Vegetation in Rwanda
Senior 2 · Geography and Environment
Vegetation in Rwanda
Lesson 2 of 3
18 min
Nyungwe and Bugesera are only about 100 km apart, yet one is covered by rainforest and the other by grass and thicket. Understanding why tells you what each area can support. It helps you judge where to plant trees, which land to protect, and what happens when people change the land. Examiners often ask you to "account for" the distribution of a vegetation type. This lesson gives you the factors to use.
Plants need water and warmth. Where rain is heavy and falls in most months, as on the Congo–Nile Ridge (often above 1,500 mm a year), trees can grow tall and stay green: forest. Where rain is lower and the dry season is long, as in the eastern lowlands (often under 1,000 mm), only plants that survive drought do well: savanna.
Temperature falls by about 6.5 °C for every 1,000 m you climb. On a high mountain, the vegetation therefore changes in belts (zones), one above the other. This is called altitudinal zonation.
A climber walks up Karisimbi from about 2,400 m to the summit at 4,507 m. Describe the vegetation she passes through and explain the change.
| Height (approximate) | Vegetation |
|---|---|
| Below about 2,400 m | Lower montane forest, now mostly cleared for farms |
| About 2,500–3,200 m | Bamboo forest |
| About 2,600–3,600 m | Hagenia–Hypericum woodland: twisted, moss-covered trees on the wetter slopes |
| About 3,500–4,200 m | Afro-alpine plants: giant lobelias and giant groundsels |
| About 4,300–4,500 m | Short grassland near the summit |
The bands overlap because slopes differ in rainfall and soil. Explanation: over the 2,107 m climb, the temperature falls by about 2,107 × 6.5 ÷ 1,000 ≈ 13.7 °C. The higher zones are too cold, with frost at night, for tall forest, so the plants get smaller and tougher with height.
Grazing and browsing animals shape vegetation. Buffalo, zebra and giraffes feed on grass and young trees in Akagera, helping to keep the savanna open. Termites and earthworms mix the soil.
Dry-season grass fires kill young trees but not deep-rooted grasses, so repeated burning keeps land as savanna. People now have the strongest influence of all. They clear forest for farms and settlements, graze cattle, drain swamps and plant exotic trees. They also protect some areas as national parks.
Tip
Memory hook: "CARSOH". Climate, Altitude, Relief, Soils and drainage, Organisms, Humans (and fire). For every factor, write the cause and the vegetation that results. For example: "heavy, reliable rainfall on the Congo–Nile Ridge → evergreen rainforest in Nyungwe."
Solution: lower rainfall with a long dry season, and grass fires (plus grazing animals) that stop trees from taking over.
Solution: the change of vegetation in belts with height on a mountain, caused mainly by falling temperature.
Solution: fall = 1,400 × 6.5 ÷ 1,000 = 9.1 °C, so 18 − 9.1 = 8.9 °C.
Solution: the valley floor is waterlogged and papyrus is adapted to wet soil; the ridges are well drained and dry out.
Solution: the bamboo zone.
Summary
Sources and credits
The factor explanations, the lapse-rate worked example and the practice items are written by Ganzaa.
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
