Kikuyu Escarpment Forest
Kikuyu Escarpment forest lies 30 km north-west of Nairobi, and covers the southern slopes of the Aberdare Escarpment. To the far south, the forest has been greatly fragmented leaving only scattered remnants of indigenous forest. In order to facilitate management, the Kikuyu Escarpment Forest which covers an area of 37,620 ha was divided into six major blocks, each under auspices of a forest officer and several subordinate staff. The blocks are Kereita, Uplands, Kinale, Kamae, Kieni, Raggia and the Kijabe Strip under Kinale and Uplands stations. Kereita Forest Reserve, the focal area for KENVO’s research and conservation interventions, lies to the southeast of the Kikuyu escarpment, largely within the Kijabe Location. On its northern side, it borders some parts of Kinale forest while its southern portion extends to reach the Upland forest. Kereita forest covers an area of 4,720 ha, of which 75 % is indigenous forest, 8 % is exotic forest, the rest being bamboo, shrubland and some herbaceous croplands.
Location: 0°56’S, 36°40’E
Area: 37,600 ha
Altitude: 1,800.2,700 m
Topography: rugged, with many steep-sided valleys containing fast-flowing permanent streams
Rainfall: Mean 1,500 mm per year but varies with location
Geology and soils: Volcanic activities of Mt. Kenya region shaped the existing formations. Numerous series of lava flows have become eroded over the years resulting in the rich volcanic soils. The soils are highly fertile, well-drained with dark-reddish brown coloration
Drainage, stream pattern and hydrology: Most of the rivers and streams in this site such as Gatamaiyu, Bathi, Kiruiru and Nyanduma start from the forests, typically flowing south-easterly before joining up to form part of Athi River left bank tributaries (Nairobi River)
Local Administration: Central Province, largely within Kiambu and Thika Districts (with small sections in Nyandarua and Murangi Districts)
Flora: Mixed bamboo and forest in the higher north-west section makes way for broad-leaved forest, with species of Ocotea sp., Podocarpus latifolius, Macaranga sp., Noxia congesta, Neoboutonia and Strombosia spp. prominent among the trees; tree ferns Cyathea manniana are also conspicuous (Blackett 1994). The Escarpment strip consists of remnant Juniperus forest and overlooks the mountainous floor the Great Rift Valley
Avifauna: This forest is an Important Bird Area (IBA2) with a rich avifauna, characteristic of the central Kenyan highlands (Bennun and Njoroge 1999). Recent research by Nature Kenya and Ornithology (NMK) documented about 138 species of birds in and around the forest, of which 31 are forest specialists and 20 are considered rare. At least 39 of Kenya’s 67 Afrotropical highlands biome species occur here. The forest is home to the globally threatened Abbott’s Starling Cinnyricinclus femoralis where it has been recorded almost the whole year around. Other restricted range species like Jackson francolin and Hunter’s cisticola also occur, as well as a significant number of regionally threatened species including African green ibis, Ayres hawk eagle, Crowned hawk eagle, and Red-chested owlet (Zimmerman et al. 1996)
Mammals: African elephants are occasionally encountered at Kereita when wandering from the main Aberdare forest block. Other mammals found here include Black and White Colobus Monkey, Sykes’s Monkeys forest hogs, small antelopes like duikers, bush-babies, porcupines, and carnivores like mongoose and civets.
Insect-life: Three near-endemic butterflies occur, namely Charaxes nandina, Neptis kikuyuensis and Neptis katama (Larsen 1991)
The Human Factor and Conservation
Local community: The local community is composed largely of small-scale farmers. The climatic conditions and soils can support diverse crops such as green kale, cabbages, potatoes, beans, and maize. Green kale is grown mostly for commercial purposes. Farming is generally mixed with most farmers also keeping livestock such as cattle (dairy production is a major component of households’ income), sheep and poultry. Besides food cash crops such as horticultural fruit and vegetable products, tea is also a major permanent cash crop that is planted near Kereita and Kinale forests
Demographic factors: The average population density of the area (Lari Division) is 195 people per km squared. Populations are most concentrated in areas within 3 km radius from the forest. 1-14 and 60-80 years age classes account for 49 % of the population, while 15-49 years represent 51 %
Socio-economic importance: The forest plays an important role as a catchment area for the many rivers and springs that provide water to the local population (Kuria et al., 1997), as well as supplying a significant portion of water for domestic use in Nairobi (Akotsi et al. 2006). It is also the main source of forest products for the local residents supplying medicinal plants, fuelwood, charcoal, timber, building and fencing poles, grazing ground, wild fruits, manure and important places for traditional practices
Agricultural issues: At the Kikuyu Escarpment Landscape, few farms are sufficient to support domestic requirements and leave the surplus for sustainable income. Consequently, farms are heavily cultivated thus diminishing soil fertility; many are highly eroded. This has resulted to over dependency of inorganic fertilizers to improve agricultural productivity. Development of livestock and crop production is mainly hampered by the lack of land, poor markets, exploitation by middlemen, poor rural infrastructures, over dependency of few types of crops and lack of adequate advice from the relevant authority
Conservation issues: Poverty and ignorance of forest adjacent communities are major conservation problems facing the Kikuyu Escarpment Forest. Majorities of the peri-forest communities of this area are economically unstable. This has a direct impact on the forest because some of the residents diversify their incomes by undertaking unsustainable activities such as timber harvesting, charcoal burning, and encroachment into catchment sites
Urban development: Lari Division, within which Kereita forest occurs, is among the fastest growing areas in the outskirts of Nairobi seeing a relentless mushrooming of shopping centres. As a result, the area is experiencing a number of problems associated with urban development mainly high population, increased unemployment, high crime rates and other anti-social behaviour. The ever-increasing human population and the high level of poverty continue to be major threats to food security and conservation of natural resources, particularly forests.