- An invasive species of mesquite named Prosopis juliflora, and known in Kenya as mathenge was introduced to the region to restore degraded drylands.
- Residents describe mixed feelings about whether to keep the mathenge tree or try to eradicate it. Some termed it a “dryland demon” — since it can inflict injuries in both people and livestock, while blocking paths where it formed canopies.
- Using charcoal production to both curb the spread of the prolifically invasive plant and reduce demand on native species is consistently described as a positive development by proponents.
In the town of Turkwel in Kenya’s vast Rift Valley region, 45-year-old Esther Aboi is busy placing pieces of wood inside her homemade kiln.
The smoking firewood is an invasive species of mesquite named Prosopis juliflora, native to Central and South America and known in Kenya as mathenge. Finding the tree is no struggle. It grows in such abundance here that Kenya’s Environment and Forestry Ministry calculated that Turkana county, where Turkwel is located, could meet the national demand for charcoal from its existing stands of mathenge.
The landscape in Turkana is characterized by rugged dry terrain with sparse vegetation. Yet the residents here see major downsides associated with having the most mathenge trees in the country — an estimated 3,300 square kilometers (1,300 square miles), double the size of Kenya’s famed Masaai Mara National Reserve.
“The mathenge tree is dangerous,” Aboi tells Mongabay. “It has deformed the teeth of camels, goats and donkeys.” The tree’s pod is sugary, contributing to tooth decay in grazing animals. And overconsumption of the pods in the absence of grass has been found to kill livestock through indigestion. The thorns are equally harsh.
“Mathenge has destroyed our farm. We use mathenge because it is the only tree that survives here,” Aboi explains as she walks around her homestead. Her house is built with mathenge wood, as are the livestock shed and the fence surrounding the land. Life seems to revolve around the notorious invader.
“You look around and think Turkana is very green, but it is not,” Aboi says while overlooking Turkwel Hill. The vegetation is verdant, but the soil is sandy, loose and dry under the scorching sun. The wind whips it up into dust storms that hit the villages. Mathenge exudes a rich green color, a rarity in an otherwise arid environment. The color is so striking and yet so deceptive, as other plant species are choked out by the impenetrable thickets of the thorny tree.
Introducing an invader
Among the reasons for introducing mathenge to the region was to restore degraded drylands. The species was seen as an ideal afforestation species because it was extremely drought resistant, its deep roots helping it thrive in harsh, arid environments. The tree was also heralded for its livelihood benefits, growing fast enough to be a reliable source of fuelwood even with constant cutting, and its seed pods providing constant fodder for grazing animals.
The history behind the introduction and spread of P. juliflora in East Africa is mostly uncertain. The first known introduction for restoration purposes was in 1973 at a quarry site near the coastal city of Mombasa, according to a study authored by Esther Mwangi, team leader of the Nairobi hub of the Center for International Forestry Research (CIFOR). The aim was to breathe life into a completely denuded landscape.
In the early 1980s, P. juliflora was introduced through plantations to arid areas in inland Kenya, with the intent to safeguard existing natural vegetation from overexploitation as a result of increasing population pressures.
“If you went to Baringo, Tana River and Turkana in the 1990s, the land was initially very bare with a lot of wind erosion and sunshine. There was no shade,” says Clement Ngoriareng, head of dryland forestry at the Kenya Forest Service, which oversees the management of all forested land in the country.
Mathenge colonized Kenya’s drylands very quickly during periods of El Niño rains, as high temperatures and humidity favored the plant. Immediately after the rains, there was an outcry from the communities. “It restored the landscape but also displaced native vegetation and people,” Ngoriareng says.
A study by the National Environment Management Authority (NEMA) and Egerton University, in Kenya’s Nakuru county, found that affected communities in the district of Marigat had sought government compensation for introducing what they termed a “dryland demon” — demonic in the sense that it inflicted injuries on both people and livestock, while blocking paths where it formed canopies.
Ngoriareng says production of charcoal from the mathenge tree is the best way to curb the spread of the species. However, he cautions that residents must avoid harvesting other plants like acacia for charcoal production, since they do not regenerate as fast as mathenge.
Money from trees
Using charcoal production to both curb the spread of the prolifically invasive plant and reduce demand on native species is consistently described as a positive development by proponents.
In purely economic terms, the opportunity is significant. According to a recent study by the Environment and Forestry Ministry, if all the mathenge trees in the country were turned into charcoal, they would yield 30 billion Kenyan shillings ($295 million) worth of the fuel.
In 2009, the environment ministry published new charcoal rules that legalized the business as long as producers formed groups or charcoal associations. County governments are currently exploring the use of self-regulating industry associations to tackle the mathenge problem. “If we can form associations, this is a nice way of tracking production to ensure people only use Prosopis,” Ngoriareng says.
The Forest Action Network (FAN), an environmental conservation group, focuses on mobilizing community members to adopt mathenge trees to produce charcoal sustainably from the tree.
Dominic Walubengo, the group’s executive director, says he’s optimistic about restoring native species to the landscape within 30 years. The FAN says the best way to accomplish this is to establish groups of charcoal-burning operations and offer capacity for them to produce the commodity in a sustainable manner.
“If special areas for growing the tree are zoned, it is possible to make charcoal from this tree on a sustainable basis,” Walubengo says.
Plant of last resort
Residents describe mixed feelings about whether to keep the mathenge tree or try to eradicate it. On one hand, locals claim not to want mathenge and are concerned about its impact on their farms, animals and water sources. On the other hand, much of the land in the area is not productive enough to generate a sustainable livelihood. They describe turning to a mathenge-based livelihood out of desperation rather than opportunity.
Patrick Akuta lives in Lokangai. The 48-year-old father of 16 is a livestock farmer by profession and a village elder. His homestead is dotted with huts belonging to his three wives. His wives and some of his children shelter under a mathenge tree from the unforgiving sun as the temperature reaches 40 degrees Celsius (104 degrees Fahrenheit). He says he planted mathenge in 1983, more than three decades ago, but thinks the outcome is bittersweet.
“It has its advantages. We cut trees to build houses. We also have contracts to supply wood to the [Kakuma] refugee camp,” he says. Despite its importance, he describes mathenge as a nuisance and laments the impact the tree has had on his ability to maintain his livestock herds.
Athuru Yakai lives in Napeteziro village. She’s a neighbor to Esther Aboi and a charcoal dealer too. Yakai belongs to an association of about 25 to 30 women spread out across several villages in the area. She burns charcoal on a small scale, which she sells to support her family of five children. They readily burn mathenge because the other trees are needed to feed their goats.
Yakai’s charcoal silos are almost full. Five sizeable parts of mathenge tree yield two sacks of charcoal that weigh 50 kilograms (110 pounds) each. To burn the wood, artisanal producers like Yakai dig a pit in the ground and arrange the pieces of wood inside the hole, light a fire, and cover the pile with soil. The traditional kiln is then left to burn, eventually producing charcoal. Yakai sells each sack for between 300 and 500 shillings, ($3 and $5), depending on the season, to traders from nearby Lodwar.
Natele Nyakayi, a resident of Turkwel, says the government should take action. “We want the government to eradicate this tree. We are ready to plant safer trees,” she says, adding that with the mathenge trees gone, they will be able to plant fruit trees.
James Ayemu is the chairman of the Lokangai Charcoal Association, which has 63 people who use mathenge to make charcoal, poles for building, and also fuelwood for cooking at the refugee camps. He says the group is keen to plant indigenous trees in place of mathenge, in the hope that this will boost restoration efforts. “When we cut mathenge tree, we want to replace it with indigenous trees,” he says, adding that they are waiting for the Environment and Forestry Ministry to send them seedlings.
Moratorium on mathenge cutting
Despite the proposals for harvesting mathenge, there is a dilemma. On Feb. 24, 2017, the government of Kenya declared a moratorium on logging in public forests, which includes areas colonized by mathenge.
The ban affects logging in county, national and community forests owned communally. “There is no leeway,” Ngoriareng says. The government is yet to make a decision about how the policy should apply to mathenge-infested areas.
Ngoriareng describes the moratorium as having drastically reduced charcoal production. Since the start of the ban, he says, there has been a massive drop in production, save for local consumption. This means families that used to gain an income from charcoal production now have less of an incentive to control the spread of mathenge.
In the meantime, the unrelenting and aggressive mathenge hasn’t slowed its expansion