Fever Tree

Fever tree (Acacia xanthophloea) is a fast-growing, medium-size tree (reaching 15 to 25 m in height) with smooth, yellow-green bark. Thorns up to 7 cm long grow on the trunk and become denser in the spreading branches (Figure 9). Fever tree can be found throughout Africa, most commonly in swampy, low-lying areas. The tree’s common name indicates its association with malarial fever; this is because mosquitoes that transmit malaria prefer such swampy areas for breeding. Fever tree can grow up to 2100 m above sea level and can tolerate moderate frost (Lemmens, 2006).

Wood from the fever tree is used for construction and carpentry, being durable with attractive brown to reddish coloring. The wood cracks easily, unless seasoned by drying. The wood is also susceptible to termites and wood borers (Triozastus baghaasi), an important consideration when using the wood for construction and/or carpentry. Fever trees are also used for fuel, with the wood either burned directly as firewood or used to produce high quality charcoal (Lemmens, 2006). Charcoal is a key energy resource, and charcoal production helps many people generate income in parts of the tropics. If charcoal production is to be environmentally and economically sustainable, communities require good post-harvest management strategies and environmental policies that include all stakeholders (Chidumayo and Gumbo, 2013). An example of collaborative and sustainable efforts is that of Tanzania’s Kilosa district forest management and charcoal production methods. Politicians, community members, and the Tanzania Forest Conservation Group (a Tanzanian NGO) worked together to determine harvest and production practices that would conserve forest ecology as well as provide income in the long term. These practices include not returning to a harvested section for 24 years; leaving at least 60 cm of the trunks to remain as stumps after harvest; and using basic earth kilns to produce charcoal. Detailed crop management for charcoal production, and multiple processing technologies, can be found in the Sustainable Tree Management for Charcoal Production Acacia pocketbook prepared for PISCES by Practical Action Consulting East Africa (Oduor et al., 2012).

The fever tree is useful for reasons beyond its wood. The tree’s yellow, fragrant flowers provide forage for bees, while the feathery leaves can be fed to livestock. Fever tree bark is harvested for medicinal applications in East Africa. Livestock may also remove the outer bark of the tree (Figure 10). Fortunately the tree has high tolerance for bark damage, and often recovers from human or animal destruction (Lemmens 2006). The roots of fever tree form symbiotic relationships with microorganisms, which fix nitrogen and enrich the soil.

Soaking seeds for 24 hours before seeding in the nursery may help speed up germination. Once seedlings have at least two leaves, you can transplant them to larger vessels that contain local potting mixture (this may need to be supplemented with compost or aged manure if it lacks nutrients). Transplant trees into the field at the onset of the rainy season for good establishment. If growing the trees for charcoal production, space them a minimum of 2 m apart (both in row and between rows). 

Because of the thorns, protective clothing is recommended when harvesting any plant material from a fever tree (timber, seeds, etc.). Stumps will resprout multiple branches; leave up to four new dominant branches for maximum production. The thorns are a definite disadvantage. Many non-thorny tree species can be used instead for fuel production, including leucaena (Leucaena leucocephala), gumbo limbo (Bursera simaruba), calliandra (Calliandra calothyrus), Madre de Cacao (Gliricidia sepium), Erythrina spp., Inga spp., Grevillea spp., Albizia spp. and Siamese senna (Senna siamea).

References

Chidumayo, E.N., and D.J. Gumbo. 2013. The environmental impacts of charcoal production in tropical ecosystems of the world: A synthesis. Energy for Sustainable Development 17(2): 86-94.

Lemmens, R.H.M.J. 2006. Acacia xanthophloea Benth. [Internet] Record from PROTA4U. Louppe, D., A.A. Oteng-Amoako, & M. Brink (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 28 March, 2019.

Oduor, N.M., W. Ngugi, and T. wa Gathui. 2012. Sustainable Tree Management for Charcoal Production: Acacia Species in Kenya. Acacia Pocketbook. Bloomfield, E., K. Welford, and H. Wanjiru (Editors). Practical Action Consulting East Africa.