Tropical rainforests – layers, nutrient cycle and deforestation
GeographySoils, Biosphere & EnvironmentAges 11–12
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Sign in to playA cross-section of a tropical rainforest with emergent, canopy, understorey, shrub and forest-floor layers and their adaptations, and a Gersmehl nutrient-cycle diagram (biomass, litter, soil). Set logging, cattle ranching, soy, oil palm, mining and road building, watch forest cover, biodiversity, carbon, soil nutrients and rainfall change on a land-use map over 50 years, then test sustainable management.
Lesson: Tropical rainforests: structure, adaptations, nutrient cycling, causes and impacts of deforestation, sustainable management
What it shows
Tropical rainforests grow in layers: scattered emergent trees, a closed canopy, a dim understorey and a forest floor that gets about 2% of the sunlight, each with its own adaptations. The Gersmehl model shows why the soils are poor: most nutrients are stored in the biomass and recycled fast. In this model of a 160 km × 100 km region, logging, cattle ranching, soy, oil palm, mining and new roads clear the forest, releasing carbon, reducing biodiversity and rainfall and exhausting the soil. Reserves, selective logging, ecotourism, certification, debt-for-nature swaps and REDD+ can slow the loss.
How to use
Use Forest layers to see the cross-section and tap a layer for its adaptations, or Nutrient cycle for the Gersmehl diagram; Compare adds a temperate deciduous forest. Set Logging, Cattle ranching, Soy, Oil palm, Mining and Road building, then press Run or +1 year. Try Reserve and the management boxes, tap a map cell to inspect it, and press Add to table to compare runs.
Parameters you can change
- Logging 0–500 km²/year
- Clearing for cattle ranching 0–500 km²/year
- Clearing for soy 0–300 km²/year
- Clearing for oil palm 0–300 km²/year
- Mining 0–100 km²/year
- New roads 0–50 km/year
- Protected reserve 0–50 % of the region
- Selective logging (instead of conventional logging)
- Ecotourism in the reserve
- Certification: soy and oil palm only on land already cleared
- Debt-for-nature swap (15% more reserve, enforced)
- REDD+ (payments to keep forest, clearing halved)
- Panel next to the map Forest layers cross-section, Nutrient cycle
- Compare nutrient cycle None, Temperate deciduous forest
Questions to explore
- Why does pasture on former rainforest land often lose its fertility within a few years?
- How do new roads change where and how fast the forest is cleared?
- Which mix of management keeps the most forest while still giving the region an income?
