[en] Landscape Ecological Survey of the Bipindi-Akom II ... - ITTO

6.4.2 Podococcus Podococcus - Polyalthia Polyalthia community (lIa)
The Podococcus - Polyalthia community is a primary and old secondary lowland forest type; it is
found at at altitudes between 500 and 700 m as!. Differentiating species are are Hymenostegia ajzeilii,
Podococcus barteri, Crotonogyne preussii, Tabernaemontana 'species 1', Culcasia dinklagei, dinklagei,
Duboscia macrocarpa and Petersianthus africana.
At least four principal strata characterize the physiognomy of the Podococcus - Polyalthia
community, although their boundaries are often difficult to establish. establish. Large trees, often surpassing
55 meters in height, form the open (20 -30% cover) emergent layer. Klainedoxa microphylla and
Monopethalanthus spp. frequently dominate this stratum. The tree layer forms a canopy at 25 to
40 meters. The external foliage coverage is 60-80 %. Large trees are the most common growth
form and lianas appear to be be restricted restricted to the canopy and larger gaps. In In general the trees have a
smooth bark and only few have buttresses surpassing one one meter in height. The most common
species are are Pycnanthus angolensis, Uapaca guineensis, Strombosia 'group 1', Dichostemma
glaucescens, Plagiostyles africana, Santira trim era, era, Alstonia congensis, Hymenostegia Hymenostegia ajzeilii,
Desbordensia glaucescens and Scyphocephalium mannii. The shrub layer is relatively open,
covering 40-60% and between two and ten meters high. Shrubs and saplings of forest trees are
most common. Palms (Raphia 'species 1 ' and Podococcus barteri) are frequently present but never
dominate. Frequently found species of the shrub layer are Ptycopetalum petiolanum, Polyalthia
suaveolens, Scaphopetalum thonneri, thonneri, Scaphopetalum blackii, Plagiostyles africana, africana, Voacanga
'group 'group 1', 1', Dialium 'group 1', Coffea 'group 1 l' ' and Grossera 'group 1'. The herb layer is relatively
open, covering 40-50%, 40-50%, and often low. Broad leaved herbs, seedlings of trees, palms and lianas
are the major components. Frequently occurring species include Haumania danckelmannia,
Palisota mannii, Halopegia 'group 1', Calamus deeratus, Scaphopetalum thonneri, Rektophyllium
'group 1', Cercestis ivorensis, Trachyprhrynium braunianum and Podococcus barteri.
The Podococcus - Polyalthia community is found at altitudes altitudes between 500 500 and 700 m m as!. as!. It It is is
found found mainly in the southeastern zone of the TCP research area covering the slopes of the
Bingalanda mountain range. The soils soils are are mostly of the Nyangong type, i.e. very clayey soils with
40 to 80% clay in the B horizon. Land forms encountered are, in descending order of importance:
hilly uplands, complexes of hills, rolling uplands and isolated hills.
According to the UNESCO classification (1981) this community is a Tropical ombrophilous
lowland forest. The distribution of Podococcus - Polyalthia community in the TCP area coincides
with the eastern part of Letouzey's Atlantic Biafran forest with Caesalpiniaceae (no. 228) of which
the physiognomy and species composition composition indeed resemble the Podococcus - Polyalthia
community.
6.4.3 Strombosia Strombosia - Polyalthia community (lib)
The primary and old secondary lowland forest of the Strombosia - Polyalthia community is found
between 350 and 500 m as!. as!. On the the basis of the the present vegetation vegetation survey only two (weakly) (weakly)
differentiating differentiating species have have been been identified, identified, i.e. Grewia coriacea coriacea and Saccoglottis gabonensis. The
community is intermediate in both altitude and floristic composition between the two other primary
to old secondary lowland forest communities: the Podococcus - Polyalthia community (Ha) and
the Diospyros - Polyalthia community (IIc). (IIc).
The physiognomy physiognomy of the Strombosia - Polyalthia community is similar to that that of of the Podococcus­
Podococcus­
Polyalthia community. The complex structure of the forest has has four principal strata, including an
emergent layer, a tree layer, a shrub shrub layer and a herb layer. The height of the different strata varies
and the boundaries are often difficult to establish. The emergent layer is open (external foliage
cover < 20%) and reaches a height of 45-55 meters. The floristic composition composition is heterogeneous
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