The belief of many people that every green vegetation is a perfect contributor of the 10 per cent forest cover is turning into an environmental farce.

This has become a matter of discussion among conservationists and government authorities in the country as they ponder on ways to control the invasive plant, Prosopis Jiliflora, popularly known as Mathenge, which is spreading at an alarming rate of 15 per cent per year.

The invasive schrub was introduced in Kenya back in1970’s to combat desertification due to its resilience, fast growth rate and its many uses for fodder, honey production, shade, windbreak, firewood, building poles, among other uses, but it has become a biological threat to the ecosystem.

“The tree has become not just a livelihood issue; it has become a threat to national security. The plant covers at least 4.9 million acres in 22 counties,” Environment and Forestry Cabinet Secretary Keriako Tobiko  has said.

Simon Choge Assistant Research Regional Director at the Kenya Forest Research Institute (KEFRI) reveals that the massive spread of mathenge was triggered by 1997 El Nino, which led to wide dispersal of the seeds.

Effects on animals

“The plant has been left unmanaged and has direct and indirect negative impacts to man and the environment, including colonisation and devastation of critical grazing land, farmlands and rangelands, blockage of roads, footpaths, human settlement, irrigation canals, river banks and water points and other habitats, death of livestock through over eating of pods (causing indigestion) and occasional tooth decay (due to high sugar content of pods) among others,” said Choge.

Choge warns that if it will not be contained, it has the capacity to replace the indigenous and other exotic trees in the country. “Mathenge is covering slightly above two million hectares (4.9 million acres) in 22 counties, which is about over two per cent of forest cover. We are afraid that if we do not manage it quickly, it might spread to other counties,” added Choge.

The largest biomass of mathenge in Kenya is found in Tana River,Turkana and Baringo, Taita Taveta, Malindi, Samburu, Isiolo, Mandera, Marsabit, Wajir, Kajiado and Migori Counties.

Choge reveals that the Mathenge menace is not only a Kenyan issue, but also a challenge in about half of the countries in Africa.

To address its spread,Tobiko reveals the government has developed a National Strategy and Action Plan as the solution to Prosopis, which lies in using it for production of charcoal, among other uses.

Forest cover threat

Environmentalists, however, have poked holes in charcoal burning as a tool to manage the spread of the shrub, and it might be a danger to the country’s forest and tree cover.

Daniel Wanjuki Director Ecosave Africa wonders how the government will differentiate charcoal from Mathenge and other trees.

“If there will be no proper mechanism to help in the implantation of this management strategy, other indigenous trees will be a target and this means the forest cover will be affected,” said Wanjuki.

According to the National Forest Resources Assessment Report 2021, Baringo County is at number 37 with a forest cover of 4.6 per cent far below the recommended level.

As per the report, Kenya’s tree cover now stands at 12.13 per cent while forest cover is at 8.83 per cent up from 5.9 per cent in 2018.

According to Choge, Mathenge is covering at least 2.2 per cent tree cover meaning if the country eradicates all Mathenge trees, the country tree cover will drop to at least 6.63 per cent. “As we cut the shrub for utilisation; let us not leave the land as bare as it was before the plant was introduced. Let farmers do it gradually by replacing it with indigenous trees, pasture and other crops,” said Choge.

Principal Secretary Dr Chris Kiptoo, however, said the utilisation of Mathenge must be done in accordance with the gazetted regulations.

Kiptoo said the regulations would take effect after local residents in Baringo and the other 21 counties affected by the invasive species sign the agreement prepared by the Ministry of Environment.

The agreement entails formation of Land Owners Association and Mathenge Charcoal Burners Association. “Those associations will work with County Government village elders and chiefs to ensure no other tree save for prosopis is cut down for charcoal burning,’’ he said.

But Baringo Governor Stanley Kiptis said the plant must be eradicated at any cost to prevent Baringo turning into a desert. “At the moment 71 per cent of Baringo is semi-arid and the trend is rising due to climate change. With the widespread plant, the challenge of desertification here is alarming,” said Kiptis.

Kiptis added that Prosopis growth showed that its invasive characteristics are best manifested in conditions of high water table in such areas as ravines, floodplains and swamps. “This leads to serious conflict with human activities. Mathenge has covered 7,000 acres of Perkerra Irrigation Scheme out of the total 11,000 acres,” he said.

Other important wetlands already invaded or with high potential of invasion include River Tana Delta, (Tana River County) Lorian Swamp (Isiolo/Garissa Counties) Lengurruahanga swamp (Kajiado) among others.

“The potential ecological disaster caused by prosopis invasion on the wetlands ecosystem is demonstrated by the near impossible complete eradication of the species once established,” warned Kiptis.

Meanwhile, another master plan to control and mange invasive species in Africa has been developed at a cost of US$1.4 trillion (Sh165.7 trillion).

Centre for Agriculture and Biosciences International (CABI) report says invasive plants has led to decreased productivity and limitation of the ability by producers to access export markets. “Through disrupting ecosystems, invasive plants, insects and diseases impair access to many of the human needs to sustain a good quality of life,  including food and shelter, health, security and social interaction,” said researcher, Johnson Kibera.

He said: “Invasive species alter and degrade the environment, and have a negative effect on both native species.”