Eduqas A-Level Geography A110QS
Coastal LandscapesLandscape
Glaciated LandscapesLandscape
Changing Places
Water and Carbon Cycles
Global Migration
Global Governance of the Oceans
Tectonic Hazards
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
Geographical Skills
Ecosystems
Nutrient cycling and the Gersmehl model
- 3 things to know
- Component 3 Section B
Overview
Nutrient cycle, three stores in the Gersmehl model and transfers between the stores in the Gersmehl model.
What you need to know
Answer each one before you reveal it.
Name the three stores in the Gersmehl model.
Name the transfers between the stores in the Gersmehl model.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is a nutrient cycle?
Model answer
A nutrient cycle is the circulation of mineral elements between the living and non-living parts of an ecosystem. Nitrogen, phosphorus, potassium and calcium are the main nutrients involved.
- 2
Name the three stores in the Gersmehl model.
Model answer
Biomass, litter and soil are the three stores. Circle size in the model is proportional to the amount held in each.
- 3
Name the transfers between the stores in the Gersmehl model.
Model answer
Litter fall moves nutrients from biomass to litter, and decay moves them from litter to soil. Uptake by roots returns nutrients from the soil to the biomass.
- 4
Name the inputs and outputs in the Gersmehl model.
Model answer
Precipitation adds nutrients from the atmosphere, and weathering of parent rock adds them from below. Losses occur through surface runoff from the litter and leaching from the soil.
- 5
What is leaching?
Model answer
Leaching is the removal of soluble nutrients as water percolates down through the soil. Heavy rainfall in the tropics makes leaching rapid.
- 6
What is litter fall?
Model answer
Litter fall is the transfer of dead leaves, branches and animal remains from the biomass to the ground surface. The rate depends on the type of vegetation and on the season.
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