximately R130 million to R961 million, dependent on the probability of invasion. Therefore, R. pseudoacacia can have detrimental effects on the livestock sector in South Africa. The potential high levels of foregone income and business activity found in this study reaffirm the need to devote resources to develop a viable, economical and effective control methods