Vegetation and Human Activities – Vegetation of Africa and the World (Senior 3 Geography) | Ganzaa

Vegetation of Africa and the World

Lessons

Senior 3 · Geography

Vegetation of Africa and the World

4 lessons

Lesson 4 of 4

Vegetation and Human Activities

25 min

Let's begin

A cork oak in southern Spain or Morocco can be stripped of its bark every nine years or so, for a century or more, without being cut down: the bark grows back, and the tree lives on. A hardwood tree in the Congo Basin, once felled, takes generations to replace. Both are uses of natural vegetation. The difference between them is the whole question of this lesson: how can people live from vegetation without destroying it?

How each vegetation type supports human activities

Vegetation	Main activities it supports	Main threat
Equatorial rainforest	Logging of hardwoods (mahogany, sapele, iroko); gathering of fruit, honey, medicines and rattan; plantation crops on cleared land (cocoa, oil palm, rubber); ecotourism	Clearing for farms, logging roads, mining
Savanna	Nomadic and settled herding of cattle, goats and camels; arable farming (maize, millet, cotton); wildlife tourism in game parks	Overgrazing, bush burning, poaching
Semi-desert	Nomadic pastoralism; gum arabic from acacias in Sudan and the Sahel	Overgrazing and fuelwood cutting, which spread the desert
Mediterranean	Olives, vines and citrus on cleared land; cork from cork oaks; grazing of sheep and goats	Summer wildfires, clearing for tourism and housing
Temperate grassland	Large-scale wheat and maize farming; cattle ranching	Ploughing out the natural grass, soil erosion by wind
Coniferous forest	Lumbering, pulp and paper; fur trapping	Clear-felling of large areas
Montane forest	Water supply for rivers and towns; tourism (gorilla and chimpanzee tracking); beekeeping in buffer zones	Clearing for farms on crowded hillsides

Definition

Deforestation: the permanent removal of forest so that the land is used for something else, such as farms, mines or towns. Desertification: the spread of desert-like conditions into dry lands, caused by droughts and by human misuse such as overgrazing. Example: parts of the Sahel.

How people change vegetation

Figure 5 links the main causes of deforestation to its effects.

Figure 5: deforestation, causes and effects.

Shifting cultivation (slash and burn): farmers cut and burn a patch of forest, grow crops for a few years until the soil is tired, then move on. With few people and long fallows the forest regrows; with more people the fallow is too short and the forest turns into scrub and grassland.
Overgrazing in the savanna and Sahel strips grass and bushes faster than they regrow. Bare soil is blown away, and desertification follows.
Bush burning clears old grass for fresh grazing, but repeated, hot fires kill young trees and turn woodland into open grassland.
Exotic species, planted for timber and fuel, replace natural vegetation; in Rwanda many hillsides now carry eucalyptus instead of montane forest.

Conserving vegetation

Protected areas: national parks and forest reserves, such as Rwanda's four parks (Lesson 3).
Afforestation and reforestation: planting trees on bare land, and replanting where forest was cut. Africa's Great Green Wall is a plan led by the African Union to restore a belt of land across the Sahel, from Senegal to Djibouti.
Agroforestry: growing trees among crops and on field edges, which holds soil, adds fodder and fruit and reduces the need to cut forest.
Sustainable harvesting: selective logging, felling quotas and replanting; harvests that leave the plant alive, such as cork and honey.
Less fuelwood: energy-saving stoves, biogas and gas for cooking.
Sharing benefits with neighbours: when people near a park earn from it, they have a reason to protect it. Rwanda reinvests 10 per cent of the tourism revenue of its national parks in the communities around them (RDB, 2026), as Figure 6 shows for Volcanoes National Park.

Figure 6: revenue-sharing allocations, 2026 (RDB).

BBC News: Why is Africa building a Great Green Wall? Watch for the cause of the problem (dry land losing its plant cover) and for the methods used to bring vegetation back.

Definition

Afforestation: planting trees where there was no forest before. Reforestation: replanting trees where forest has been cut. Agroforestry: growing trees and crops, or trees and livestock, on the same land. Example: grevillea trees along the edges of Rwandan farms.

Worked example

Worked example 1: reading Figure 6. What share of the 2026 allocation went to Musanze District?

Total: $495 + 659.8 + 659.8 + 164.95 = 1,979.55$ million francs, about Frw 1.98 billion, as RDB states.
Musanze's share: $\frac{659.8}{1{,}979.55} \times 100 \approx 33.3\%$
So about one third, the same as Nyabihu; Rubavu received about 8.3%.

Worked example

Worked example 2: why fallow length matters. A forest farmer clears a plot, farms it for 3 years and then leaves it to regrow. Explain what happens if the fallow is 20 years, and if it is 4 years.

With a 20-year fallow, trees regrow, their leaves rebuild the humus, and the soil recovers. The system is sustainable.
With a 4-year fallow, only grass and bushes have time to grow. The soil is cleared again before it recovers, so yields fall and the forest is replaced by scrub and grassland.
The difference is caused by population pressure: more people need the same land more often.

Warning

Planting trees is not the same as restoring forest. A plantation of one exotic species gives timber and fuel, but far less wildlife and water regulation than a natural forest. In an exam, distinguish afforestation with exotic trees from the restoration of natural vegetation.

Tip

Use, threat, solution. For any vegetation type, answer in three steps: what people use it for, how that use damages it, and how the use can be made sustainable. Give a named place for each.

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Practice

Define deforestation and desertification.
Name two economic activities supported by (a) savanna, (b) coniferous forest.
Give three effects of deforestation shown in Figure 5.
Explain how overgrazing can lead to desertification in the Sahel.
Using Figure 6, calculate how much more Musanze received than Burera in 2026.
Why is cork harvesting described as sustainable while clear-felling is not?
Explain why sharing tourism revenue with communities helps to conserve vegetation around a national park.
"Planting eucalyptus on every bare hill is the best way to protect Rwanda's environment." Evaluate this statement.

Show answersHide answers

Deforestation: the permanent removal of forest for another land use. Desertification: the spread of desert-like conditions into dry lands, through drought and human misuse such as overgrazing.
(a) Any two: herding of livestock; arable farming; wildlife tourism. (b) Lumbering; pulp and paper making (also fur trapping).
Any three: soil erosion and landslides; silting of rivers and lakes; loss of habitat and species; less rain recycled and a drier local climate; more CO₂ in the air; scarcer, dearer fuelwood.
Too many animals eat grass and shrubs faster than they regrow; the soil is left bare and is trampled; wind and rain then remove the topsoil, the ground holds less water and plants cannot re-establish, so the land becomes desert-like.
$659.8 - 495 = 164.8$ million francs.
Stripping cork leaves the tree alive and the bark regrows, so the same tree yields again for many decades; clear-felling removes every tree at once and leaves the soil bare.
People living next to the park gain schools, health care, water and jobs from it, so they have a reason to protect it rather than to clear it for farms, cut firewood or poach in it.
Trees on bare hills reduce erosion and supply fuel and timber, so planting helps. But eucalyptus is exotic, uses a lot of water and supports little wildlife, so it does not replace natural forest; other measures are also needed: protecting parks, restoring native forest (as at Gishwati), agroforestry with native or useful trees, and terracing. The statement goes too far.

1How each vegetation type supports human activities

2How people change vegetation

3Conserving vegetation

How each vegetation type supports human activities

How people change vegetation

Conserving vegetation