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

Abstract

Black Locust (Robinia pseudoacacia L.) is an invasive deciduous, strongly suckering, broad- leaved tree that has the potential to be widely distributed across a large portion of South Africa. Robinia pseudoacacia has invaded all nine of South African provinces, with large infestations found in the Eastern Cape, Kwa Zulu-Natal, Free State and Gauteng provinces. The invasive tree has the potential to spread into livestock grazing lands in South Africa. Because R. pseudoacacia has the ability to spread and thrive in a variety of habitats and resists control, the distribution of the invasive tree into grazing land poses a problem for landowners. 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 by between approximately R130 million and R961 million, dependent on the probability of invasion. Therefore, the potential invasion of 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 method, such as biological control.