The Rainforest

Question 1

What are the rainforest tiers?

Answer 1

• Emergent layer at 30-40m with widely spaced trees.
• Main canopy lauer at 20-30m with densely packed trees.
• Under canopy of sapling trees about 15m high where light is available.
• Shrub layer is sparse and only in clearings.
• Ground layer of tree ferns only in clearings - full of dark-adapted plants.

Question 2

How is the rainforest adapted?

Answer 2

[See image]

Question 3

Is the rainforest seasonal?

Answer 3

• No, due to little variation in angle of sunlight at these latitudes.
• Means that trees are always in different stages of their development (e.g. some have flowers while others are losing leaves).

Question 4

Why are rainforest soils red?

Answer 4

Contain lots of iron near the surface.

Question 5

Describe the rainforest nutrient cycle.

Answer 5

1. Water and air percolates into soil and contacts rocks.
2. Tree growth means that roots contact rocks.
3. Rocky subsoil weathers and disintegrates over time to become topsoil.
4. Decaying vegetation/animals on top layer quickly become nutrients due to humidity.
5. Trees grow quickly in hot conditions and need nutrients more quickly. Take up via roots.

Question 6

Why does the deep soil have little nutrients?

Answer 6

• Nutrients are leached: taken down in solution and removed by rainwater.
• Nutrients have no time to percolate into subsoil layer due to hot climate > rapid takeup.

Question 7

Why is the biodiversity of the rainforest so great?

Answer 7

• Easy climate to adapt to.
• Large amount of variation means large amount of:
  
  • Habitats
  • Food

Question 8

Give examples of animals in the tropical rainforest.

Answer 8

1. Forest floor:
   
   1. Pygmy elephants
   2. Deer
   3. Rats
2. Canopy (80% of the species of the rainforest):
   
   1. Monkey
   2. Frogs
   3. Lizards

Question 9

Why is the rainforest valuable?

Answer 9

1. Soil erosion:
   
   • Roots increase soil stability
   • Trees increase interception, lessening impact of wind and rain on soil
   • Roots take up water from soil and reduce chance of mudflow and leaching
2. Water Quality:
   
   • Rainforests decrease leaching of soil into river.
   • Thus less sediment in river.
3. Soil Fertility:
   
   • Removing trees disrupsts the nutrient cycle.
   • Soil erosion also leads to soil infertility.
4. Atmosphere:
   
   • Act as a carbon sink (sequesters carbon dioxide).
   • Releases oxygen.
5. Medicine:
   
   • Contain many important medicines.
   • Many undiscovered.
6. Biodiversity:
   
   • Home for many species.
   • Most undiscovered.
   • Many endangered - could cause extinction if habitat removed.
7. Indigenous Peoples:
   
   • Provide a home for indigenous peoples.
   • History and culture.
8. Climate:
   
   • Transpiration increases rainfall. No transpiration risks drought.
   • Dark colour absobrs solar radiation - decrease heating of atmosphere.

Question 10

What are the threats to the rainforest?

Answer 10

1. Slash and burn farming (shifting agriculture is less of a threat if enough time for fallow)
2. Commercial logging
3. Plantations
4. Mining
5. Road-building - increasing access to previously inaccessible areas.
6. Population pressure (exacerbates everything + migration causes soil degradation) e.g. Indonesia

Question 11

How do you combat deforestation?

Answer 11

1. National Parks:
   
   • Wildlife and habitat will be protected.
   • However, difficult for park rangers to monitor large areas.
2. Selective logging:
   
   • Fell individual trees only when they are mature.
   • Means that the rainforest canopy is then preserved.
   • However, transportation of tree destroys other trees and roads open up area.
3. Debt-for-nature swaps:
   
   • Richer country cancels part of debt in return for other country paying for conservation activities.
4. Education and promotion of responsible management:
   
   • Includes Forest Stewardship Council NGO.
   • Approved companies show logo to show responsible management.
   • Reduces demand for non-responsible products.
   • Usually involves planting something like teak - valuable and fast growing.
   • However, reduces biodiversity and not fast-growing enough.
5. Ecotourism:
   
   • Provide walkways, information boards and centres.
   • Increases awareness.
   • Money from tourists funds local economy and conservation efforts.