Economic impacts of Prosopis spp. invasions on dryland ecosystem services in Ethiopia and Kenya: Evidence from choice experimental data

Abstract

Biological invasions can induce trajectories of changes that make ecosystems fragile and less reliable in providing services and goods. Here we set out to assess the economic value of dry land ecosystem services affected by the invasive tree Prosopis, which was originally introduced in Africa and elsewhere for providing firewood, animal fodder and other services to rural people. Based on choice experiment method, we estimated the economic values of dry land ecosystem services affected by Prosopis in the heavily invaded Afar region, Ethiopia and Baringo County, Kenya. Including labor and cash contributions as payment attributes, a random parameters logit model was employed for analyzing households' preferences for the affected ecosystem services. We found that, despite the services provided by Prosopis, households from both regions were willing to pay for its management primarily driven by biodiversity and water. WTP was on average higher in Afar (USD 50.42/year) than in Baringo (USD 37.74/year), which may be because the ecosystems in Afar were less degraded prior to the invasion by Prosopis than in Baringo and that charcoal production in Afar is officially prohibited. Our results indicate that the costs imposed by the deliberately introduced Prosopis outweigh its benefits in both Afar and Baringo.