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Afzelia africana Caesalpiniaceae

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Abstract

This biodiversity atlas of West Africa presents research results in a language understood by a broader public. Scientific data were collected over nine years by more than 470 participants of the BIOTA programme belonging to 13 countries, and by national experts. The Atlas covers Benin (Vol.I), Burkina (Vol.III). Each volume gives an overview on biodiversity at the scale of West Africa, and, for the respective country, detailed information on particular species, places, and national conservation issues.
6: Etat actuel de la diversité vegetale | Current state of plant diversity
74
descrIptIon of AfzeliA AfricAnA
Afzelia africana is a tree species from the Caesalpiniaceae fam-
ily. It is a large tree (up to 35 m) that is widespread in Western
Africa in the dry forest zones bordering the savanna. The hard
wood called Afzelia or doussié rouge” is sought for house build-
ing and especially for marine use. The species is overexploited
for wood and rewood. The stands are often cleared for agricul-
tural purposes.
utIlIsatIon of AfzeliA AfricAnA
Afzelia africana is a timber species with high forage, economic
and pharmacological values. Its leaves are harvested for graz-
ing during the dry season in the North of Benin. Stockbreed-
ers prune the branches to make them available to animals.
The bark seems very ecient in the treatment of many human
descrIptIon de AfzeliA AfricAnA
Afzelia aicana est une espèce d’arbre de la famille des Caesalpi-
niaceae. C’est un grand arbre (jusqu’à 35 m) répandu en Afrique
de l’Ouest dans les zones de forêts sèches à la limite de la savane.
Le bois dur appelé Afzelia ou doussié rouge est recherché pour les
constructions extérieures et en particulier pour la marine. Lespèce
est très exploitée comme bois d’œuvre, perches pour la construc-
tion, bois de service et bois d’énergie. Les peuplements sont sou-
vent défrichés à des ns agricoles.
utIlIsatIon de AfzeliA AfricAnA
Afzelia aicana est une essence de bois d’œuvre à haute valeur four-
ragère, économique et pharmacologique. Les feuilles de l’espèce
constituent des pâturages aériens surtout en saison sèche dans le
Nord du Bénin. Les branches sont élaguées par les éleveurs pour
les mere à la disposition des animaux. L’écorce serait très ecace
dans le traitement de beaucoup de maladies humaines. Pilées et mé-
langées au sel, elle favoriserait une bonne alimentation chez les bo-
vins. Par ailleurs, le bois est très recherché et surexploité. Du fait de
ces valeurs, l’espèce subit dans l’ensemble une pression anthropique
sévère au Bénin (Carte xxx).
cactérIstIques morphologIques de Af
zeliA AfricAnA au bénIn
Les diamètres moyens des individus de Afzelia aicana varient si-
gnicativement entre 30,61 cm à Pikiré à 69,29 cm à l’Okpara. On
distingue 10 groupes homogènes de classes de diamètre pour Afze-
lia aicana au Bénin. Les localités à très faibles diamètres moyens
sont majoritairement dans la zone Soudanienne tandis que celles
ayant des individus de grand diamètre sont dans les zones Gui-
néo-Congolaise et Soudano-Guinéenne (Tab. xxx). L’analyse de
variance des hauteurs de Afzelia aicana a montré une diérence si-
gnicative des hauteurs d’une localité à une autre. Les plus grandes
hauteurs moyennes sont enregistrées dans la zone Guinéo-Con-
golaise alors que les plus faibles hauteurs sont observées dans la
illnesses. Ground and mixed with salt, it seems to favour good
fodder for cattle. Moreover, the wood is highly demanded and
overexploited. As such, the species is under severe anthropic
pressure in Benin (Map xxx).
MorpholoGIcal characterIstIcs of AfzeliA Af-
ricAnA In benIn
The average diameters of Afzelia africana individuals vary signi-
cantly between 30.61 cm in Pikiré to 69.9 cm in the Okpara. We
distinguish 10 homogenous groups of diameter classes for Afze-
lia africana in Benin. Locations with very small average diame-
ters are in the Sudanian zone while the sites with large diameter
individuals are in the Guineo-Congolese and Sudano-Guinean
zones (Tab. xxx). Analysis of the variation of heights of Afzelia
africana has shown a signicant dierence of heights from one
location to another. The largest average heights were recorded
in the Guineo-Congolese zone while the lowest heights were
observed in the Sudano-Guinean zone and the Soudanian zone
where the pruning pressures are too high (Tab. xxx).
Achille Ephrem ASSOGBADJO
Romain GLELE KAKAI
Brice SINSIN Brice
Afzelia aicana
(Caesalpiniaceae)
1.10
Afzelia africana
(Caesalpiniaceae)
Bénin
75
n the Guinea-Congolese zone, the Lama forest has shown
an average diameter and height of 66.7 cm and 30.5 m
respectively.
dIstrIbutIon and ecoloGy of AfzeliA AfricAnA
In benIn
Afzelia africana is a widespread species and can be found in
the following countries: Benin, Burkina Faso, Cameroon, Cen-
tral African Republic, Côte d’Ivoire, Ghana, Guinea, Guinea-Bis-
sau, Mali, Niger, Nigeria, Uganda, Democratic Republic of the
Congo, Senegal, Sierra Leone, Soudan, Chad, and Togo. In Benin,
Afzelia africana is distributed over all latitudes (06°30 to 12°30
N). It is found in the dense semi-deciduous forests, savannah
woodlands and in some gallery forests. It is found in the North
of Benin beyond 08° N, especially in the tree savannas on later-
itic soils, and in saxicolous tree savannas with stony ground. The
species prefers the silty-sandy or silty-sandy-clay or sandy-silt
soils. Nevertheless, it is also found on clay soil (case of Lama). A
Zones climatiques
Diamètre moyen
en cm (n)
Average diameter
in cm (n)
Hauteur
moyenne
Average height
in m (n)
Soudano Guinéenne 48 (198) 10 (198)
Guinéo Congolaise 47 (160) 13 (160)
Soudanienne 42 (311) 9 (311)
Diamètre moyens et hauteur moyenne de Tab. 1.5: Afzelia aicana
par zone climatique. | Average diameter and height of Afzelia af-
ricana by climatic zone
n = nombre d’individus mesurés | number of individuals measured
zone Soudano-Guinéenne et la zone Soudanienne où les pressions
d’émondage sont trop élevées (Tab. xxx).
Dans la forêt de la Lama en zone Guinéo-Congolaise a révé-
lé un diamètre et une hauteur moyennes de 66,7 cm et 30,5 m
respectivement.
Afzelia aicanaFig. 1.6:
76
dIstrIbutIon et écologIe de AfzeliA Afri
cAnA au bénIn
Afzelia aicana est une espèce largement répandue qui se rencontre
dans les pays suivants: Bénin, Burkina Faso, Cameroun, Républi-
que Centre-Africaine, Côte d’Ivoire, Ghana, Guinée, Guinée-Bis-
sau, Mali, Niger, Nigéria, Ouganda, République Démocratique du
Congo, Sénégal, Sierra Leone, Soudan, Tchad, et Togo. Au Bénin,
Afzelia africana est répartie dans toutes les latitudes traversant le ter-
ritoire national (06°30 à12°30 N). Il s’agit d’une espèce rencontrée
dans les forêts denses semi-décidues, les savanes boisées et dans
certaines galeries forestières. Au Nord du Bénin au-delà de 08° N,
on la rencontre surtout dans les savanes arborées sur sols latériti-
ques et dans les savanes arborées saxicoles à sol caillouteux. Les
textures équilibrée (limono-sableuse et limono-argilo-sableuse) et
sableuse (sablo-limoneuse) sont celles sur lesquelles se développe
Afzelia africana. Néanmoins, on la retrouve également sur sol à tex-
ture argileuse – cas de la Lama. Il existe en peuplement pur en ré-
gion soudanienne dans les localités de Pikiré (Kérou) sous le nom
« Gbésson » c’est-à-dire forêt d’Afzelia aicana, de Wourouna et
de Tankoga (Kouandé).
statuts et menaces sur AfzeliA AfricAnA au
bénIn
Afzelia africana est considérée vulnérable selon les Catégories de
menaces de l’UICN. Au Bénin, trois niveaux de pression ont été
identiés pour Afzelia aicana :
le groupe I (Localités de la zone Guinéo-Congolaise : Lama, Sa-
miondji, Pobè, Mono et Kétou) qui représente les localités où
l’espèce subit une faible ou moyenne pression avec en moyenne
plus de 65 % d’individus intacts. Ces localités sont toutes situées
au Sud du Bénin et bénécient d’un statut de protection,
le groupe II (Localités de la zone de transition Soudano-Gui-
néenne : Tasso, Sakabansi, Kérémou, Okpara, Bétérou, Ségbana,
Bensékou, Agbassa, Dogo, Toui et Bessassi) qui représente les
localités à fortes pressions sur Afzelia africana et où les individus
intacts sont très rares ou absents,
le groupe III (Localités de la zone Soudanienne : Bembéréké,
Firou, Gbéba, Pikiré, Birni, Toucountouna,) qui est celui des lo-
calités à très fortes pressions et les individus intacts sont rares ou
absents.
pure population occurs in the Sudanian region around the lo-
calities of Pikiré (Kérou) under the name “Gbésson” or forest of
Afzelia africana, and in the localities of Wourouna and Tankoga
(Kouandé).
statutes and threats concernInG AfzeliA Afri-
cAnA In benIn
Afzelia africana is considered as vulnerable according to the
IUCN red list. In Benin, three levels of pressure have been identi-
ed for the species:
Group I: Localities of the Guineo-Congolese zone (Lama,
Samiondji, Pobè, Mono and Kétou) which represents the lo-
calities where the species is subject to low or average pres-
sure with on average more than 65 % of individuals intact.
These localities are all located in the South of Benin and
benet from a statute of protection.
Group II: Localities in the Sudano-Guinean zone (Tasso,
Sakabansi, Kérémou, Okpara, Bétérou, Ségbana, Bensékou,
Agbassa, Dogo, Toui and Bessassi) which represent the lo-
calities with strong pressure on the species and where the
intact individuals are very rare or absent.
Group III: Localities of the Sudanian zone (Bembéréké, Firou,
Gbéba, Pikiré, Birni, Toucountouna) which are the ones in
which the species is under a very high pressure and where
intact individuals are rare or absent.
In Benin, the level of pressure on Afzelia africana varies accord-
ing to the latitude and the protection statute of its habitats. Be-
tween 06°30 and 08° N (essentially Group I) - From the Guinean
coast to Zou (06°30 to 08°N) where Afzelia africana is observed
in its natural state the pressures can, essentially, be summa-
rized to the exploitation of the species for its wood. This has al-
ready caused the great scarcity of the species in some localities
of south of Benin. The most illustrative case is the Department
of Mono (Kouo) where an extreme rarity of the species has
been noted. Between 08° and 11°45 N (Essentially Groups II and
III), the pressure on the species is very high and, in the majority
of cases, caused by the animal breeders. Leaves and branches
pruning after the vegetation re in the dry season are the main
causes for the species mutilations. This is followed by the uses
for traditional pharmacopeia and the use for its wood.
Carte de distribu-Carte 1.2:
tion et de menace sur Afzelia
aicana au Bénin. | Map xxx:
Distribution and threats
map of Afzelia africana in
Benin. (Source : Sinsin et al.,
2004)
Groupe socio-
linguistique
Ethnic group
Noms locaux
Local name
Noms locaux Tab. 1.6:
donnés au Afzelia aicana
au Bénin. | Local names of
Afzelia africana in Benin.
Gousse de Fig. 1.7: Afzelia aicana montrant les graines à l’intérieur | Afzelia africana pod showing
the seeds inside.
Graines de Fig. 1.8: Afzelia aicana | Afzelia africana seeds.
Afzelia aicana Fig. 1.9: utilisé comme bois d’oeuvre | Afzelia africana used as timber.
Au Bénin, le degré de pression sur Afzelia aicana varie en fonction
de la latitude et du statut de protection des stations. Entre 06°30 et
08° N : (essentiellement le groupe I) - Du côtier guinéen jusque
dans le zou (06°30 à 08°N) où l’on observe que Afzelia aicana à
l’état naturel, les pressions se résument essentiellement à l’exploi-
tation de l’espèce pour le bois d’œuvre. Ceci a déjà engendré dans
certaines localités du Sud du Bénin une forte rareté de l’espèce. Le
cas le plus illustratif est le Département du Mono (Kouo) où l’on a
noté une extrême rareté de l’espèce. Entre 08° et 11°45 N -(Essen-
tiellement les groupes II et III)- : La pression sur l’espèce est très
remarquable et est dans le plus grand nombre des cas occasionnée
par les éleveurs. Le pâturage aérien observé après le passage des feux
de saison sèche par des émondages répétés des arbres est la cause
fondamentale des mutilations subies par lespèce. Ensuite viennent
les exploitations pour la pharmacopée traditionnelle et pour le bois
d’œuvre.
... Afzelia africana is a multi-use tree species belonging to Fabaceae family (Angiosperm Phylogeny Group: APG III). Its crown can spread up to 35 m in height, with a diameter at breast height (DBH) measuring up to 1 m (Arbonnier 2000;Akoègninou et al. 2006;Assogbadjo et al. 2010). Flowering occurs at the end of dry season (April-May), fruiting in the middle of rainy season and fruits mature in December/January onward (Sacande 2007;Orwa et al. 2009). ...
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