Using the One Health Concept to Assess the Multidimensional Impact of Invasion by Prosopis Trees

The One Health concept focuses on interactions between people, animals, plants and the environment, recognizing the interdependence of human, animal, plant and ecosystem health. This chapter applies the One Health approach to assess the effects of invasion by alien trees in the genus Prosopis on the four dimensions of health, drawing on research findings from eastern Africa and including, where appropriate, results from other parts of Africa. A review of the literature of Prosopis invasions shows that these invasions, while bestowing some benefits, have negative consequences on all dimensions of health, and that they are increasing in magnitude as the invasions grow. Negative consequences include injury and dietary or toxic impacts on people and animals, increase of vectors of zoonotic diseases, displacement of native plants through competition for limiting resources and allelopathy, and detrimental effects on the provision of ecosystem services by using excessive amounts of water and eliminating pasture grasses. This chapter proposes two approaches to assess the multidimensional impacts of Prosopis juliflora in a One Health context. First, an assessment of the impact of this invasive tree species on ecosystem service multifunctionality is presented, considering indicators of ecosystem services relating to all four dimensions of One Health. Second, the positive and negative aspects of P. julilfora are contrasted across the four dimensions to calculate a One Health score for different landscapes with varying degrees of invasion. Both approaches indicate that pristine or restored environments deliver positive benefits, but that heavily invaded sites are characterized by substantial changes in human, animal, plant and environmental health, a situation that is predominantly negative and unsustainable. Holistic assessments such as the approaches presented here will hopefully raise awareness of the gravity of the problem, thereby helping to secure the funding needed to contain and hopefully reverse the problems associated with these invasions.