CARA'S TIPSVegetation: factors, succession & major types
JAMBWAECNECO
What the syllabus asks
JAMB: Physical Geography G: vegetation: factors, plant communities, succession, major types (tropical forest, savanna, desert, Mediterranean, temperate grassland and forest, coniferous, tundra, montane), human impact
WAEC: vegetation: factors affecting vegetation; plant communities and succession; major types of vegetation (world and West Africa); characteristics, distribution, uses; human impact and conservation
NECO: vegetation: factors affecting vegetation; plant communities and succession; major types of vegetation (world and West Africa); characteristics, distribution, uses; human impact and conservation
What you will learn
- Define natural vegetation and explain the factors affecting it.
- Explain plant communities and the stages of plant succession.
- Describe the characteristics, distribution and uses of tropical rain forest.
- Describe the characteristics and adaptations of savanna vegetation.
- Describe hot desert and montane vegetation.
- Describe the main temperate vegetation types.
- Describe and locate the vegetation belts of Nigeria and West Africa.
- Explain the relationship between climate, soil and vegetation.
- Explain the effects of human activities on vegetation.
- Describe methods of conserving vegetation.
Key points
- Natural vegetation grows without human interference.
- Factors: climate, soil (edaphic), relief, biotic (animals, people), fire.
- Succession: pioneer → herbs/grass → shrubs → trees → climax.
- Plagioclimax: succession held back by people, e.g. derived savanna.
- Rain forest: tall, evergreen, layered, many species, hardwoods, buttress roots, lianas, epiphytes.
- Savanna: grass with scattered trees; deciduous, xerophytic, pyrophytic; baobab, acacia, shea.
- Desert: xerophytes and ephemerals; oases.
- Montane: zones change with height (6.5 °C per 1,000 m).
- Temperate: Mediterranean, temperate grassland, deciduous, coniferous, tundra.
- Conifers are easier to exploit: pure stands, light softwood, snow transport.
- Nigeria: mangrove and freshwater swamp, rain forest, derived, Guinea, Sudan, Sahel; montane on plateaux.
- Mangroves: stilt roots, pneumatophores, halophytes, viviparous seeds.
- Climate, soil and vegetation are interdependent.
- Human impact: deforestation, burning, overgrazing, urbanisation, pollution.
- Conservation: reserves, afforestation, shelterbelts, controlled burning and grazing, alternative fuels, laws.
Start here: Natural vegetation and factors affecting it
Very little truly natural vegetation remains in densely settled countries like Nigeria; much of what we see is modified by farming, burning and grazing. Geographers still describe the natural type that would grow under the climate and soil.
Factors affecting vegetation
| Factor | How it works | Example |
|---|---|---|
| Climatic: rainfall | Amount, reliability and length of rainy season decide whether forest, grassland or desert plants grow | Forest where rain is heavy all or most of the year; grassland where there is a long dry season |
| Temperature | Warmth controls growth; frost and cold limit plants | Tundra mosses in cold lands; luxuriant tropical growth |
| Sunlight | Needed for photosynthesis; competition for light makes rain-forest trees tall | Emergent trees in rain forest |
| Wind | Dry winds increase transpiration; strong winds stunt trees | Harmattan drying effect in the savanna |
| Edaphic (soil) | Fertility, depth, drainage, salinity | Mangroves on salty swamp mud; grass on shallow laterite |
| Relief/topography | Altitude lowers temperature; aspect and slope affect water | Montane forest and grassland on the Obudu and Mambilla plateaux |
| Biotic: animals | Grazing and browsing; seed dispersal | Overgrazed land in the north |
| People | Clearing, burning, farming, planting | Derived savanna replacing forest |
| Fire | Repeated burning favours fire-resistant grasses and trees | Savanna maintained by dry-season fires |
Climate is usually the dominant factor at world scale, giving broad vegetation belts that roughly match the climate belts. Local factors (soil, relief, people) explain differences within a belt.
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Practice questions
- near the equator
- in mid-latitude interiors
- around the poles
- in hot deserts
Show answer
A: near the equator
Examples: Amazon, Congo Basin, south of Nigeria.
- grass with scattered trees
- short drought-resistant shrubs
- pure stands of one tree species
- trees in layers with a dense canopy
Show answer
D: trees in layers with a dense canopy
Buttress roots, lianas and evergreen trees are common.
- coniferous forest
- treeless tundra
- grassland with scattered trees
- dense evergreen forest
Show answer
C: grassland with scattered trees
It covers most of Nigeria.
- halophytes
- xerophytes
- hydrophytes
- epiphytes
Show answer
B: xerophytes
They have long roots, thick bark or small leaves.
- salty, waterlogged coastal swamps
- high mountains
- hot deserts
- cold polar regions
Show answer
A: salty, waterlogged coastal swamps
Stilt roots and breathing roots (pneumatophores) help them.
Key words
- Natural vegetation
- Plant cover that has developed without human interference.
- Plant community
- A group of plants of different species living together in an area and interacting.
- Succession
- The gradual, orderly replacement of one plant community by another until a climax is reached.
- Climax vegetation
- The stable final community in equilibrium with the climate and soil.
- Pioneer plants
- The first plants to colonise bare ground, e.g. lichens and mosses.
- Sere
- The whole sequence of stages in a succession.
- Edaphic factors
- Soil-related factors affecting plants.
- Biotic factors
- Influences of living things (animals and people) on vegetation.
- Xerophytes
- Plants adapted to dry conditions.
- Hydrophytes
- Plants adapted to growing in water or waterlogged soils.
- Halophytes
- Plants adapted to salty conditions, e.g. mangroves.
- Pyrophytes
- Plants adapted to survive fire, e.g. with thick bark.
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