A forest is made up of groups of trees. Growing underneath these trees are shrubs, herbs, lower plants and microscopic organism in the soil. Forests provide some human needs such as fuel, wood for furniture, building and pulp, ropes and fibers, dyes, resins, medicinal plants and animals to eat and to keep as pets.
The vegetation in Nigeria is divided into two major types, namely Forest and Savannah. Each of these is sub-divided into zones. The forest types are divided into three zones, while the savannah types are divided into four zones.
Coastal forest and mangroves
This zone is found along coastal creeks, estuaries and lagoons. Different varieties of the red mangrove tree are common in this vegetation. However, in many areas, the coastal vegetation is now dominated by palm trees and lianas.
Deltaic swamp and moist lowland forest
This is a fresh water swamp forest zone. It occurs extensively in the flood plains of large rivers. This type of forest zone consists largely of slender trees. In some of the forest areas that have been disturbed, raffia palms have spread extensively and dominated the valley swamps. The moist lowland forest zone is now restricted to a few forest reserves in Ondo and Benin areas and in the Cross River basin along the Nigerian border with Cameroon. This high forest zone has been reduced to secondary forest as a result of human activities. Secondary forests contain mainly oil palm. The high forest zone is now made up of evergreen, water tolerant plants.
Forest – Savannah mosaic
The vegetation pattern of these areas is generally referred to as the “Derived Savannah”. In this zone, rural population densities and farming activities such as shifting cultivation and annual bush burning have all combined to degrade the original forest vegetation. The forest trees have been replaced by fire-tolerant savannah species. In some areas, only a few forest trees and grass savannah remain.
This is the largest vegetation zone in Nigeria. It covers the sparsely populated areas of the Middle Belt.
This describes the vegetation around Jos made up of leguminous wooded savannah e.g. Isoberlinaspp with Andropogon. This area has been affected by over-grazing, deforestation and fire. On the Mambilla Plateau, grasslands occur above 1450m on gentle slopes and forest communities are found along water courses and steep slopes.
The Sudan savannah vegetation consists of fairly closed savannah tree species and patches of grasses. The zone has a longer and more severe dry season than the Guinea savannah zone. The relative humidity is low. This mean annual rainfall is generally less than 1016mm. The grass is short, feathery, and gives continuous land cover, interspersed by short savannah trees such as Acacia spp. However, over-grazing and bush-burning have seriously depleted the grass cover in this zone.
The northern zone is mostly the Sahel Savannah. This zone has less than 500mm of rain annually and the dry season may be up to nine months long in the year. The total vegetation cover is therefore minimal. The trees are widely dispersed and usually have small throny leaves. The grass cover is generally very sparse. The main vegetation layer consists of low growing shrubs which, in some parts, form a dense bush. In eastern Borno, Kano and Jigawa states, sorghum grass dominates the grass layer.