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Trees outside forests: Kenya

James Legilisho-Kiyiapi
Department of Forestry, Moï University, Eldoret, Kenya

Photo 53. Microreforestation with Eucalyptus. (© Faidutti/FAO)


Kenya covers an area of 582 600 km2, including some 10 700 km2 of lakes. One quarter of its population of 28 million are urban dwellers. Forested areas, comprising forest reserves, national parks and sanctuaries are all state-owned and represent less than three percent of the territory. Other woodlands, including woody savannah (bushlands) and forest plantations, cover some 27 percent of the national territory, with agricultural holdings, ranchlands, human settlements and urban areas accounting for a further 16 percent.

Kenya's growing population is exerting considerable pressure on natural resources. As forest resources dwindle with the expansion of agriculture onto forest land, forests will no longer be able to meet the rising demand for wood and non-wood products. This will drive the demand for Trees outside forests and social forestry will become the keystone of tree resources, as an assessment of the woody biomass of the Nakuru and Nyadarua districts clearly indicated.


Forest land is by Kenyan law a designated and legally gazetted forest estate governed by the provisions of the Forest Act. All other land comes under the regulations and usages of either customary law (e.g. communally owned forests), or private tenure regimes (e.g. privately owned forests).

The Kenyan concept of Trees outside forests thus exists within a broad context of land tenure systems comprising all tree resources and land lying outside gazetted or protected forests. Included are woodlands, pastoral systems, agroforestry (the recognized Kenyan designation is social forestry), scattered trees, hedges, and the like. Trees may occur naturally or they may have been planted, and there are no conceptual limits on density or area.

Patterns and extent of change

There is a growing trend in Kenya towards expansion of tree cover and species diversification in intensive farming systems which include trees. As natural formations shrink, are destroyed, or become less accessible, social forestry becomes increasingly important.

Forest plantations, in decline because the rate of replanting has failed to offset the rate of felling, are giving way to grassland. At the same time, farms and settlements are encroaching upon remnants of indigenous forests at an annual rate of 5 000 ha and upon woodlands at a rate of 55 000 ha/yr, with bushland dwindling as well. As timber resources from forest estates decline, wood supply will increasingly come from farmlands and remnant natural woodlands.

There are three distinct agro-ecological, zonal classifications in Kenya. The first two, termed high-potential and medium-potential, correspond to the humid and semi-humid zones. Trees are scattered throughout these two zones on small wooded plots, or dedicated plantations such as eucalyptus grown for fuelwood. The third, low-potential, category consists of the arid and semi-arid zones in which silvopastoral systems predominate.

Early in the 1930-1940s, the high-potential zones still had a fair amount of plant cover and natural forest, but much of the area was then cleared in the process of agricultural expansion. To offset this loss, farmers were offered incentives during the 1970-1980s for extensive tree-planting on farms, with secure land tenure as a pre-condition. The social and economic benefits of this are felt today in the form of income and product diversification which acts as a safety-net to buffer the risk of hardship and destitution. In the low-potential zones where land tenure is less secure, there are two major trends. Tree resources are being depleted in areas of rapid agricultural expansion, but degradation is less severe where traditional land-use systems are still firmly entrenched.

The Kenya Forestry Master Plan (KFMP) stressed the on-farm contribution of trees, which provide wood and poles for construction, fence posts, fuelwood and charcoal, not to mention fruit, fodder, medicines, gums and resin, all for home consumption and/or sale. A study demonstrated that on-farm income from tree crops amounted to 51 percent in the high-potential zones, 40 percent in the medium-potential zones and 18 percent in the low-potential zones (Njenga, et al, 1999). Honey from the Transmara forest region can bring in some US$ 715/yr, in a place where the mean per capita annual income is estimated at US$ 370 (World Bank, 1992).

In any case, the value of all these products would be greatly enhanced if marketing and distribution circuits were designed for profit-sharing. A long chain of middlemen in the wood and charcoal sector, for example, works to the detriment of the grower. By the time a bag of charcoal or wood reaches the final consumer the mark-up can be as high as 150 percent. The same is true for apiculture, where it is often hard for the farmer to market his product for lack of access to outlets. These disfunctional aspects burden the market for off-forest tree resources, hampering official recognition of their contribution to the national economy and allocation of budgetary allocations.

These resources are found mainly in medium-potential woodlands, low-potential bushlands or savanna, and on farms. The mean annual productivity of woody biomass in woodlands is 16m3. In 1995, farms produced 7.4 million m3 of woody biomass, representing 65 percent of the wood production in the high- and medium-potential zones. Assuming a steady growth rate for tree-planting, the figures would rise to 17.8 million m2 and 80 percent by the year 2020 (see Annex 3). The percentage distribution of woody biomass from Trees outside forests is as follows: 20 percent for wood, 7 percent for poles and 73 percent for fuelwood (Holmgren, et al, 1994). In low-potential zones the resource provides forage for livestock.

The most significant role of on-farm trees is environmental. Trees stabilize soil and check erosion in highland areas. A rainforest microclimate has been created by agroforestry areas on Mount Kenya and in western Kenya. Tree/agriculture mixed cropping on farmland offers a habitat for the conservation of increasingly endangered indigenous tree species such as Prunus africanus. Another increasingly popular practice is the domestication of natural forest species and their introduction on farms and in urban areas. In the Masai and Turkana communities, the bond between people and their environment has produced a conservation ethic for this resource, underpinned by a social and cultural value system.

Institutional and management aspects

The Forest Act applies only to the legally gazetted forest estate, with no mention of other tree formations such as those growing outside forests. New legislation was formulated to bridge this gap and broaden the framework of tree resource management. The Chief Authority Act, the Agriculture Act and the Water Act serve as points of reference for trees outside forests but their thrust is more punitive than motivational. The legislation is currently undergoing reform in light of the renewed interest in natural resources and the innovation of people's participation. Recent legislation such as the 1996 Physical Planning Act and the 1999 Environmental Management and Coordination Act provide a legal framework for participatory land management at local and regional levels, and are bound to influence future institutional provisions concerning off-forest tree resources.

The Department of Forestry, backed by cooperation agencies and working in liaison with NGOs, has implementated action to promote Trees outside forests. Illustrative of this process are the Transmara Forest and Resource Management Project, the Regional Land Management Unit (RELMA) which focusses on how trees are used on farms and in private and communal natural woodlands, and the Forest Action Network (FAN) which is actively involved in the conservation of community forests and tree resources. These actions are often fragmentary, and coordination among them and with research, extension and the farmers can be problematic.

Concerning research, on-farm species trials are being run by the International Council for Research on Agroforestry (ICRAF) in collaboration with the Kenya Forestry Research Institute (KEFRI). Ethnobotanical work by the National Museums of Kenya is also underway on these resources.

Farmers draw upon traditional tree improvement, planting and maintenance skills for Trees outside forests. They apply traditional resource management practices to communal areas. Tree resources and land are all collectively owned in the silvopastoral systems, where the accent is on the management of natural tree formations.

Assessment and planning

National forest inventories have not been conducted on a regular basis. The most recent and detailed assessment, dating from 1993, covered forest resources and selected community forests. Although virtually no specific inventories preceded the implementation of action to promote Trees outside forests, surveys and assessments had been done in target intervention areas.

Photo 54. Single trees scattered throughout fields. (© FAO)

Prior to the implementation of the Nakuru-Nyandarua social forestry project in 1991, the Ministry of Natural Resources and Environment conducted a baseline woody biomass survey funded by FINNIDA on gazetted forest and farms, which was replicated in 1993 and in 1998 (Pukkhala, 1991, Höyhtyä et al, 1998). A large-scale woody biomass survey was conducted in 1991-92 on approximately 10 million ha as part of the KFMP development process. A systematic grid of low-altitude aerial photos was combined with field measurements to produce a sub-sample. The national wood supply was estimated from variables such as species identification, volume, density and potential wood uses (Holmgren, et al., 1994). Other local assessments included a 1996 GTZ-funded forest/woodland survey in the district of Transmara which combined satellite imagery, aerial photographs and line transect-fixed radius plot methods, and an on-farm tree inventory by KEFRI in Tharada-Nithi (Kigomo, 1997, Kiyiapi, 1999). An ongoing assessment of trees in semi-arid zones based on the same methodology as the Transmara survey is expected to report its findings in 2001. ICRAF has also begun on-farm and tree nursery surveys in western and central Kenya.

The KFMP plans to make the forest sector an integral part of both the National Environmental Action Plan (NEAP) and the National Development Plan. With the new policies and legal provisions on decentralization, land-use planning will increasingly become a local responsibility, a likely boost for off-forest trees. Their role in relieving pressure on indigenous forests is significant in the light of global agreements to which Kenya is a signatory, primarily those relating to forests, biodiversity and climate change.

Assessment of woody biomass in Nakuru and Nyadarua

The Nakuru-Nyandarua Farm Forestry Project (1990-95) was started with the goal of raising trees for the farmers' benefit and easing pressure on existing natural forests.

The first stage of this project consisted of a 1991 baseline woody biomass survey. While satellite imagery was useful in broad-level vegetation classification of indigenous forests and plantations because of their size, it was not very helpful for detailed assessments of trees at the farm level. A second stage of the survey launched in 1993 combined aerial photos and ground surveys to establish a more realistic tree cover baseline against which to judge the success of the project. Aerial photographs were taken at one-kilometre intervals at the 1:10 000 scale. Each photo covered a ground area of 2.3 km x 2.3 km. Subsequent enlargement at a scale of 1:2500 produced a 23 cm x 23 cm print representing 575 m x 575 m on the ground.

The photo-interpretation method used delineated the boundaries of the farms closest to the centre of each 1:2500 enlargement, i.e., the farms selected for photo-interpretation. Tree species and sizes could not be distinguished due to the distorting effects of shade, differences in tree form and size and the difficulty of recognizing boundaries, but homesteads, border trees, grazing areas, farm size, kitchen gardens and woodlots could be classified. About 20 percent of these farms were then selected for detailed field measurements (38 in Nakuru and 24 in Nyandarua). Each tree on the farm was assessed and, where necessary, sub-sampling was applied to woodlots and boundary trees. The parameters assessed were tree location, species and origin, and tree volume determined from established allometric relationships. A 1998 assessment based on the same methodology revealed a significant increase in woody biomass.

The surveys showed an increase in per hectare productivity. The productivity of trees on farms rose from 25 m3 in 1993 to 56.9 m3 in 1998, an increase of 128 percent, with an overall boost in productivity of 9.6 m3 in 1993 to 19.9 m3 in 1998 for the entire zone, i.e., up 107 percent for that period. In 1993 as in 1998, 70 percent of the tree diameters were under 5 cm, making the trees too small to harvest. The volume of usable wood on each farm was 17.l m3 in 1998 compared to a figure of 7.5 m3 in 1993. The results revealed both the positive impact of the project and the usefulness and effectiveness of the inventory methodology, which is now being applied in other districts.

From the standpoint of methodology, satellite imagery is primarily relevant for broad classification of large-scale plant formations. The results from the interpretation of aerial photos compared with those obtained from field surveys suggest that aerial photos are useful at the stage of defining the sample, but are not very reliable for estimating tree biomass on farms. There was no relationship between the values obtained from photo-interpretation and actual field measurements, making extrapolation of the data to other aerial photographs impossible. And the high cost of aerial photography may well penalize ground measurements, bearing in mind that their comparative advantages depend on assessment parameters that must be very strictly defined prior to the establishment of the sampling-plan.

Trees outside forests comprise a number of highly complex systems, so further study is needed. Assessment methodologies which combine remote sensing techniques with ground verification offer promise, but much remains to be done before generalized assessment designs can be developed. And assessment should draw much more heavily on participatory methodologies.


Population growth is exerting considerable pressure on Kenya's natural resources. The constant decline of forest resources coupled with new developments in land tenure systems further the exploitation of remnant natural woodlands, hence the renewed interest in trees growing on farmland. The future of forests and tree resources basically depends on the growth and management of woody biomass which lies outside Kenya's forest estates.

The national development strategy for Trees outside forests stipulates sustainable management of natural forests and woodlands in the semi-arid and arid zones, as well as tree-planting on farms and in settlements. Recent legislation and the promulgation of the new forest law will facilitate a multisectorial and participatory approach to environmental protection and natural resource management, including the management of trees growing outside the forest Sustainable land-use planning, effective organization of this tree resource and co-ordinated land distribution can become a reality. But users, including farmers and herders, must partake in the decision-making and negotiation stages of the process to sageguard Trees outside forests.


Holmgren, P., Masakha, E.J. and Sjoholm, H. 1994. Not all African Land is Being Degraded: A Recent Survey of Trees on Farms in Kenya Reveals Rapidly Increasing Forest Resources. Ambio 23(7): 390-395.

Höyhtyä, T., Kariuki, M., Njuguna, P. and Wamichwe, K. M. 1998. Nakuru-Nyandarua Districts Woody Biomass Survey. FINNIDA Project Terminal Report , Ministry of Environment and Natural Resources, Department of Forestry, Nairobi

IUCN. (International Union for the Conservation of Nature) 1996. Forest Cover and Forest Reserves in Kenya: Policy and Practise. Regional Office for East Africa, Nairobi.

JICA. 1992. The Study on the National Water Plan. Sectorial Report. Environmental Conservation. Main Report vol. I. Water Resources Development and Use Towards 2020. Ministry of Development and Water Resources, Nairobi.

Kenya Forestry Master Plan. 1994. Ministry of Environment and Natural Resources, Nairobi.

Kiyiapi, J. L., Ochieng, E. A., and Otieno-Odek, J. 1996. Forest/Tree Resources Survey in Transmara: Technical Report. Projet GTZ/TDP. Transmara, Kenya.

Ministry of Environment and Natural Resources. 1994. Kenya National Environment Action Plan. Nairobi.

Njenga, A., Wamicha, W.N. and van Eckert, M. 1999. Role of Trees in Small Holder Farming Systems of Kenya: Results from High, Medium and Low Potential areas in Kenya. Paper Presented at International Workshop Off-Forest Tree Resources of Africa, 12-16 July. Arusha, Tanzania.

Pukkhala, T. 1991. Wood Biomass Baseline Survey. Nakuru and Nyandarua Intensified Forestry Extension Project. Technical Report II. Department of Forests, Nairobi.

Pukkhala, T. and Niemi, T. 1993. Quantity of trees on small farms in Nakuru and Nyadarua. Nakuru-Nyandarua Intensified Forestry Extension Project. Technical Report V. Department of Forestry, Nairobi.

Wass, P. 1995. Kenya's Indigenous Forests: Status, Management and Conservation. IUCN. Gland, Switzerland. Ed. Cambridge, U.K.

Annex: Woody biomass trends and potentials

Table 13 indicates a downward trend for indigenous forest, woodlands, savanna and forest plantations, whereas Table 14 shows an upward trend for farms and settlements.

Table 13: Wood resources: current trends and prospects (`000 ha)

Type of formation









Indigenous forest

1 295

1 270

1 245

1 220

1 195

1 170

Woodlands and savanna

37 425

37 150

36 875

36 600

36 325

36 050

Farmlands and setlements

9 720

10 020

10 320

10 620

10 920

11 220

Forest plantation








48 588

48 574

48 558

48 547

48 533

48 518

Source: Kenya Forestry Master Plan (1994).

Table 14: National woody biomass inventory, current trends and prospects (productivity in m3/ha.

Type of formation









Indigenous forest







Woodlands and savanna







Farmlands and setlements







Forest plantations







Source: Kenya Forestry Master Plan, 1994.
Note: In line with the concepts outlined in this paper, Trees outside forests are those found on woodlands, savannah, farmlands and settlements.

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