The Indian weed choking Mount Kenya forests

John Mwithimbu shows the extent of destruction caused by Lantana camara in Imenti forest. [Caroline Chebet]

For years, Mt Kenya forests, the country’s main water tower, have struggled against degradation caused by illegal logging.

But now, conservationists are coming to grips with a second villain; Lantana camara, also known as Curse of India, a fast-growing, tough-to-control shrub that is suffocating large sections of the forest.

The plant is an aggressive invasive weed which although is not native to Kenya, has been famously used to fence. Lantana is currently spreading over Mt Kenya forests, colonising chunks of forest land and driving elephants out into farmlands.

“Lantana camara is currently the biggest nightmare in Mt Kenya forests. It is taking over these iconic forests and choking young trees from sprouting. It is the current biggest threat,” Kennedy Riungu, Lower Imenti forest station manager said.

Riungu said the plant has already colonised several areas in Nyambene Hills, Ngaya Forest, Upper and Lower Imenti, adding that eliminating the plant is currently the biggest hurdle.

“The plant is very aggressive. When removing them, it is first cut, uprooted and the area should be weeded several times to completely get rid of it. Since it is a prolific seeder, it has a huge seed bank in the soil, a situation which makes it even harder,” Mr Riungu said. The elegant yet extraordinarily tall Meru Oaks on the edges of Imenti forest in Mt Kenya betray the challenges inside one of Kenya’s main water towers.

Inside these critical forests recognised as a World Heritage Site, deforestation and Lantana camara is a threat.

Ornamental shrub

According to Centre for Agriculture and Bioscience International (Cabi), Lantana camara is widespread in Kenya.

It was introduced in the country in the 1950s as an ornamental shrub and has since been reported as extremely weedy and invasive. It is ranked among the top 100 invasive plants in the world.

Cabi notes that besides being reported as an agricultural weed resulting in large economic losses in a number of countries, Kenya included, it also increases the risk of fire and is poisonous to livestock. It is also a host for numerous pests and diseases and is hard to control.

Already, Lantana has taken over 1200 hectares of Upper Imenti, 1500 hectares in Lower Imenti and 500 hectares in Ngaya forest. It has also taken over 500 hectares of Nyambene Hills. While the plant grows to create its own impenetrable thickets that bar animal movements in the forest, it also grows to climb and strangles other trees to create its own canopies. This also means that it bars younger trees from growing making natural regeneration a challenge.

The cost of removing Lantana in Mt Kenya, according to Kenya Forest Service (KFS), is an expensive venture. The breakdown indicates that over 60 people have to work on an acre a day just to cut down the thickets which are hard to penetrate through. Each of the workers is paid Sh400 a day translating to Sh240,000 per day to clear an acre of the invasive weed. The weed is then uprooted, where not less than 32 people are required to dig out an acre in a day.

“All this exercise is carried out with caution. Not a single stick is left behind because once it falls, it sprouts back. It is a tedious job and that is why partnership is key in restoring the degraded parts,” Riungu said. To completely eradicate the weed, the area requires maintenance which is carried out thrice a year. This means that per acre, 40 people are required to weed to completely destroy the already sprouting plants from the rich seed bank in the soil.

Biggest menace

“The main reason Lantana is the biggest menace in Mt Kenya forests is that it prevents natural regeneration meaning that when older trees die off, Lantana thickets take over. The only solution at the moment is to uproot Lantana but then it prickles and people tend to shy away from taking the job because it is tedious. It is also very expensive to get rid of the plant,” Meru County Ecosystem Conservator John Njoroge said.

The situation in Mt Kenya forests is becoming widespread such that whenever it rains, immediately Lantana springs up even within areas that it never existed because of the huge seedbank in the soil.

“All the seeds that had been dormant in the soil spring up, that is why we have to keep reclaiming the areas until it is completely out of the forest. However, we cannot do it alone because it is an expensive venture, we engage organisations to adopt sections to reclaim,” Mr Njoroge added.

And while efforts to manually remove the weed have been promoted in the forests, Trees Establishment and Livelihood Improvement Scheme (Telis), according to the foresters, greatly helped in restoring degraded areas.

In the scheme, farmers living adjacent to the forests are allocated small parcels of land within the forest to remove the weed and cultivate. In exchange, they plant trees within their plots and care for them until the canopy begins to close. Often, according to Mr Njoroge, it takes three years for the canopy to close. However, Telis has since been stopped since the logging moratorium that came to force in 2018.

“Telis helped a lot in restoring the degraded areas because farmers also benefited while also planting and tending the trees. It is also a cheaper way to deal with the challenge,” he says. 

Ecosystem assessment conducted by Nature Kenya, a conservation organisation, indicated that 6,200 hectares in Mt Kenya forests are degraded and require urgent restoration. KFS said until the government takes a position, they have to depend on partnerships and organisations to mobilise funds and adopt sections of the forest to rehabilitate.

Paul Gacheru, a species expert at Nature Kenya, said besides the invasive weed being a challenge in Mt Kenya ecosystem, deforestation is also part of the challenge. The organisation, Mr Gacheru says, has since been creating linkages and building capacities with the community forest associations so that they can be able to mobilise for resources locally.

Through such partnerships with public and private business sectors such as Kenya Breweries Limited, Safaricom and Coca Cola rigorous activities geared at restoring degraded areas within Mt Kenya have taken shape.

“The aim is to create a model in Mt Kenya where public and private sectors come in with concerted efforts towards restoring the key critical water tower. Community forest associations are also trained on ways to mobilise resources,” he said.

Through funding from international partners like Darwin Initiative and World Land Trust, he says, restoration initiatives have taken a shape in Mt Kenya ecosystem with communities and schools being part of those conserving the forests.

“Schools and families bordering the forests have been engaging in conservation initiatives through the adoption of energy-saving cook stoves,” Gacheru said.

Gacheru added: “Lantana is a very difficult weed. A lot of money has been used in getting rid of the weed and restoring degraded areas, but is not sustainable. Nature Kenya has also written to KFS to allow and advise on something which might be cost effective in restoring the forests,” Meru County Environment and Wildlife Chief Officer Lawrence Kinoti said Mt Kenya ecosystem is critical and supports many rivers. Lower Imenti, Mr Kinoti said, plays a critical role as a migratory corridor to elephants.

“Partnerships have really helped us to restore these forests. We have been able to bring several organisations on board through community forest associations. Companies including Kengen, Eden, Mt Kenya Trust, Nature Kenya, Safaricom, Coca Cola and KBL among others have really helped,” he said.

The challenge posed by Lantana in some areas has also resulted in an intense human-wildlife conflict where elephants stray into people’s farms because of the impenetrable thickets in the forest. Lantana leaves are also not edible; a reason elephants are pushed out of the forest.