part of the South Province of the Republic of Cameroon and is subdivided into the Departments
Océan and Ntem. The TCP area covers about 1700 km
which to a large extent coincides with a
concession of the Dutch logging company of Wijma-Douala S.A.R.L. (GWZ).
All roads leading to and within the TCP area are dirt roads. Two governmental roads delimit the
TCP research area, the Kribi-Bipindi-Lolodorf-Ebolowa road in the northwest and the Kribi-
Akom II-Ebolowa road in the south. Within the area three principal roads are present, two of
which having approximately a W-E direction and one a SW-NE direction. In addition many
smaller exploitation roads have been constructed. Accessibility of these, however, is variable as
maintenance is carried out by the logging companies and ceases once their activities are
transferred to other regions. Footpaths connecting villages are found throughout the area.
Transport by boat over the rivers is not possible due to the presence of rapids and waterfalls.
The climate of Southwest Cameroon is equatorial. Although rainfall occurs throughout the year,
two distinct minima and maxima can be distinguished in the annual pattern which are associated
with the N-S movements of the Intertropical Convergence Zone over the area. The humid seasons
extend from September to November and from April to May, whereas the drier seasons extend
from December to March and from June to August. According to the classification system of
Köppen (1936), the climate of the area is classified as humid tropical (Aw). Such a climate has a
mean temperature in the coldest month above 18
°C, an average annual temperature of around
°C with little variation between years, and at least one distinct dry season.
Table 2.1 Summary of climatic data for selected stations in Southwest Cameroon (Olivry, 1986)
Mean annual temperature (
Mean annual relative humidity (%)
Mean annual vapour pressure (mbar)
Mean annual rainfall (mm)
Wind speed below 4 m s
(% of time)
Main wind direction
Kribi n= 45 years; Lolodorf n= 25 years; Ebolowa n= 48 years; n.a. = data not available.
A summary of climatic data of selected stations in the region is presented in Table 2.1. The long
term annual mean temperature decreases from West to East, corresponding with an increase in
altitude (Olivry, 1986).
Long-term averages of monthly rainfall totals of the Kribi, Lolodorf and Ebolowa stations are
presented in Figure 2.2. Due to the geographic position of the TCP research area, the rainfall
pattern in the area is likely to resemble those at Lolodorf and Ebolowa, rather than that at Kribi.
Wind speeds are generally low and the direction is predominantly W-SW throughout the year
(Dolman & Waterloo, 1995).
The duration of bright sunshine has not been measured at any of the weather stations in South
Cameroon. However, the mean daily value of 3.4 h day
observed at the weather station in
Douala is a fair approximation (Dolman & Waterloo, 1995).
The hydrography of Southwest Cameroon is characterized by a high drainage density as a result
of a humid climate and the low permeability of the crystalline rock formations (Franqueville,
1973). The main rivers draining the TCP research area are the Lokoundjé, Tchangué, Kienké,
Moungué, Biwome, Sonkwé and Messambe. Their flow direction is generally NNE-SSW,
following the regional pattern of faulting. Smaller streams have a flow direction essentially
perpendicular to the main rivers, resulting in a drainage pattern that has both dendritic and
Swampy areas are commonly found in the valleys of the smaller rivers. The soils in these areas
remain waterlogged even during dry periods due to a continuous supply of groundwater from the
hill slopes and due to relatively thin valley soils underlain by massive rock of low permeability.
Prior to 1995, hydrological studies have not been carried out at any location within the TCP
research area. Hydrometric stations of the `Centre de Recherches Hydrologiques' of the `Institute
de Recherche Géologique et Minière' (CRH-IRGM) were located in Lolodorf in the Lokoundjé
river (draining the area north of the TCP research area) and in the Kienké river (partly draining
the TCP research area) and the Lobé river (draining the area south of the TCP research area) at
Kribi. However, all stations in South Cameroon have been abandoned since 1987 (pers. comm.
J.C. Ntonga, 1996).
The discharge patterns of the rivers correspond to the seasonal rainfall pattern with maxima in
October and May and minima in August and February (Olivry, 1986). Figure 2.2 shows the
monthly discharges of the Lokoundjé, Kienké and Lobé rivers for the 1953 -1977 period.
The average annual discharge of the Lokoundjé river (at Lolodorf) amounted to 773 mm, whereas
those of the Kienké and Lobé rivers amounted to 1082 mm and 1397 mm, respectively. Rainfall
on the Lokoundjé basin and the Kienké and Lobé basins could be estimated at 1880 mm and 2425
mm, respectively, resulting in runoff coefficients varying between 41% for the Lokoundjé basin
and 45% and 58% for the Kienké and Lobé basins (Olivry, 1986).
Annual evaporation rates obtained with the water balance method varied between 1107 mm for
the Lokoundjé basin and 1345 mm and 1025 mm for the Kienké and Lobé basins (Olivry, 1986).
The electric conductivity of stream water in the TCP research area is extremely low and varies
in the dry season (Dolman & Waterloo, 1995). On the basis
of data collected in one rainy season two EC zones can be discerned, the eastern part of
The Ntem complex is comparable to the Calcium-magnesium complex. The Nyong series
consist of meta-sedimentary rocks which are composed of migmitates, gneiss, quartzites and
amphibolites. In addition, in the Lolodorf region, some small lenses of ferro-magnesian
rocks are found, such as amphibolites, diorites and gabbros, forming discontinuous bands
with a general NE-SW direction.
During the present survey, mainly gneisses of various composition were found, as well as
locally granites, migmatites, amphibolites, diorites and gabbros. Soils developed under a
humid tropical climate on these metamorphic and igneous rocks will be composed of clay
minerals (mainly kaolinite) with quartz sand and iron(hydr)oxides. These soils are acid and
have low nutrient contents.
The overall tectonic direction in the Basement complex is NNE-SSW. Two synclinal zones
and one anticlinal zone can be distinguished in South Cameroon. The first synclinal zone
coincides essentially with the Sanaga valley, the second occupies Cameroon's southern
border and disappears under the coastal basins. The anticlinal structure is composed of the
metamorphic complex of Ntem which forms an extension of the Ebolowa-Ambam granite
zone (Franqueville, 1973). Mineral resources of the geological formations in this part of the
country are not economically exploitable (Franqueville, 1973
The Atlantic coast of Southwest Cameroon is characterized by large swampy areas in the
Douala basin while southwards a rocky coastline is present. Going eastward, the landscape
changes from low altitude sedimentary plains to erosional plains and plateaus of the
Precambrian shield with altitudes between 600 and 1000 m asl. The interface between the
sedimentary plain and the Precambrian shield is only revealed by a few rapids in the larger
rivers. Within the Precambrian shield four erosional plateaus, corresponding with 100, 200-
300, 400-500 and 600-800 m asl, can be distinguished. The plateaus at 200-300 and 600-800
m asl respectively, correspond with the erosion surfaces African II and I (Franqueville,
Fluvial processes have shaped the landforms in the recent past. Eolian, glacial or periglacial
processes did not affect the Cameroonian Precambrian shield.
The TCP research area is on the transition between the coastal plain and the Precambrian
shield forming the interior plateau (Segalen, 1967). As a result the TCP research area is
geomorphologically diverse. In the western part plains dominate whereas the eastern part is
mountainous. The altitude ranges from 40 m asl in the western part to more than 1000 m asl
in the eastern part. The central area is intermediate in both landform and altitude. A more
elaborate literature review on landforms in the TCP research area is presented in section 4.1.
The soils of Southwest Cameroon have been described and mapped at scale 1 : 2 000 000
and 1 : 1 000 000 (Segalen, 1957; Martin & Segalen, 1966). Three major soil types are
distinguished. The deep, moderately well to well drained, yellowish brown tropical clay
soils; `les sols ferrallitiques jaunes sur les roches acides (gneiss)' in the original French
denomination, are the most widespread. These soils have high contents of sesquioxides (iron
and aluminum) and are low in exchangeable bases.
The deep, well drained, reddish brown tropical clay soils; `les sols ferrallitiques rouges sur les
roches acides' are restricted to the eastern part of Southwest Cameroon. The gneisses and granites
of the `Complexe Calco-magnésien' coincide with this soil type (Touber, 1993a). The chemical
properties are similar to the yellowish brown tropical clay soils.
The third soil type are the alluvial soils which are restricted to alluvial plains and valley bottoms.
Although not covering large surfaces, this soil type is very distinct. It is often mapped in
association with the yellowish brown and reddish brown tropical clay soils. The alluvial soils are
characterized by greyish colours or mottling due to permanently high or variable groundwater
levels. Texture varies with depth.
The soils in Southwest Cameroon are generally acid, have no weatherable minerals and the cation
retention by the mineral soil fraction is low, leading to chemically poor soils. The soil fertility
mainly depends on the organic matter that is concentrated in the upper 50 cm of the profile.
Removal of the biomass and erosion of the topsoil seriously reduces the fertility (Driessen &
Dudal, 1989). The soils are prone to strong phosphorus fixation and aluminum toxicity.
The physical properties of the soils are favourable for agriculture: deep soils with high
permeability and a stable microstructure. With exception of the shallow and sandy soil types the
soils are hardly susceptible to erosion. Their friable consistence under most conditions makes
them easy to work. The well-drained tropical clay soils may in times be droughty because of their
low water storage capacity (Driessen & Dudal, 1989). The physical characteristics, i.e. soil
structure, permeability and infiltration, deteriorate by forest exploitation (e.g. on account of the
use of heavy machinery).
A more elaborate literature review on soils in the TCP research area is presented in section 5.1.
Southwest Cameroon forms part of the Guineo-Congolian domain which consists of dense humid
evergreen forests. The area forms a belt along the Bay of Biafra. The width of the belt increases
from 100-150 km in the north to 200-250 km in the south (Letouzey, 1985). The Guineo-
Congolian domain is divided by altitude in a submontane zone (altitudes between 800 and 2200
m asl) and a zone with low and medium altitudes (between sea level and 800 m asl).
The submontane part of the Guineo-Congolian domain is almost completely restricted to the
Mount Cameroon area and only very small surfaces are found scattered throughout Southwest
Cameroon on individual upheavals surpassing 800 m asl. Most submontane forests have been
degraded as a result of shifting cultivation and logging activities.
In Southwest Cameroon, the lower part of the Guineo-Congolian domain can be divided into four
districts; the Littoral Atlantic district, the Biafran Atlantic district and the Central-oriental
Atlantic district with humid evergreen forests, and one district with semi-deciduous humid forests
(Letouzey 1968; 1985). In Figure 2.5 the location of the different districts is roughly indicated.
Because of the various human activities mentioned above, the vegetation in large parts of
Southwest Cameroon has changed drastically. Forests in different stages of degradation are found
close to towns and villages, along access roads, and in logged forest. The floristic composition of
the secondary vegetation is very distinct and incorporates many species which can be
characterized as `pioneer species' and which are found in disturbed vegetation throughout the
Guineo-Congolian domain, e.g. Musanga cecropioides, Myrianthus arboreus and Homalium
species. Large recent clearings are typically overgrown with the stout herb Chromolaena
odorata. Moreover, depending on the intensity of clearing, many relicts of the previous forests
are found reflecting the characteristics of each of the phytogeographic districts.
A more elaborate literature review on vegetation in the TCP research area is given in section 6.1.
The tropical moist forest area of Cameroon possesses high levels of endemic fauna and flora. The
Lower Guinea centre of endemism (Gartlan, 1989) stretches from SE Nigeria in the north to
Gabon in the south. A subdivision is made into the Cameroon refuge, centring around Mount
Cameroon, and the West Equatorial refuge south of the Sanaga river. The two refuges are
important with respect to the conservation of biodiversity.
Approximately 132 species of mammals are found in the humid forests of Cameroon (Vivien,
1991), among which endangered species like elephant (Loxodonta africana cyclotis), western
lowland gorilla (Gorilla gorilla gorilla), chimpanzee (Pan troglodytes troglodytes), mandrill
(Mandrillus sphinx), African leopard (Panthera pardus), forest buffalo (Synceras caffer nanus)
and bongo (Tragelaphus eurycerus) (IUCN, 1988). No systematic census of the mammals of the
TCP area has taken place. Van Dijk (1997), in her study on non-timber forest products,
interviewed villagers on the use and presence of `bush meat'. Her survey reveals that, although
the elephant has become extinct, the TCP research area still harbours gorillas, chimpanzees and
mandrills. Bekhuis (1997) studied, within the framework of the Lu1 project, the habitat
requirements of some larger mammal species.
Some 849 species of birds are found in Cameroon (Louette, 1981). A total of 390 bird species are
known to occur in the Korup National park and its surroundings in the South-West Province,
Cameroon. Although the avifauna of this area is still incompletely known, it is already among the
ornithologically most diverse lowland forest sites in Africa (Rodewald et al., 1994). Some 48 of
these species are considered globally threatened or near-threatened. The avifauna of the TCP
research area has neither been studied intensively nor systematically. The legacy of a few
individuals has resulted in the drafting of a preliminary species list of the TCP research area. The
total of identified species is at present 96. In Annex VI all recorded species are listed.
The human population of Southwest Cameroon is concentrated in a few urban centres like Edéa,
Kribi and Ebolowa, and in numerous villages along the main access roads. Population density in
the rural forest areas averages 5 habitants per km
(Foahom & Jonkers, 1992).
The ethnic composition of the population of the TCP research area is diverse. Approximately
90% of the population are Bantus, belonging to the Bulu, Fang, Bassa and Ngumba tribes. They
live in villages along the roads. The Bantus practice shifting cultivation, but other activities such
as hunting, fishing and gathering of Non Timber Forest Products (NTFPs) are also
important. Approximately five percent of the population are Bakola (or Bagyeli) pygmies.
They are mainly forest dwelling hunters and gatherers, although they seem to be in the
process of sedentarization. Shifting cultivation is practised by Bakola but is not widespread.
The life style of the Bakola is seriously threatened by the ongoing logging and shifting
cultivation activities in the area.
Traditionally Bantu and Bakola have all sorts of socio-economic relationships. Bakola
groups have kinship ties with certain villages which arranges the mutual use of forest areas
and protects it from outsiders. Bakola provide agricultural labour and bush meat to the Bantu
farmers in return for agricultural products, like cassava and bananas, and increasingly for
money. Bakola traditional doctors are regularly consulted by the Bantu villagers. In recent
years the relation of the Bakola with their Bantu kin is becoming less exclusive and Bakola
are now known to sell NTFPs directly to traders outside the region (pers. comm., F. Tiayon,
Traditionally men and women of rural communities of Southwest Cameroon have specific
tasks with regard to land use. In Bantu villages, the women are responsible for the
cultivation of crops, the preparation of food and the general housekeeping. Men are
responsible for the clearing of forest and old forest fallow for agricultural fields, hunting and
the cultivation of cash crops. Labour provision to logging and other companies is restricted
to men. The collection of NTFPs in the vicinity of the village and fields is done by women,
whereas those from the virgin forest are gathered by men.
A gradual transformation of the rural communities from subsistence to (partially) market
oriented economy, is taking place in the last decade and is strongly influenced by the
improved infrastructure. This will trigger changes in the relation between men and women
and as a result the dynamics of land utilization by the local population may change (pers.
comm., I. Hijman, 1996).
2.10 LAND USE
The main economic activity in the area is timber exploitation. Most of the forest within the
TCP research area has at least twice been selectively logged by national and international
companies, among them the Dutch GWZ. Logging concessions are granted for a one to three
year period. The logging of the forest involves the construction of logging roads with
bulldozers and graders. Log extraction from the forest is done by wheeled skidders and
crawler tractors. Present logging activities focus on three species; Azobé (Lophira alata),
60% of the extracted volume), Tali (Erythrophleum ivorense) and Padouk (Pterocarpus
soyauxii). Only trees with diameters at breast height (dbh)
≥ 80 cm and straight boles of at
least six meters are considered worthwhile. The resulting average logging intensity is low,
i.e. 10 m
representing 0.7 trees, compared with regions like Malaysia where on average
15 trees per hectare are removed. The felling and extraction of the logs from the stand are
estimated to affect less than 15% of the surface (pers. comm. G.J.R. van Leersum, 1996).
Agriculture is an important land use in the TCP research area. The traditional shifting
cultivation system involves the clearing and burning of primary and old secondary forest just
before the rainy season and the planting of cucumber, maize, cassava, coco-yam and
plantain. With decreasing soil fertility, the tending and harvesting of a field gradually stops and
the land is left fallow after a maximum of five years. The former agricultural fields are then
colonized by a forest vegetation. The biomass accumulation of the secondary vegetation restores
soil fertility. The traditional shifting cultivation cycle is gradually being transformed by the
introduction of the chain saw, the limited amount of available labour and the scarcity of new land
within reach of the village. More and more farmers are clearing young fallows for agricultural
fields. They plant groundnut and cucumber in association with coco-yam, cassava and maize. The
total surface of this rotational fallow system is less than ten hectares per farmer (pers. comm., M.
NTFPs are a major source of food, construction materials, agricultural and household utensils,
medicines and cash for the local population of Southwest Cameroon. The gathering of NTFPs is
for the Bantu population supplementary to agriculture. For Bakola it is the mainstay. Surveys on
NTFP collection have been carried out in the neighbouring Campo-Ma'an area and in the TCP
research area. Some 500 plant species were recorded in the TCP area alone that provided a total
of nearly 1200 different uses. The trade in NTFPs is an important source of income for the local
population. The most traded NTFPs in the TCP area are for the Bantu population: oil palm
(Elaeis guineensis), bush mango (Irvingia gabonensis) and the almond-like `Njansang'
(Ricinodendron heudelotti). The Bakola collect and trade the fruits of the liana (Strophanthus
gratus), honey and several oil containing nuts (e.g. Panda oleosa and Poga oleosa) (Dounias,
1993; pers. comm. H. van Dijk, 1996).
Next to subsistence agriculture, cacao is cultivated for cash revenues by mainly Bantu farmers