ZIMSEC A Level · Geography · Form 5, Form 6
Ecosystem functioning
Energy flows through trophic levels; nutrients cycle between biomass, litter and soil (Gersmehl's model). Net primary productivity is high in tropical rainforests and moderate in savanna.
Soils
Soil profiles show horizons (O, A, B, C). Processes: leaching, podzolisation, laterisation (in hot, wet climates: iron and aluminium oxides concentrate, forming red ferralitic soils), and calcification in dry areas. Catenas show how soils change down a slope.
The savanna biome
- Climate: wet and dry seasons; rainfall about 500–1 500 mm.
- Vegetation: grasses with scattered trees (miombo with msasa; mopane in hot, dry valleys; baobabs); adaptations to drought and fire.
- Factors maintaining savanna: climate, fire, grazing (wildlife and livestock), soils and human activity.
Human impact
Deforestation for firewood and tobacco curing, overgrazing, veld fires, and desertification in marginal areas. Conservation: national parks (Hwange, Gonarezhou), community schemes such as CAMPFIRE, afforestation, and sustainable land management.
Biodiversity
Zimbabwe's wildlife is a major tourism asset; threats include poaching, habitat loss and human–wildlife conflict.
Check yourself
- What is laterisation?
- Give two factors that help maintain savanna vegetation.
- Explain the aim of CAMPFIRE.
Show answers
- A soil-forming process in hot, wet climates where silica is leached and iron and aluminium oxides concentrate.
- Any two: seasonal rainfall, fire, grazing, poor soils, human activity.
- To let rural communities benefit from wildlife (e.g. through tourism and hunting revenue) so they manage and conserve it.
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