Upper Guinea Evergreen Rain Forest

These forests are confined to the highly humid southern and western areas where rainfall can exceed 4000 mm per year. They have an evergreen aspect throughout the year and only during a short period between November and January can a few deciduous trees be seen in the emergent and upper canopies. Three stories can usually be identified. The upper canopy, which often exceeds 30 m, typically includes Lophira alata, Parkia bicolor, Piptadenia africana, Terrietia utilis and endemic or near endemic species such as Cynometra ananta (Fabaceae), Coula edulis (Olacaceae), Daniellia thurifera, Gilbertiodendron preussi (Fabaceae), Dialium aubrevillei (Fabaceae), Drypetes aylmeri (Euphorbiaceae), Erythrophleum ivorensis (Fabaceae), Khaya ivorensis (Meliaceae), Scaphopetalum amoenum (Sterculiaceae) and Soyauxia grandifolia (Medusandraceae). The lower stories usually comprise Cola chlamydantha, Diospyros sanz-minika, Funtamia africana, Pentadesma butyracea, Protomegabaria stapfiana, Strombosia pustulata together with endemic species such as Allanblackia parviflora (Hypericaceae), Calpocalyx brevibracteatus (Fabaceae) and the ebony trees Diospyros cooperi, D. heudelotii and D. vignei (Ebenaceae). The shrub layer is often sparse but may include Bertiera racemosa, Heisteria parvifolia, Randia hispida and the endemic Mussaeada chippii (Rubiaceae). Likewise, herbaceous ground layer species are scarce but the sedge Scleria barteri may become extensive when the tree canopy is more open. Other herbaceous species include various pteridophytes such as Gleichenia linearis, Lygodium macrophyllum, Lycopodium cernuum and Selaginella myosurus. Among the many lianas and creepers are Alafia barteri, Baissea multiflora, Combretum comosum, Griffonia simplicifolia and Landolphia owariensis. The epiphytes are mainly pteridophytes such as Arthropteris orientalis, Dynaria laurentii, Microsorium punctatum and Platycerium angolense, or orchids such as Bulbophyllum ssp. These forests are also of consierable interest for the presence of the endemic Pitcairnia feliciana, the only Old World member of the American family Bromeliaceae, and Rhipsalis cassutha (Cactaceae), the only cacti found in the Old World.   

 

Upper Guinea Moist Semi-Deciduous Forest

Structurally these are similar to the rain forest but show a greater degree of deciduousness, and in fact, between October and April many of the trees in the emergent and upper canopies lose their leaves. They are situated in the slightly dryer zones north of the rain forest. However, between the two there is a large transition zones known as the Lophira -Triplochiton association. This forms a belt some 10 to 30 miles broad and commonly includes Daniella ogea, Lophira alata, Triplochiton scleroxylon and the endemic or near endemic Hymenostegia afzelii (Fabaceae). This eventually gives way to a Celtis-Triplochiton association, which is considered to be the climatic climax of the semi-deciduous zone. Here Celtis species, such as C. adolfi-frederici, C. mildraedii and C. zenkeri become more abundant and the near endemic Cyclodiscus gabonensis (Fabaceae) makes its appearance, while other emergent or upper canopy species include Cola gigantea var. glabrescens, Nesogordonia papaverifera, Pterygota macrocarpa and Sterculia oblonga.  These forests make up about half total area of forest within this BioProvince. At the northern limit of deciduous forest is a transition zone to dryer habitat known as the Antiaris-Chlorophora forest association, which eventually gives way to savannah woodland beyond the boundary of this BioProvince. Togoland forest is included in this association. Although Celtis and Triplochiton remain common, Antiaris africana and Chlorophora excelsa become more frequent here than in any other part of the forest. The understory commonly includes the two endemic or near endemic trees Chidlowia sanguinea (Fabaceae) and Talbotiella genti (Fabaceae), while other endemic or endemic trees include Anopyxis klaineana (Rhizophoraceae), Terminalia ivorensis (Combretaceae) and the oil palm Elaeis guineensis (Arecaceae).

Further information required.

 

References

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