Invasives Blog

In the late 1970s and early 1980s the group of closely-related woody plant species and hybrids known as Prosopis were seen as a ‘saviour’ for millions of pastoralists and agro-pastoralists in East Africa whose very livelihoods were threatened by the degradation of dryland ecosystems spurred on by overgrazing, and by deforestation and a shortage of firewood.

Where the resources gleaned from dryland ecosystems in Ethiopia and Kenya constitute 35 percent and 50 percent of gross domestic product respectively, any threat to this valuable resource, also home to a range of wildlife and a magnet for cultural tourism, had to be dealt with swiftly.

In Ethiopia, for example Prosopis was introduced to curb desertification while in Kenya it was brought in to help alleviate the negative effects of deforestation. However, as Ketema Bekele, and his colleagues Jema Haji and Belaineh Legesse from Haramaya University in Ethiopia and Dr Urs Shaffner from CABI, reveal in a new paper in the Journal of Arid Environments, the future of Prosopis in these two countries could be short lived as the majority in two key areas are ready to invest in its downfall and eventual eradication.

Bekele et al, in ‘Economic impacts of Prosopis spp. Invasions on dryland ecosystem services in Ethiopia and Kenya: Evidence from choice experimental data’, for the first time sought to estimate the monetary values of ecosystem affected by Prosopis in the drylands of Afar National Regional State in Ethiopia and Baringo County in Kenya.

After surveying pastoralists and agro-pastoralists in both the aforementioned areas Bekele et al discovered Propsopis is no longer welcome and that local communities are more than ready to ‘cash-in’ and contribute both time and money to its management.

Once seen as a provider of shade, even a windbreak, and perhaps more importantly as a source of firewood, for charcoal production and construction material as well as a way to regulate microclimates, Prosopis is now seen as an ‘enemy’ to surrounding natural and semi-natural ecosystems. Specifically, its negative attributes, which are now seen to outweigh its benefits, include:

• Threatening biodiversity
• Reducing fodder for livestock production
• Causing groundwater depletion
• Its rapid encroachment into pathways, homesteads and water points limits mobility of animals and humans

Dr Schaffner said, “The underlying hypothesis was that the local communities in the study areas perceive that the negative effects of Prosopis invasion outweigh its positive effects and that they are willing to contribute to its management.

“Households from Afar were willing to contribute USD 50.42 per person and year for Prosopis invasion management options that will improve biodiversity, water availability, seasonal mobility and tourism flow.

“Meanwhile, households from Baringo were willing to pay USD 37.74 per person annually for Prosopis management options that will improve biodiversity and water availability. In both areas, microclimate regulation was acknowledged as a current ecosystem service by Prosopis – indicating that it does at least hold some value for the environment.”

Aside from the economic contribution, 74% of people surveyed in Afar were willing to help manage the plant with labour while 64% were like-minded in Baringo. The two most important ecological services that determined a willingness to participate in Prosopis management in both study areas were biodiversity and water – a desire to restore indigenous grasses and plant species richness and steps to improve water availability for home and livestock consumption.

The researchers also found that no single management option is favoured by everyone in the study areas. Instead Schaffner et al consider integrated and community-specific management options might be feasible – making reference to the recently-launched national strategy on Prosopis management in Ethiopia which calls for a coordinated and integrated management approach by different government and non-governmental development institutions.

Schaffner added, “Since Prosopis causes significant amounts of welfare costs, prompt actions should be taken to minimize its negative consequences on the pastoral and agro-pastoral livelihoods. Second, the estimated willingness-to-pay serves as a basis for allocating economically justifiable annual budgets for implementing sustainable control and management strategies in the two study areas. To address the shortage of wood in rural communities, efforts should be undertaken to combine grassland restoration with the planting of native trees”.

This research was carried out as part of the six-year project: ‘Woody invasive alien species in Eastern Africa: assessing and mitigating their impacts on ecosystems and rural livelihoods.’

The project aims to understand the impacts of woody invasive alien species on biodiversity, ecosystem services and human well-being and develop best management plans for these.

The international project team will be generating and sharing knowledge on how the invasive species establish and spread and on the effects and impacts of the invaders in the different contexts of Ethiopia, Kenya and Tanzania.

They will also be developing and improving measures for controlling the species, which will be built into Sustainable Land Management strategies that will help the countries to mitigate the impacts of the species.

Full paper reference:

‘Economic impacts of Prosopis spp. Invasions on dryland ecosystem services in Ethiopia and Kenya: Evidence from choice experimental data’, Ketema Bekele, Jema Haji, Belaineh Legesse and Urs Schaffner, Journal of Arid Environments (2018), https://doi.org/10.1016/j.jaridenv.2018.07.001

Donors

This work was supported by the Swiss Programme for Research on Global Issues for Development (r4d), funded by the Swiss National Science Foundation and the Swiss Agency for Development and Cooperation, for the project “Woody invasive alien species in East Africa: Assessing and mitigating their negative impact on ecosystem services and rural livelihood” (Grant Number: 400440_152085). http://www.besafe-project.net/news.php?n=164

Urs Schaffner was supported by CABI with core financial support from its member countries.