WJEC A-Level Geography 601-8455-3
Coastal Landscapes
Glaciated Landscapes
Tectonic Hazards
Changing Places
Water and Carbon Cycles
Global Migration
Global Governance of the Oceans
EcosystemsContemporary theme
Economic Growth and Challenge: IndiaContemporary theme
Economic Growth and Challenge: ChinaContemporary theme
Development in an African ContextContemporary theme
Energy Challenges and DilemmasContemporary theme
Weather and ClimateContemporary theme
Fieldwork and Geographical Skills
Ecosystems
Nutrient cycling in contrasting biomes
- 3 things to know
- A2 Unit 4
Overview
Three stores in the Gersmehl model of nutrient cycling, transfers in the Gersmehl model and relative store sizes in a tropical rainforest.
What you need to know
Answer each one before you reveal it.
Name the transfers in the Gersmehl model.
Describe the relative store sizes in a tropical rainforest.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Name the three stores in the Gersmehl model of nutrient cycling.
Model answer
Biomass, litter and soil.
- 2
Name the transfers in the Gersmehl model.
Model answer
Fallout from biomass to litter, decay from litter to soil, and uptake from soil to biomass, with inputs from weathering and precipitation and losses by leaching and run-off.
- 3
Describe the relative store sizes in a tropical rainforest.
Model answer
Biomass is by far the largest store, litter is small because decay is rapid, and soil is small because nutrients are taken up almost immediately.
- 4
Explain why rainforest soils are nutrient-poor despite the luxuriant vegetation.
Model answer
Warmth and moisture make decomposition very fast, plants absorb the released nutrients at once, and heavy rainfall leaches whatever is not taken up.
- 5
What happens to nutrient cycling when a rainforest is cleared?
Model answer
The main store is removed with the trees, the exposed soil is leached and eroded by heavy rain, and fertility collapses within a few growing seasons.
- 6
Describe the relative store sizes in a boreal forest.
Model answer
Litter is the largest store because cold slows decomposition, biomass is substantial but slow-growing, and the soil store is small and acidic.
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