Oops. A Mesquite Species Was Introduced To Kenya To Stop Erosion And Became A Full-On Environmental Catastrophe

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One of the main reasons the livestock of Lmakato, 48, crossed over into the conservation area was the mathenge, as the mesquite shrub (Neltuma juliflora, formerly classified as Prosopis juliflora) is known in Kenya. The grassland landscape is so dominated by inedible mathenge trees that cattle have to wander further to graze. Introduced in 1948, mathenge – a plant native to South America – became widespread throughout east Africa in the 1970s. It was seen as a remedy for creeping desertification, providing tree cover and preventing soil erosion in drylands, as well as a source of fuel and animal fodder. In Kenya, the UN Food and Agricultural Organization and the government actively encouraged its planting.

As the shrub spread, it quickly became a nightmare. A closely related species is now considered one of the world’s worst invasive floral species. Since its introduction, mathenge has spread across the country, and nearly three-quarters of Kenya is at risk of being invaded. It has colonised large swaths of the country’s arid and semi-arid regions, choking vast rangelands and drawing moisture from the soil with its deep roots. The Kenya Forestry Research Institute (Kefri) estimates it has encroached on 2 million hectares (7,700 sq miles). According to Kefri scientists, it is spreading at a rate of up to 15% a year.

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“The spread is so fast that it has caused entire communities to be displaced, schools to close, and even disrupted river flows, as the plant blocks watercourses – contributing to flooding and displacement,” says Davis Ikiror, Kenya-Somalia country director for Vétérinaires Sans Frontières (VSF) Suisse, an organisation that has worked in Kenya for more than two decades. In Samburu county, where more than 60% of the population are pastoralists and 30% mix herding with small-scale farming, livestock is a lifeline. Some animals die from mathenge toxicity after ingesting it in large amounts. While grazing, the plant’s tough thorns injure the animals by lodging in their feet and its sweet pods – high in sugar – cause dental decay and the loss of teeth among the animals.

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But to rein in the plant’s spread, larger interventions will probably be required. Mathenge’s deep root system, reported to go as down as far as 35 metres below ground, siphons off precious water that other species require. Its branches grow so thickly and its roots are so deep that an incursion can even alter the course of rivers. In some parts of Isiolo, such as Ires a’Boru, displacement of water beyond the banks caused flooding that forced communities to relocate. The slowed water flow and dark canopies create ideal breeding grounds for mosquitoes – which worsen the spread of malaria and Rift Valley fever, and kala-azar, or leishmaniasis, which is carried by sandflies. The plant’s chokehold has wrought havoc on biodiversity. Once seeded, it forms a dense canopy that stops other plants growing by blocking out light, says Douglas Machuchu, project manager at VSF Suisse.

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https://www.theguardian.com/environment/2025/may/22/kenya-mathenge-desertification-invasive-plants-neltuma-prosopis-juliflora-samburu-pastoralists-aoe

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1. Interesting the environmental disaster of

introducing a few lake trout into Yellow Stone Lake. Bear, elk, down to plants and bugs.