Tropical Rainforest

Question 2

Features of a tropical rainforest?

Answer 2

• Tall, mostly evergreen trees (due to low seasonality)
• High rainfall
• High light levels -> increased primary productivity = more food energy to rich food web
• High temps
• Low seasonality

Question 3

What allows plants to grow all year, providing constant reliable food sources?

Answer 3

• High light levels
• High amounts of rainfall
• High temps

Question 4

What is the importance of rainforests?

Answer 4

• High biodiversity
• Resources
• Carbon sequestration
• Hydrological cycle
• Soil maintenance

Question 5

What are the benefits of high biodiversity in the rainforest?

Answer 5

• Estimated half of all terrestrial species live there and rainforests cover 10% of earths surface
• Increased chance of finding species useful to humans eg: new food species, medicine, biomimetics

Question 6

What resources can come from the rainforest?

Answer 6

• Timber -> house construction, tools
• Fibres -> cotton
• Resin, oil, wax -> rubber, palm oil
• Food -> chocolate from cacao, bushmeat
• Medicines -> Mexican wild yams produce diosgenin used for arthritis medication

Question 7

What is carbon sequestration?

Answer 7

• Plants absorb CO2 for photosynthesis
• Stored in woody tissues (if plant has any) and builds up a store of carbon
• reduces atmospheric CO2

Question 8

How is the rainforest important to the hydrological cycle?

Answer 8

• Important for downwind rainfall
• Over half rainfall in Amazon rainforest comes from transpiration elsewhere in the forest instead of evaporation from seawater

Question 9

How does the rainforest maintain soil?

Answer 9

• Warm, moist conditions = fast DOM decay = quick reabsorption of nutrients
• Because of this soils are shallow
• Vegetation cover protects from rain and roots bind soil together

Question 10

What are the threats to the rainforests?

Answer 10

• Deforestation
• Agricultural expansion
• Cattle grazing
• Mineral extraction
• Reservoirs
• Global climate change
• Exploitation of individual species
• Tourism

Question 11

What causes agricultural expansion?

Answer 11

• Farmers clear rainforests for agriculture due to fertile soils
• Continuous farming depletes biomass and soil fertility = more deforestation
• Habitats removed and soil quality reduced

Question 13

What are the effects of deforestation?

Answer 13

• Disrupts ecosystem due to habitat loss for species
• Habitat fragmentation -> isolated populations and increased edge effects

Question 14

What is the reason for deforestation?

Answer 14

• For fuel, timber -> construction, furniture
• Valuable hardwoods (teak, mahogany) targeted = long lasting damage
• Space for settlements and agriculture

Question 15

How does cattle grazing threaten the rainforest?

Answer 15

• Trees cleared for grazing land for cattle -> overgrazing, soil compaction
• Trees cleared for soy farms for soy based feeds
• All cause deforestation, decreased soil quality, habitat destruction