(a) Draw an outline map of Nigeria. On the map, :how the annual distribution of rainfall (b) Highlight three effects of rainfall on the distribution of vege...

(a) Outline map of Nigeria showing annual rainfall distribution

Key: Annual rainfall generally decreases from the southern coast northwards. The Niger Delta and coastal belt receive over 2,000 mm; the southern interior receives 1,500 to 2,000 mm; the Middle Belt receives 1,000 to 1,500 mm; while the extreme north receives about 500 to 1,000 mm annually.

(b) Effects of rainfall on the distribution of vegetation in Nigeria

1. Heavy and almost continuous rainfall, especially over 2,000 mm in the south, supports dense tropical rain forest with tall trees. In the coastal swampy areas, it also supports mangrove vegetation.
2. Moderate rainfall of about 1,000 to 1,500 mm in the Middle Belt supports Guinea Savanna, made up of tall grasses and scattered trees.
3. Low and seasonal rainfall in the north supports Sudan and Sahel Savanna, where vegetation consists mainly of short grasses, thorny shrubs and widely spaced drought-resistant trees. Thus, vegetation becomes shorter, less dense and more open from south to north as rainfall decreases.

(c) Characteristics of the Guinea Savanna

1. It has tall grasses, often growing up to about 3 m high. The grasses are green in the rainy season and dry or brown in the dry season.
2. It has few scattered trees, with open grassland between them.
3. Many of the trees are deciduous and shed their leaves during the dry season; they commonly have thick bark and deep roots to withstand drought and bush fires.
4. Gallery forests occur along river valleys and streams where moisture is available throughout much of the year.