Terms list
5.1 INTRODUCTION
The freshwater swamp is the dominant vegetation cover in the study area extending from Yokri to Sokebolou and Ogbotobo, and parts of Forcados.
Structure
Plate 4.1 provides a panoramic view of the swamp forest in the study area. The physiognomy of the fresh water swamp vegetation in the study area is varied and at different stages of re-growth and maturity. It varies from the secondary stage forests (55%) through the secondary forest regrowths (20%) and swamp forest regrowths (35%). Generally, the secondary forest reveals a vertical forest profile that is fairly differentiated into two distinct strata, the canopy str ata and the emerging strata; and is very visible around the VG 31, 33, 35 area (Plate 4.1). Here the canopy layer is dense with a vegetation cover of between 75 - 85%; the vegetation is of an average height of about 20 meters. Emerging above the forest canopy are fairly scattered trees reaching up to a height of about 26 meters.
The structure of vegetation can also be described based on the Raunkiaer life form classification system (1934). This system places emphasis on the form, and the dominance of the life forms of the plants present in a given vegetation system thus providing insight into the adaptation patterns, climate, terrain, and forest physiognomy. The life form spectrum of mature vegetation in the fresh water swamp of the study area, generally, indicates that the dominant life form is mesophanerophyte (80-90%) while nanophanerophytes (<2 meters height) makes up to 10% of the vegetation represented by the shade loving ferns, and hydrophytes including Cyrtosperma senegalensis, and Sagittaria sagittifolia (Plate 4.2). Epiphytes are also present on most of the palm trees dominated by tree ferns. Tree density reaches 900 trees/ ha. The forest floor was found to be more or less flooded during most parts of the year particularly in wet season. This is attributable to the low-lying terrain, abundant rainfall and numerous small streamlets that supply the terrain and establish the prevailing hydrologic regime.
There is a very low tree density (140 – 170 trees/ha) in areas of regrowth, and a more or less open forest canopy. In these areas, the shrub layer is dominated by shrubs and aquatic macrophytes.
Vegetation cover density however is over 75% in most places.
EIA REVALIDATION FOR FORCADOS-YOKRI INTEGRATED PROJECT (NAG WELLS)
Plate 4.1: A Panoramic View of the Fresh Water Vegetation Cover in the Study Area: (a) VG 31;
(b) VG 27; (c) VG 28; (e) VG 35; (f), (g) Swamp Forest Floor at Yokri.
Floristic Composition
A total of 33 species belonging to 23 families where identified in the forest. A species check list and classification is presented in Table 4.11. Due to this swampy terrain, it is common to find tree species possessing plank-like buttresses, stilt roots, or elaborate fibrous root system which help them to anchor on the swamp. This swamp however is observed to be palm (Elaeis guineensis) dominated (Plate 4.3a-e). Among the few emergent species are: Albizia adianthifolia, Uapaca guineensis, Cyclodiscus gabonensis, Pycnanthus angolensis, Dracaena mannii, and Alstonia
EIA REVALIDATION FOR FORCADOS-YOKRI INTEGRATED PROJECT (NAG WELLS)
boonei. A few oil palms are also seen emerging above the swamp forest canopy. Very common canopy tree species include Alstonia boonei, Ceiba pentandra, Lophira alata, Anthocleista djalonensis, Cleiostopholis patens, Fleroya ledermanii, and Cynometra megalophylla. Others are Cola sp., Tricoscypha arborea, Symphonia globulifera, Chytranthus talbotii, Terminalia superba and Musanga cecropioides. The shrub layer is dominated by Alchornea laxiflora (especially in forest gaps and margins), and saplings of tree species especially Alstonia boonei. Epiphytes such as Asplenium africanum, Nephrolepis biserrata, Diplazium sammatii grow on the forest trees along with other tree fern, while Cyrtosperma senegalensis and Sagittaria sagittifolia are among the hydrophytes on the swamp floor.
Table 4.11: Check List of Species in the Estuarine Water Swamp Vegetation Ecosystem.
SPECIES NAME COMMON
NAME
FAMILY ECONOMIC VALUE
TREES
Elaeis guineensis Oil Palm ARECACEAE Palm Oil, Kernel Oil, Palm Kernel cake, fibre for domestic handicraft Alstonia boonei Stool wood APOCYNACEAE Stool wood) Soft Light
wood. Carvings, light construction: canoe;
medicinal: Asthma, rheumatic pains, Snake poison. Cure veneral diseases. Antimalarial, aphrodisiac,
Antidiabetic,
antimicrobial and antipyretic properties.
Anthocleista vogelii Cabbage tree
GENTIANACEAE
Schummaniophyton magnificum
RUBIACEAE Antivenom
Cynometra megalophylla
CAESALPINIOIDEAE
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SPECIES NAME COMMON
NAME
FAMILY ECONOMIC VALUE
Albizia adianthifolia
LEGUMINOSAE Bark medicinal;
arthritis, rheumatism;
wood: construction
Uapaca guineensis EUPHORBIACEAE Red cedar, false
mahogany, Sugar plum.
Commercial hard wood durable. Edible sugary fruits: monkey delicacy; root aphrodisiac,
rheumatism, and piles.
Cyclodiscus gabunensis
LEGUMINOSAE Leaf: concoction for
treating inflammation of the vagina and uterus.
Pycnanthus anglolensis
MYRISTICACEAE Medicinal: Skin
infections; seed:
spice/additive; Leaves and stem: Diabetes 1 &
2. Bark decoction: treat wound, arthritis, leprosy, stomach ulcer, and antidote for poisoning.
Dracaena mannii AGAVACEAE Source of Dyes and
stains
Ceiba pentandra BOMBACACEAE Soft wood: Carvings,
light construction, ply wood, veneer, particle boards, hand dug canoe
; Kapok; bee tree;
Medicinal: in
preparations for leprosy,
Dysmenorrhoea, hypertension, fever,
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SPECIES NAME COMMON
NAME
FAMILY ECONOMIC VALUE
wound healing, and hypertension.
Lophira alata OCHNACEAE Commercial Hard
wood: One of the hardest and most resistant wood species Anthocleista
djalonensis
GENTIANACEAE Cabbage tree:
abortifacient, skin infections, antipyretic, antidotes
Cleistopholis patens ANNONACEAE
Fleroya ledermanii RUBIACEAE Furniture, pulp and
paper making.
Cola spp. STERCULIACEAE
Tricoscypha arborea
EUPHORBIACEAE Fuel wood, and poles.
Musanga cecropioides
Umbrella tree
EUPHORBIACEAE Medicinal: leprosy
Terminalia superba COMBRETACEAE Timber
Symphonia globulifera
CLUSIACEAE
Chytranthus talbotii SAPINDACEAE
Funtumia elastica Lagos rubber
APOCYNACEAE
SHRUBS
Alchornea laxiflora EUPHORBIACEAE
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SPECIES NAME COMMON
NAME
FAMILY ECONOMIC VALUE
Coffea canephora Wild Coffee RUBIACEAE Coffee beans
HERBS
Aframomum spp ZINGIBERACEAE
Costus afer ZINGIBERACEAE
Maranthocloa purpurea
MARANTHACEAE
AQUATIC MACROPHYTES
Cyrtosperma senegalensis
ARACEAE
Sagittaria sagittifolia
ARACEAE
Nymphaea lotus Water lilly NYMPHAEACEAE
FERNS
Asplenium africanum
ASPLENIACEAE
Nephrolepis biserrata
DRYOPTERIDACEAE
Diplazium sammatii
ATHYRIACEAE