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Opuntia Engelmannii Cactus in Loisaba “From Invasive to Productive”

Conservancies are not only responsible for protecting native species and resources; but are also tasked with managing problematic invasive plants, which affect both humans and wildlife.

In northern Kenya, in Loisaba specifically, we have been plagued by the fast-spreading, land-guzzling Opuntia Engelmannii, or the “prickly pear cactus”, originating from north America, since the 1950s. With few natural predators, the cactus has ravaged thousands of acres of preserved and pastoral grazing land in Loisaba. Aided by the movements of elephants and baboons, who enjoy the fleshy, edible fruits, this invasive species is on the road to becoming an ecological disaster.

There is a plethora of ways in which one can manage invasive species, whether by mechanical, chemical, or biological controls. Every situation is different, and the selected method needs to maintain the integrity of the land as much as possible.

In Loisaba, we have created a multi-faceted approach, using both mechanical and biological controls. On the mechanical front, farmers and local community members carry wheelbarrows full of the spiky plants to our crusher, into which one of our staff members dumps the loads of cacti. With a bit of added water, the plant is crushed up and becomes a semi-solid form. The liquid is left to ferment for about a week, which then produces methane gas, a source of clean biogas that runs the staff kitchen for around 7 hours per day. The liquid biproduct from the fermentation process is also used as fertiliser.

This project was launched in 2019 and has proved to be a multi-layered success. Not only are the Opuntia Engelmannii manually cleared away, allowing wildlife and pastoralists to reclaim the prime grazing land, but clean energy is also generated, a process that can be shared with the local community in due course.

In terms of the biological control, we have recently been approved (by KEPHIS, the Kenya Plant Health Inspectorate Service) to introduce a cochineal bug into the ecosystem, which will be able to manage the spread of the cactus.

While the prickly pear cactus has wreaked havoc in many areas of Africa, we celebrate this innovative method that not only removes something negative from the environment; but also adds something positive for local communities.

This marriage of ecological and social benefits is the cornerstone of any successful conservancy.

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