Conserving useful plants with local communities in Kenya
In November 2013 we travelled to Nyamira and Siaya in western Kenya to visit communities supported by the UPP. Both regions have hot and relatively wet climates with two short rain seasons a year characterised by sudden downpours of powerful water droplets which pummel the dry earth. Of the two, Nyamira is wetter, more tropical, and hillier with a larger population pressure.
With high population densities, much of the land is used to cultivate crops, such as corn, millet and tea. A patchwork landscape is produced together with fast-growing, exotic species which are used for timber or firewood. Eucalyptus species and Grevillea robusta (Silky Oak) were introduced from Australia in the early 20th century by British rulers to provide fuelwood for the Kenya to Uganda railway and are still favoured because they provide a quick and reliable source of income.
Exotic species and their negative affects
In western Kenya, water scarcity, seasonal flooding and erosion combine to cause crops to fail and housing to be damaged. These problems can in part be attributed to and exacerbated by exotic species. For example, the roots of commonly planted Eucalyptus species run deep into the soil and suck up huge amounts of water, and when grown en masse they lower water tables and alter water systems causing streams to dry up and increasing water scarcity problems.
But that is not all - if not managed well, understory, herbaceous species may struggle. Either the towering trees block out light necessary for photosynthesis or chemicals produced by the trees’ leaves and bark suppress their growth – what’s called the 'allelopathic effect'. Reduced ground cover allows more water to flow through the system, increasing water runoff which damages soils causing heavy erosion along riverbanks and in floodplains, quite literally, taking the ground from under peoples’ feet.
Local, less damaging alternatives could therefore provide economic and environmental benefits. This photo shows the impact of riverside erosion on a local road.
Hunting for alternatives
Through the UPP, initial community workshops were carried out by project partners to identify local indigenous species used for wood and other products, such as food and medicines. During our visit we were shown
- the tasty black fruit of Vitex payos, called Mfudo
- the jam, wine and juice of Dovyalis abyssinica
- the many uses of Tamarindus indica, used as an ingredient in food and a fermented drink
- the roots of Carissa spinarum, which has been shown to contain an ingredient, carissin, which could help fight cancer
Project partners explained how they also promote species which have uses elsewhere in Kenya, which are unknown locally. We were shown one, Melia volkensii, being propagated in community nurseries and planted in an experimental woodlot in Siaya. This fast-growing Kenyan species is championed in the farmer communities in drier Tharaka because of its value as a timber tree to produce high value furniture.
The experimental woodlot demonstrates to locals the similarities of Eucalyptus species, Melia volkensii and two local species, Markhamia lutea and Maesopsis eminii. M. lutea is particularly exciting because it has similar timber uses to M. volkensii and Eucalyptus species whilst also providing a valuable service in soil conservation and erosion control. It is hoped these alternatives will provide similar economic benefits to the communities and be less damaging to the environment.
Plants that heal
In some communities elders are the last vestiges of knowledge of traditional uses of plants. At the moment this knowledge is not being passed on to the next generation and so may get lost. This would be a significant cultural loss to the Kenyan people and could have global implications as a loss of a possible source of knowledge for medicines. Imagine losing the knowledge of the use of Willow plant parts for medical problems, which stretches back to the Ebers papyrus (c 1,500 BC), before the discovery of the active ingredient of Aspirin.
One of the priority medicinal plant species the Nyamira community has chosen to grow is Prunus africana. The timber is strong and can be used in heavy construction and to make other wood products like tools and poles. However, the bark is where the magic is. An extract called pygeum is harvested and used as an effective treatment for many illnesses, including malaria, body and stomach pain, diabetes, kidney disorders, wounds and, most notably, for prostate disorders.
So, P. africana has some obvious economic potential, but the move to grow it is a savvy conservation choice too. Across Africa it is overharvested from the wild for its medicinal uses. So much so that it is now classified as Vulnerable by the International Union for Conservation of Nature (IUCN) and listed on the Convention on International Trade in Endangered Species (CITES) appendix II. The latter makes it illegal to trade without export permits which prove that the harvest did not damage wild populations. Therefore, sustainable cultivation of this tree could help replace wild harvesting, tap into local and global markets and provide a refuge for species survival on peoples’ land.
An alternative future
The UPP aims to promote the conservation and sustainable use of indigenous plants to provide economic and environmental benefits to local communities. In Kenya, we will continue to invest in indigenous species by collecting and conserving their seeds in country and duplicating them at the Millennium Seed Bank in the UK. We will also continue to support community nurseries to grow indigenous species and to provide them to the wider population. Training programmes will continue to teach the wider population how to grow and use these indigenous plants to cause a shift in land management practices to a more conservation orientated approach.
Working with Partners
Our work would not be possible without the dedication of our collaborators and the enthusiasm of the communities in Kenya. We’d like to pay special thanks to Mr William Omondi, country project coordinator and project leader in Siaya, from the Kenya Forestry Research Institute (KEFRI); and Dr. Desterio Nyamongo, project leader in Nyamira, from the Kenya Agricultural Research Institute (KARI), for introducing us to the communities and providing invaluable information about the local ecology, people, customs and politics along the way.
- Alex -