CHAPTER I. The Forests of Western Africa

THE FORESTS OF WESTERN AFRICA

From a large scale-map of Africa, the various British West African Colonies and Protectorates, as well as Liberia, French Ivory Coast, the late German Colonies of Togo and Cameroons, can be seen on the western side of that Continent. In fact, these territories are all within the Tropics, and also between the latitudes of 13° North in the Gambia to nearly the Equator in the Cameroons, and between longitude of 17° West to 10° East. Roughly speaking, Upper Guinea, as this part is usually called, covers an area of 100 to 200 miles wide by a length of over 1,500 miles, as a sylvan belt mainly of one type of vegetation, which botanically, however, only begins to alter as the boundary of the Cameroons is approached in the eastern part of Nigeria. Therefore one finds several trees extending right through this area, and also an almost unbroken forest all the way along the coast line, and roughly 100 to 150 miles inland. The width of the forest varies rather according to the aspect of the coast line, because the prevalent wind being south- west, the greatest rainfall, and thus the heaviest type of forest, occurs when the coast line runs at right angles to the prevailing wind. This occurs, for instance, near Calabar, Nigeria in the Cameroons, part of the Gold Coast near Axim, and Sierra Leone near Freetown. In some instances this effect is accentuated by the proximity of mountains near the coast, as, for instance, north of Calabar and north of Benin. One tree, which might be taken as a type, is the Rhodesian Mahogany, Afzelia Africana, which is found right in this belt of forest on its northern side. As the name implies, it is also found in Rhodesia, near the Victoria Falls. Mahogany, Khaya Senegalensis, is another tree found in the Gambia, also in Nigeria right up to the Cameroon border, over 1,500 miles away.

However, in this huge forest belt there are great variations in the rainfall, from 20 to over 175 inches in the Oban Hills of Nigeria. There are also, naturally, variations in soil and elevation, which make differences in the character of the forest. The proximity to the sea causes yet another difference in the type of vegetation, combined as it often is with low elevation.

Broadly speaking, then, one can differentiate several distinct types of forest, though owing to slight changes in a locality the one merges into the other and very sharp boundary lines cannot be drawn.

I. The Mangrove Swamps are usually near the sea coast, though not always at the sea coast; a strip of Evergreen Forest is usually found actually on the sandy dunes of the sea coast. The Mangrove Swamps also extend up the rivers near the coast as a fringe a mile or more wide.

II. The Evergreen Forest is usually found on the sea coast, also extending inland up the rivers, and also on low land up to an elevation of a few hundred feet, as, for instance, the forest on the banks of the Calabar River.

III. The Freshwater Swamp Forests are also found in this type of locality.

IV. The Mixed intermediate Forest is found usually where the rainfall does not exceed 60 inches, or in slightly hilly country, and contains a few deciduous trees. Typical trees of this forest are the Triplochiton Nigericum and Mimusops multinervis. It contains both evergreen and deciduous trees.

V. The Fringing Forest, or “Gallerie” Forest of the Germans, is found at the edge of rivers or lakes, where the rainfall is otherwise too low for the mixed deciduous forests.

VI. The Savannah Forest, sometimes so-called Dry-zone Forest, usually occurs with a rainfall of 30 to 50 inches. The typical tree of this is the Lophira alata.

VII. The Evergreen Forest of the hills, chiefly above an altitude of 2,000 or 3,000 feet. It is especially noticeable on Mount Itakum and the Boji Hills (elevation 5,000 feet).

VIII. The Open Orchard Forest, with shrubby trees of small growth.

These, then, roughly follow the Œcological Divisions according to Warming, which are as follows:

Mangrove Swamp,

True Savannah,

Treeless Savannah, low and high grass,

Bush Savannah,

Tree Savannah,

Savannah Forest,

Sclerophyllus formations, such as

Bush and Forest,

Bamboo Forest.

Forests are in addition named after the locality, such as Benin Forests, Oban Forests, Ondo Forests. Again, yet another nomenclature is after the kind of tree represented, such as Evergreen Forest, where all the trees are evergreen all the year round; for instance, Calabar Forests, Ondo, South Benin.

The mixed forests and intermediate forests, where the trees are both evergreen and deciduous, growing side by side, such as Olokemeji Forests, Benin Forests, Obubra Forests, and Bende Forests. Thus summarising the Nigerian Forests, we get the following formations:

1. Nigerian Swamp Evergreen: Mangrove, type tree.

2. Evergreen Forests Lophira procera, Parinarium.

2a. Freshwater Swamp Forests Cynometra mitragyne.

3. Mixed Deciduous, intermediate Triplochiton, Iroko, Forests Chlorophora excelsa.

3a. Fringing Forests Mixed, deciduous really.

4. Canopied Deciduous Forests Olokemeji: Berlinia, Afzelia. (sometimes termed dense Savannah Forests)

5. Open Deciduous Forests Paradaniella Oliverii, Eugenia Owariensis, Terminalia Togoensis.

6. Tree Savannah Orchard Forest Lophira alata, Shea butter, Acacia; Iwu, Oyo, Ndeh.

7. Treeless Savannah Grass, a few stunted bushes of Acacia Isoberlinia, North Ogoja.