Choose any two of the following vegetation types (a) Equatorial (b) Tropical continental (c) Tropical desert and for each (i) describe the vegetation charac...

Answer Details

Two vegetation types chosen: (a) Equatorial and (b) Tropical continental (savanna).

(a) Equatorial (tropical rain-forest) vegetation

(i) Vegetation characteristics:

• Tall, dense, evergreen forest arranged in three storeys (emergents, canopy, under-storey), with trees reaching 40 metres or more.
• Broad-leaved hardwoods (mahogany, iroko, ebony) with buttress roots; leaves have drip-tips.
• Great variety of species mixed together, with abundant lianas (climbers), epiphytes and a dark, bare forest floor.

(ii) How climate has influenced it: the constant high temperatures (about \(27^\circ C\)) and heavy, year-round rainfall (over \(2000\ mm\)) with no dry season allow continuous, rapid plant growth, so the forest stays green all year. Competition for light makes the trees grow tall in layers, the heavy rain produces drip-tips and buttress roots, and the warm damp conditions support a huge variety of species.

(b) Tropical continental (savanna) vegetation

(i) Vegetation characteristics:

• Tall, coarse grasses (often 1 to 3 metres) with scattered, short deciduous trees, giving a parkland appearance.
• Trees are drought- and fire-resistant, with thick bark, umbrella-shaped crowns, small leaves and deep roots (acacia, baobab, shea).
• Grass turns green in the wet season and dries brown in the dry season; trees become fewer and shorter towards the desert margin.

(ii) How climate has influenced it: the savanna has a marked wet and dry season. During the long dry season plants must survive drought, so trees shed their leaves, develop thick fire-resistant bark and long roots, and store water (baobab), while the grasses dry up and survive as roots and seeds. The seasonal, moderate rainfall (about \(750\ mm\) to \(1000\ mm\)) is enough for grass and scattered trees but not for continuous forest.