20/05/16
Alien plants turn East Africa into ‘green desert’
The Opuntia stricta cactus, known as the erect prickly pear, is native to the Americas. It was introduced to East Africa decades ago as an ornamental plant, but has since spread throughout the continent with a devastating effect on people’s lives, reducing land productivity and harming livestock
CABI
Pastoralists in Laikipia county in central Kenya depend on their biodiverse habitat for their livelihood. But the land is being overrun by prickly pears, threatening the way of life of Maasai herdspeople and their families
CABI
The cactuses’ spines can blind or otherwise seriously injure livestock foraging near the plants. When goats, sheep and other animals try to eat the plant’s fruit, the spines can cause painful abscesses, which inhibit feeding
CABI
With the Kenyan government’s permission, not-for-profit CABI (Centre for Agriculture and Biosciences International) introduced this type of cochineal to Laikipia county to control the cactus. The female produces a protective thick white web and sits underneath it. It kills Opuntia by eating its flowers and fruit
CABI
Woody plants such as Prosopis juliflora, which here surrounds a home, are aggressive invaders originally from Mexico, South America and the Caribbean. Large programmes have been rolled out to mitigate their harm, but in East Africa, where villages are more vulnerable to invading species, Prosopis is still difficult to control
CABI
A farmer holding a Prosopis branch explains how difficult it is to live with this invasive weed, whose uncontrollable proliferation can displace entire communities
CABI
George Achilla is a farmer in the Kenyan village of Kikopey. He grows crops to feed his family and make a small profit. But his land has recently been overrun with Parthenium. He spends a large part of his day removing the shrub from his farm to make space for vegetables and livestock
CABI
In Kenya, Parthenium has taken over large areas of land, displacing existing plants and animals, and creating green ‘deserts’ where little else will grow
CABI
Parthenium is native to the American tropics, but it was accidentally introduced to other continents and now severely threatens native biodiversity in Africa, Asia and Australia. Its resilience enables it to grow almost anywhere and it spreads rapidly
CABI
The Parthenium beetle is used as a natural control against Parthenium. The insect is also known as the Mexican beetle in reference to its country of origin. It eats the plant’s leaves, curbing its growth and flower production
CABI
By: Lou Del Bello
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Invasive species can have unpredictable impacts on new habitats. They can alter the food chain, and overpopulate entire regions at the expense of local animals and plants.
Living creatures have always moved at different rates around the planet. But human transport can rapidly carry animals and plants around the world. Those who thrive in new places will irreparably change local biodiversity.
In East Africa, the proliferation of alien plants such as Opuntia stricta, Prosopis and Parthenium, all captured in this photo gallery, threaten the livelihoods of farmers and rural communities.