Distribution and socio-ecological impacts of the invasive alien cactus Opuntia stricta in eastern Africa
Published: May, 2017
Many cactus species have been introduced around the world and have subsequently become major invaders, inducing social and ecological costs. We recorded the distribution of Opuntia stricta in eastern Africa, and conducted 200 household interviews using semi-structured questionnaires to assess local perceptions of O. stricta in Laikipia County, Kenya. Opuntia stricta was widespread and abundant in parts of Kenya, Tanzania and Ethiopia and present at low densities in Uganda. In Laikipia County, pastoralists identified that O. stricta had been present for more than 10 years, and were of the opinion that it was still spreading and increasing in density. Two-thirds of respondents estimated that 50–75% of valuable grazing land had been invaded, and all felt that it contributed to the ill-health and death of livestock. Other negative impacts included reductions in native plant populations, rangeland condition, human health, and mobility of humans and animals. These negative impacts resulted in economic losses of US$ 500–1000 per household per year for 48% of households. Only 20% of respondents reported actively managing O. stricta, yet all respondents believed a reduction in the abundance of this weed would improve well-being. Management interventions are needed to reduce negative impacts.
The global cost of invasive species is estimated at US$1.4 trillion per year – close to 5% of global gross domestic product. Invasives disproportionately affect vulnerable communities in poor rural areas, especially in developing countries which depend on natural resources, healthy ecosystems, trade and tourism for their livelihoods.
Start: 02/01/18 -End: 31/03/21
Many exotic plant species introduced to Laikipia County, Kenya, have escaped cultivation and threaten biodiversity. Little is currently known however, about the presence of invasive species or their impact. Without this type of information, it is unlikely that various stakeholders will take action to effectively manage this threat. This project aims to fill some gaps and increase knowledge of invasive species in Laikipia for pastoralists and those actively involved in biodiversity conservation.
Start: 01/01/13 -End: 31/03/17
Pastoralists in northern Kenya are heavily dependent on livestock. Their lives are being devastated by the non-native cactus Opuntia stricta. This weed has invaded the last good grazing land and when livestock and wildlife eat its fruits the spines can cause infection and death. Chemical and mechanical control methods are expensive and impractical, so we are helping to introduce a new sustainable method: a sap-sucking insect that feeds solely on the cactus.
Start: 01/01/12 -End: 31/12/17