Kakamega Forest
Geology and soils
The geology of Kakamega Forest Ecosystem can be described by underlying rocks that include basalt, phenolites and ancient gneisses of the Kavirondo and Nyanzian Systems which are associated with gold bearing quartz veins. The rocks form moderately fertile clay-loam soils. Forest cover, with its continuous nutrient recycling activity can maintain itself permanently on these soils.
Topography
The Forest Ecosystem lies in Lake Victoria Basin, about 150 km west of the Great African Rift Valley, from which it is separated by highlands stretching from Cherangani Hills in the North to the Mau Escarpment in the South (KIFCON, 1994). It borders the Kakamega Escarpment to the northeast, falling to lowland of relatively flat topography with altitude ranging between 1,500 and 1,600 m above sea level and up to 2,060 m atop a few scattered forested hills such as Bunyala and Lirhanda.
Hydrology
The Kakamega Forest Ecosystem forms part of the Lake Victoria Basin. It has a good system of rivers which run from the North East to South West. Rivers Nzoia and Yala are the main rivers. River Nandamanywa drains into Isiukhu River, which ultimately drains into Nzoia River, having criss-crossed the forest for the entire length. River Nzoia eventually drains into Lake Victoria. A general hydrological map of the Kakamega Forest Ecosystem is shown in Figure. 2. For most of these rivers, sub-catchment management plans have been developed and some are being implemented. These include Banja, Isiukhu, and Garagoli rivers.
Biodiversity
Due to its former connection to the Guinea– Congolian rain forest system, the Kakamega Forest Ecosystem is home to many species that are related to the Central and West African flora. There are also several endemic
species, i.e. animals and plants that are not found anywhere else in the World. However, it is no longer a primary forest but an old secondary forest, despite small patches in the Central forest areas that have, to all appearances, the attributes of a primary forest (Holstein et al, 2010).
Flora
More than 120 species of trees have been recorded in the Kakamega Forest Ecosytem. More than 70% of all plant species are of minor or major medicinal importance. Some of the conspicuous plants of Kakamega Forest include: Whitlow Root – Solanum sessilistellatum Bitter; Spiny bole – Chaetacme aristata Planch; White thorn – Acacia sp; Spiny – Acanthus – Acanthus pubescence; Afromomum sp, Aneilema johnstonii; Antheroma naudinii; Desmodium repandum; Dissotis speciosa; White flowering Commelina – Comelina albiflora; Wild fig – Ficus thonningi; Gomphocarpus semilunatus; Habenaria malcophylla; Tree Orchid – Tridactyle bicaudata; Impatiens hochstetteri; Lantana – Lantana camara; Klip Dagga – Leonotis nepetifolia; Mussaenda arcuata Poir; Pollia condensata; Tall Woodland Sugarbush – Protea madiensis; Guava – Psidium guanjava; Kakamega Flame – Spathodea campanulata; Nitobe Chrysanthemum Tithonia diversifolia; Kenaf – Hibiscus cannabinus amongst many others (Holstein et al, 2010). The forest is also home to threatened tree species, Elgon teak and Prunus africana which are species of special conservation concern (locally threatened and rare). These species are prone to over exploitation due to their high quality timber and medicinal value. On the other hand, scientific research has indicated the presence of 13 different plant communities each representing a different succession stage. Forest plantations in the forest reserve covering about 3,199 ha comprise of Pinus patula, Pinus eliotii, Cupressus lusitanica, Eucaluptus saligna, Grevillea robusta and Bischofia japonica have been established for productive purpose. Strategic Ecosystem Management Plan 2015 - 2040 9