Kakamega Forest reserve is the only rainforest in Kenya and the most eastern extension of the vast Congo forest. It rains about 250-300 days a year. The rainfall (average 1700-2800 mm. p.a.) is increasing as the temperature rises. Most of the original forest has gone. There are three parts, of which the lower area, Kakamega Forest National Reserve, covers about 22,500 ha. (55,000 acres). To protect the forest, former President Moi ordered tea to be planted around much of the forest, which resulted in more than 1000 ha. of primary forest being cut down.
Tea protection zone around the forest
One hundred years ago Kakamega rainforest covered around 250,000 ha. (635,000 acres). Two other adjacent forest blocks (North and South Nandi forest) are at higher altitude and have a different plant diversity. The three blocks today cover about 60,000 ha. Only about 15,000 ha. of Kakamega Forest is original rainforest. The big megafauna (buffalo, leopard etc.) have all gone but there are seven species of primates and other small mammals, including unusual species like pottos and flying squirrels.
The forest today comprises both natural forest, plantations of exotic species like cypress and eucalyptus or, even worse, introduced invasive species like the guava (Psidium guajava) from tropical America or a tall tree known as Bishop wood (Bischofia javanica) from Java. These two latter species are dissimilar. Guava is a small tree (4m) with delicious fruit and extremely hard wood. Bishop Wood is a very tall, fast-growing straight tree (>40m) with low quality soft wood. Many of the native trees in the forest are so tall that they can be very difficult to identify but one can sometimes identify them based on the bark alone.
The Kenya Forest service has allocated a plot of land of indeterminate size to Plants for Life near Rondo Retreat. We received initial funding from Nicholsons of Oxford.
The plot comprised 80% guava, 15% Bishop Wood with some eucalyptus and 5% native vegetation. Our aim is to remove these non-native species and replace them with indigenous vegetation. The replacements will come from four sources, natural regrowth, tree nurseries, the cypress plantations (where indigenous ‘wildings’ can be dug up and replanted) or by direct seeding (fruiting time is late February/ March). Since July 2024, we have planted more than 2000 seedlings of over 300 species of local trees and shrubs and we aim to reach 1000 recorded plant species.
In addition to invasive plant species (the roads are lined with at least a dozen plant species from every continent), the forest is under threat from two other sources. First, the human population pressure is immense. Kakamega county is one of the most densely populated rural counties in Kenya with over 620 persons per square km. Electricity is uncommon in surrounding villages so the population relies on collecting ‘dead’ wood from the forest for cooking. Every day hundreds of women carry heavy loads (up to 30kg) of firewood on their heads. They walk from the forest for several hours to nearby villages. The problem is that it is easy ring-bark a tree: in a year or so the trees are prematurely killed.
The second challenge is uncontrolled livestock grazing in the forest. Cattle and goats wander about in the forest trampling on and eating tree seedlings. The Kenya Forest Service does not allow wire fences so we have constructed post-and-rail fencing using guava wood to keep out the cattle.
Our next problem has been teaching our team how to identify and distinguish young plants, which might be ‘weeds’, invasive seedlings or rare trees. The local language is ki-Luhya, which comprises at least 13 dialects that are often so distant as to be mutually incomprehensible. Common trees have names in the local ki-Luhya dialect, which might be very different from the names used by other sub-tribes. The rare trees often do not have local names, nor in English or Swahili, so we have to rely on scientific names, which is not easy when we have tree species such as Bequaertiodendron oblanceolatum, which has recently been renamed Englerophytum oblanceolatum. In a few years, they will probably drop the names of 19th Century colonial botanists1 from scientific nomenclature, and they will have to learn new names.
Our staff not only have to distinguish indigenous seedlings from exotic or invasive seedlings but they also need to get the names of hundreds of local plant species into their heads. This goes against the trend in Africa (and probably the rest of the world) where loss of indigenous knowledge leads to loss of indigenous biodiversity. The good news is that there is increasing interest in developing ways of awarding biodiversity credits for maintaining or restoring the diversity of native species, especially rare and endemic ones.
1The tree in question was originally named in the Congo by a Belgian (Joseph Bequaert) and then renamed after the German (Heinrich Engler) who probably found it elsewhere a bit earlier.
The biodiversity in a rainforest is high and of course, it includes more than just trees. It covers mammals, birds, fungi, ferns, reptiles and many other forms of life. The next antibiotic or anti-Alzheimers drug may well come from some fungus or snake venom, which is an added reason for conserving biodiversity.
Kakamega forest has over 360 species of birds and nearly 500 species of butterflies, which much prefer the natural forest. It is also home to 33 species of snakes, only half of which are venomous. Locals, like most humans, tend to fear snakes and therefore kill them whenever they see them. Our team spends a great deal of time and effort getting locals to respect them, once we have convinced our own staff not to kill them. We have had three close encounters since we started in July 2024 with less ‘popular’ snakes, two of which are the most beautiful snakes in Africa. We saw a Gaboon viper was hiding in a pile of cut guava wood before it slithered away at great speed (by adder standards) into the forest. They tend to be territorial so it is likely to return. My co-collector walked into a black mamba as it was sloughing its skin. After a loud and grumpy hiss, it fled (so did the collector). We also disturbed a Jameson’s Mamba sunbathing in a tree two metres above our heads while we were looking for seeds and it also shot away in the trees like greased lightning. They hear (or feel) us far sooner than we see them. Snakes are shy, shun human contact and are only aggressive when trapped e.g. in houses. Vipers are ambush predators, relying on camouflage and they tend not to move. But like most of us they do not appreciate being trodden on. We spend a lot of time deep in the forest where there are no paths but the ordinary visitor is highly unlikely to encounter a snake. I have never heard of anyone in Kenya being bitten by the placid Gaboon viper2 but unusually we had one fatality last year from a Rhinoceros viper.
2 They are the largest vipers in the world and can grow to 1.8m (6ft) and have the longest fangs of any venomous snake. The highly complex venom not treatable by normal polyvalent antivenene.
Guava seedlings pop up at a density of about 100 per sq.m. and even small ones are nearly impossible to pull out by hand. That is a million seedlings per hectare. We are not allowed to use glyphosate or other noxious (but effective) herbicides so some ingenious ideas are needed.
It is sad is that the tourists from overseas rarely visit highly populated Western Kenya. They want to see the big game of the savannah regions. A few are birders but forests are low priority when in fact they are fascinating and intriguing for the real naturalist.
Our project has only just started but it promises to be an exciting one. If we can attract more funding, the area we could restore would be far greater. Trees grow faster here than anywhere else in East Africa. We have already found two tree species new to science and a further three that have hardly (or never) been recorded before in Kenya. The biggest problem on site is how to prevent guava regrowth.
The initial trial programme
- To remove as much of the guava and other invasive species in the area allocated within one year (July 2024-June 2025).
- To collect and plant indigenous trees and other plant material on site
- To maximize plant and other biodiversity
- To record planted tree and shrub species (from seed, wildings and tree nurseries), their coordinates, survival and phenology (height, dbh and canopy width). Current list is appended.
- To record bird, butterfly and reptile numbers on the site and monitor increase in all visible biodiversity over time and compare with biodiversity in nearby areas of exotic trees and non-indigenous plantations.
- To expand the area only when we have controlled or eradicated invasive species.
- To create a blog recording findings and collect data for eventual publication.
See the full list here: Kakamega Restoration Project Tree Species
Species Planted on the site: OXFORD NICHOLSONS PLANT LIST KENYA 28 FEB 2025
