Raphia `species 2' are the most common species. In some localities the abundance of Draceana spp.
is remarkable. The distribution of herbaceous plants is very irregular. Very dense patches alternate
with stretches with virtually no terrestrial plants. Palisotha mannii, Halopegia azurea and
Sarcophrynium prionogonium grow gregariously and often dominate the herb layer. Other frequently
occurring species are Curcuma longa, Stylochiton zenkeri, Draceana phrynioides and Rektophylium
The community is found in valley bottoms and along creeks and rivers throughout the TCP
research area. It covers fair surfaces of the dissected plains of the western part of the study area.
Forests of the Carapa - Mitragyna community are found between 40-700 m asl. The vegetation is
restricted to the soil type `valley bottoms', which are poorly to imperfectly drained soils which
tend to be shallow and having a thin organic layer.
The vegetation of this community group are broad-leaved tropical ombrophilous swamp forests
and broad-leaved tropical ombrophilous alluvial forests (UNESCO, 1981). Due to the small scale
of Letouzey's phytogeographic map, i.e. 1 : 500 000, the small areas covered by swamp
vegetation have not been accounted for individually. They appear as complexes with the
surrounding forest types.
6.4.6 Xylopia - Musanga community (IV)
The Xylopia - Musanga community is a young secondary forest. Differentiating species of this
community are Xylopia `group 1', Fagara macrophylla, Palisota ambigua, Thaumantococcus
`group 1', Megaphrynium secundiflorum and Ancistrophyllum `group 1'.
In general, the vegetation consists of three distinct strata: tree, shrub and herb layer. Often relics
of the undisturbed forest are presents. In general the external foliage cover of these emergents is
less than ten percent. The tree layer is open (40-50%) and is only 15-25 m high. Dominant
growth forms are evergreen broad-leaved trees and palms. The most common species are
Musanga cecropioides, Pycnanthus angolensis, Coelocaryum preussii, Funtumia elastica,
Xylopia `group 1', Tabernaemontana crassa, Rauvolfia macrophylla and Ricinodendron
heudelotti. Other frequently occurring species are Fagara macrophylla, Vitex grandifolia and
Macaranga `group 1'. The shrub layer is 2-7 m high and often merges into the tree layer. It is
closed and infested with thorny lianas such as Ancistrophrynium secundiflorum and Haumania
danckelmanniana. The trees in this layer often have thorns, e.g. Fagara macrophylla. Stilt roots
are abundant. Xylopia `group 1', Alchornea floribunda, Anthonotha macrophylla, Megaphrynium
secundiflorum and Ouratea flava are the most common species. The herb layer is rather open and
has an average height of 50 cm. Broad-leaved herbs tend to dominate. Characteristic species are
Stylochiton zenkeri, Thaumantococcus `group 1', Haumannia danckelmanniana, Palisotha
ambigua, Rektophylium `group 1' and Stipularia africana.
This community is the typical fallow vegetation in shifting cultivation areas and is found near
villages and along the main access roads, throughout the TCP area. To a lesser extent it is found
in logged-over forests. It is induced by human activity and appears to be rather insensitive to soil
and landform variation. The Xylopia - Musanga community forms a transitional stage between
the Macaranga - Chromolaena community (V) and old secondary forest types (IIa, IIb, IIc and
III; all p.p.). It develops some five years after fallow. The vegetation can be typified as evergreen
broad-leaved woodland in the UNESCO classification of vegetation (UNESCO, 1981). The
distribution of the Xylopia - Musanga community within the TCP research area coincides
with Letouzey's type n
251, i.e. remnants of strongly degraded evergreen forests.
Physiognomy and species composition is also comparable although some elements of
Letouzey's `strongly degraded remnants of semi-deciduous forest' (type n
169) are also
6.4.7 Macaranga - Chromolaena community (V)
The Macaranga - Chromolaena community forms thickets on recently abandoned fields and in
cacao plantations. The differentiating species of this community are Macaranga `group 1',
Chromolaena odorata, Albyzia zygia, Costus violaceus, Milicia excelsa, Rauvolfia vomitoria and
Ceiba pentandra. In addition, some cultivated species are still present, e.g. Trifolium `species 1'
(groundnut), Manihot esculenta (cassava), Colocasia `species 1' (coco-yam) and Musa `species 1'
In the shrub like vegetation of the Macaranga - Chromolaena community three (sometimes only
two) structural layers can be discerned. The tree layer is very open (20-40%) and is very low (8-15
m). The canopy is formed by trees and palms. The most frequent species are, in descending order,
Musanga cecropioides, Albyzia zygia, Pycnanthus angolensis, Antocleista vogelii and Elaeis
guineensis. The most characteristic feature of the vegetation of this community is the very dense
and high shrub layer (up to five meters) in which broad-leaved robust herbs are by far the
dominant growth form. Additionally, broad-leaved trees, palms, lianas are also present. The
vegetation is literally overgrown by Chromolaena odorata. Other non-woody species are Costus
violaceus, Aframomum alboviolaceum, Megaphrynium secundiflorum, Thaumantococcus daniellii
and Palisota ambigua. Characteristic woody species of the shrub layer are Funtumia elastica,
Macaranga `group 1', Rauvolfia macrophylla, Eleais guienensis and Fagara macrophylla. Also
many residual agricultural crops are present, e.g. Musa parodisiaca, Manihot esculenta, Colocasia
sp. and Carica papaya. Underneath the dense shrub layer, a very open (20%) and low herb layer
(20-40 cm) can be distinguished. Here, herbs, ferns and seedlings form the majority of the plant
life encountered. Often Trifolium sp. is abundant.
The Macaranga - Chromolaena community is found in the vicinity of villages and roads and is
strongly related to recent agricultural activities. It is most common on the dissected plains in the
western part of the TCP area, and in the surroundings of Akom II. It does not occur (yet) at
altitudes above 600 m asl.. The vegetation is typical for recently abandoned fields, approximately
between one and five years after cultivation. Also Cacao (Theobroma cacao) plantations with a
lush understorey of broad-leaved herbs are part of this community group. Many transitions
between this community and young secondary forests (community IV) are found.
The Macaranga-Chromolaena community can be classified as an evergreen broad-leaved thicket
according to the UNESCO vegetation classification (1981). Because of the small scale of his
phytogeographic map, Letouzey (1985, see Figure 6.1) incorporates these recently abandoned
agricultural fields in type n
251, i.e. remnants of strongly degraded evergreen forest.
Physiognomy and species composition correspond closely to what he describes as `ultimate
degraded remnants of evergreen and semi-deciduous forest' (type n
7 LANDSCAPE ECOLOGICAL MAP
Four altitude zones, seven different landforms, four main soil types and seven broadly defined
plant communities form the basis of the reconnaissance landscape ecological map of the TCP
research area (Annex I.) The legend of the landscape ecological map is based on altitude,
landform, soil and vegetation, and has a hierarchical structure. A total of 14 main land mapping
units is discerned. These units are further subdivided based on vegetation characteristics,
resulting in 34 mapping units. Each mapping unit is represented by a code, which is a
combination of the ecological zone (A to E) and the predominant landform (v, pd, u1, u2, h1, h2
and m). The legend is presented on the landscape ecological map (Annex 1).
Five ecological zones are identified and form the highest level of division of the legend. Soil
drainage and altitude are the differentiating criteria on this level. Four of the ecological zones
have well to moderately well drained soils. The altitude ranges of these four ecological zones are:
> 700 m asl (zone A), 500-700 m asl (zone B), 350-500 m asl (zone C) and < 350 m asl (zone D).
The fifth ecological zone (zone E) comprises swamp forests on poorly to very poorly drained
soils. Altitude is not differentiating for this zone. Although swamp environments are found
locally throughout the study area, only those of sufficient size to be mapped individually on
reconnaissance scale are considered part of this ecological zone. Small swamp areas occur as part
of the vegetation and soil complexes within the zones B, C and D.
Landform has been introduced at the second level of the legend. Seven landforms are discerned:
valley bottom (v), dissected erosional plain (pd), rolling upland (u1), hilly upland (u2), isolated
hill (h1), complex of hills (h2) and mountain (m). Their characteristics are discussed in chapter 4.
At the third level of the legend the characteristics of soils and vegetation of each landform unit
within a particular ecological zone are given. These aspects are described in the chapters 5 and 6.
7.2 LAND USE
The aerial photographs, on which the present landscape ecological map is based, were taken in
1983-1985. Recent changes in vegetation cover can therefore not be accounted for. Field
observations suggest that especially dynamic forms of land use such as shifting cultivation and
commercial logging have affected the vegetation to a considerable extent during the last ten
The natural vegetation of the above described landscape ecological units has been affected by
agricultural practices. Based on the 1983-85 aerial photographs a subdivision of the land mapping
units into `relatively undisturbed areas', `low intensity shifting cultivation areas' and `high
intensity shifting cultivation areas' is made. The degree of disturbance in each unit determines the
composition of the vegetation. Relatively undisturbed areas are characterized by the (near
complete) absence of agricultural fields. These areas cover about 70% of the TCP area or 116 170
ha. Within the low intensity shifting cultivation areas actual and recently abandoned agricultural
fields cover less than 20% of the unit. Young secondary vegetation accounts for another 20%.
The low intensity shifting cultivation covers about 18% or 29 800 ha. In the high intensity
shifting cultivation areas actual fields and recently abandoned agricultural fields cover more
than 40% Additionally, more than 20% of the unit is young secondary forest. The high
intensity shifting cultivation takes up about 13% of the TCP area or 21 360 ha. Within the
shifting cultivation areas patches of forest are found, both undisturbed and disturbed.
Unlike shifting cultivation activities, which are strongly concentrated in specific areas, the
impact of logging on the forest vegetation could not be mapped accurately. This is primarily due
to scale problems. Moreover, with time the differences between extensively logged-over forest
and `virgin' forest stands become quite subtle, whereas the seven plant communities given in the
legend are broadly defined. Each of the five types of relatively undisturbed forest (I, IIa, IIb, IIc
and III) in fact comprise both virgin stands and various regeneration stages of old secondary
forest. During the second phase of the LU1-project the distribution and floristic composition of
these `variants' are studied in more detail.
7.3 LAND MAPPING UNITS
The characteristics of the fourteen main land mapping units of the landscape ecological map are
presented in the following section. For more elaborate descriptions of the landforms, soil types
and plant communities reference is made to the chapters 4, 5 and 6. The two table below
summarize the spatial coverages of each main mapping unit.
Table 7.1a Surface areas in ha of the main land mapping units.
area in h
% of total
Table 7b Extent of the areas influenced by shifting cultivation
Intensity of shifting cultivation
% of total
No to hardly any (u)
Low intensity (l)
High intensity (h)
7.3.1 Am: mountains above 700 m asl, well drained soils
The Am land mapping units coincide with the Bingalanda mountain range in the eastern part of
the TCP area, with altitudes between 700 and 1000 m asl. They cover a surface area of 10,000 ha.
The mountainous area is strongly dissected and has steep outer slopes. Valley bottoms are narrow
and cover only very limited surfaces. The soils are very clayey and belong to the Nyangong type.
The predominant forest type is the submontane Maranthes-Anisophyllea community (I). In
general, the vegetation is not affected by human activity.
7.3.2 Ah1: isolated hills above 700 m asl, well drained soils
These mapping units are found along the fringes of the Bingalanda massive in the eastern part of
the TCP area where they cover some 880 ha. The altitude of the isolated hills vary from 700 to
900 m asl. Valley bottoms are not included in this unit. The soils are very clayey (Nyangong).
The predominant forest type is the submontane Maranthes - Anisophyllea community (I). Human
activities have not altered the vegetation in these units.
7.3.3 Bh2: complex of hills between 500 and 700 m asl, well drained soils
Mapping units Bh2 are complexes of hills between 500 and 700 m asl, and are found in the
strongly dissected eastern part of the TCP research area. They cover large surfaces just west of
the Bingalanda mountain range and have a general SW-NE orientation. In addition, Bh2 units are
found in the southwestern part of the TCP research area, where they form the foothills of the
mountain range that is situated west of the TCP research area. The total surface area of these
mapping units is some 13,890 ha. The dominant soils are very clayey (Nyangong). Valley
bottoms are narrow and cover only limited surfaces. The vegetation is predominantly primary and
old secondary lowland forest of the Podococcus-Polyalthia community (IIa). Human activities
have not altered the vegetation of these units.
7.3.4 Bh1: isolated hills between 500 and 700 m asl, well drained soils
These mapping units are found scattered as small patches in the eastern part of the TCP area.
Although their total area does not cover more than 3 820 ha, the isolated hills form a
characteristic aspect of the landscape. The elevation of the hills is between 500 to 700 m asl. The
soils are very clayey and belong to the Nyangong type. Valley bottoms are almost completely
absent. The vegetation is predominantly primary and old secondary lowland forest of the
Podococcus-Polyalthia community (IIa). Human activities have not altered the vegetation of
7.3.5 Bu2: hilly uplands between 500 and 700 m asl; well drained soils
The hilly uplands of the Bu2 units cover some 19,700 ha. They are located at the foot of the
Bingalanda mountain range in the eastern part of the TCP area and in the northeastern part of the
area. The uplands are strongly dissected and valley bottoms are estimated to cover between 5 and
10% of their surface. The soils are an association of very clayey Nyangong soils and the clayey
Ebom ones. The predominant vegetation type of these units is the primary and old secondary
lowland forest of the Podococcus - Polyalthia community (IIa). The valley bottoms are
characterized by poorly drained soils and by the swamp forest of the Carapa - Mitragyna
The units are to a limited extent affected by agricultural practices. Only along the roads some
low intensity encroachment is visible on the 1984-85 air photo's. In these areas, especially near
the villages Nyangong and Ebemvok, the composition of the vegetation has gradually been
changing into a mosaic of thicket of the Macaranga - Chromolaena community (V), young
secondary forest of the Xylopia - Musanga community (IV), and lowland forest of the
Podococcus - Polyalthia community (IIa).
7.3.6 Bu1: rolling uplands between 500 and 700 m asl; well drained soils
Rolling uplands between 500 and 700 m asl are only found in the most eastern part of the TCP
area, where they cover a total surface area of 5,400 ha. The rolling uplands are moderately
dissected and valley bottoms are estimated to cover 10 to 15% of these mapping units. In places,
these valley bottoms are sufficiently large to be mapped individually. The soils form an
association of Nyangong and Ebom types. The valley bottoms are typically poorly to very
poorly drained and are occupied by swam forest of the Carapa - Mitragyna community (III).
The Bu1 units are affected by human activities especially near the village of Nyangong a large
area with low intensity shifting cultivation area has been discerned. Primary and old secondary
lowland forest of the Podococcus-Polyalthia (IIa) community is the predominant vegetation of
the relatively undisturbed areas. The shifting cultivation areas are characterized by a vegetation
mosaic that contains obviously disturbed lowland forest of the Podococcus -Polyalthia
community, young secondary forest of the Xylopia - Musanga community (IV) and thicket of the
Macaranga - Chromolaena community (V).
7.3.7 Ch1: isolated hills between 350 and 500 m asl, well drained soils
The isolated hills form a characteristic aspect of the central and northern region of the TCP area,
which is mainly composed of uplands. The characteristically scattered hills cover a total surface
area of 4,520 ha. Within the Ch1 units no valley bottoms are found. The soils are predominantly
clayey and are classified as Ebom soils. The vegetation is primary and old secondary forest of the
Strombosia - Polyalthia community (IIb). Human activities have not affected the vegetation of
these units, most likely because of the steep slopes,
7.3.8 Cu2: hilly uplands between 350 and 500 m asl; well drained soils
These mapping units occupy considerable surface areas, i.e., 25,070 ha, in the central and
northern regions of the TCP area. The general orientation of these mapping units is SW-NE. The
uplands are strongly dissected and an estimated 5 to 10% of their surface are covered by valley
bottoms. The soils of the higher parts are clayey (Ebom type) and those of the valley bottoms are
typically poorly to very poorly drained. The vegetation of the well drained part of the Cu2 units
is primary and old secondary lowland of the Strombosia - Polyalthia community (IIb). Swamp
forest of the Carapa - Mitragyna community (III) covers the valley bottoms.
Shifting cultivation is restricted to the southern edge of the unit near the villages of Adjab and
Akom II and to the northern parts and is generally of low intensity. The vegetation in
these areas is a mosaic of obviously disturbed lowland forest of the Strombosia - Polyalthia
community (IIb), and young secondary vegetation of the Xylopia - Musanga community (IV),
and the Macaranga - Chromolaena community (V). Furthermore it is observed that most of the
forest has been logged in the recent past.
7.3.9 Cu1: rolling uplands between 350 and 500 m asl; well drained soils
The rolling uplands between 350 and 500 m asl also occupy considerable surface areas, i.e.
31,270 ha, in the central and northern regions of the TCP area. With the mapping units Cu2
(hilly uplands) they form the major land mapping units of this regions. Both units have a
similar SW to NE direction and are found to alternate. Some 10 to 15% of the rolling
uplands are occupied by valley bottoms. The dominating soils of the slope and summit areas
are clayey Ebom soils, whereas the soils of the valley bottoms are typically poorly to very
poorly drained. The well drained areas are covered by primary and old secondary lowland
forest of the Strombosia - Polyalthia community (IIb) , whereas the vegetation of the valley
bottoms belongs to the Carapa - Mitragyna community (III).
Near villages and roads considerable parts of the Cu rolling uplands are occupied by high
intensity shifting cultivation. The vegetation in these areas is characterized by patches of
obviously disturbed lowland forest of the Strombosia - Polyalthia community (IIb) and by a
mosaic of young secondary vegetation: the Xylopia - Musanga community (IV), and the
Macaranga - Chromolaena community (V). According to the aerial photographs, the
vegetation outside the shifting cultivation areas units is relatively undisturbed. Field
observations, however, suggest that considerable parts of the forest have been exploited for
timber. Due to the lack of recent remote sensing material the extent of logging could not be
7.3.10 Dh1: isolated hills below 350 m asl, moderately well drained soils
Isolated hills below 350 m asl are restricted to the western part of the TCP area, where they
are sparsely scattered. They form although their a total surface area (3,310 ha), small but
characteristic aspects of the landscape. Within the units no valley bottoms are found. The
predominant soils are moderately well drained, have sandy topsoils and up to 40% clay in
the subsoils and are classified as Ebimimbang soils in the TCP soil classification. The
predominant vegetation of these units is primary and old secondary lowland forest of the
Diospyros - Polyalthia community (IIc). The vegetation of the isolated hills with their steep