W + C: Tropical Rainforest

Question 1

What are the main characteristics of a tropical rainforest?

Answer 1

• Annual rainfall 2000+mm & 27DC annually
• Home to 200m people and 50% all plant and animal species
• Rich biodiversity, Distinct layers
• Absorb huge quantities of CO2 and emit 28% of worlds oxygen

Question 2

Whats the water cycle in a tropical rainforest?

Answer 2

• High precip due to high humidity and unstable weather conditions in the tropics - rainfall occurs on most days
• Canopy intercepts up to 75% of rainfall
• Some drips to ground from leaves or flows as stem flow
• About 25% of rain evaporates, 75%, half used by plants and returned to the atmosphere by evapotranspiration, the other half infiltrates into the soil - either stored underground or flows overland to rivers and channels.

Question 3

What’s the impacts of humans on the tropical rainforests’ water cycle?

Answer 3

Deforestation:
- atmosphere becomes less humid
- More rain reaches ground - more compaction and overland flow as soil dries out when exposed to sun and not much transpiration
- Runoff increases
- Precipitation may be decreased (because evapotranspiration is decreased)

Question 4

What is the carbon cycle in Tropical rainforests?

Answer 4

• warm and wet conditions are ideal for plant growth - promotes photosynthesis, which absorbs a huge amount of CO2. also emits a great deal of oxygen
• Wood 50% C- TRFs are huge stores and sinks
• Respiration by plants and animals returns CO2 to the atmosphere
• Decompositions is active, decomposers thrive and release CO2 back into the atmosphere
• Some carbon may be stored in soil or dissolved and removed by streams

Question 5

What are the impacts of deforestation on the carbon cycle?

Answer 5

• Photosynthesis almost completely stops and plant/animals respiration becomes almost 0.
• rain washes ash into the ground (if TRF is burnt) increasing carbon content of soil
• Carbon runoff may increase and decomposers will largely be absent

Question 6

How can climate change impact tropical rainforests?

Answer 6

• increased number of droughts
• Extinction of some species - difficult to adapt to drier conditions
• Forest fires may increase
• Scientists predict that a 4% increase in temp could kill 85% of the Amazon rainforest

Question 7

What is the carbon in the Amazon?

Answer 7

• Est. to store 80 - 120 billion tonnes of carbon - a rising productivity due to sequestering of increased CO2 in the atmosphere.
• in 2015, suggested Amazon losing its capacity to absorb CO2. From a peak of 2b tonnes CO2 each year in 1990s, the net uptake has halved.
• Extra atmospheric CO2 naturally used by forest trees, they grow fast but die younger.

Question 8

What is the water in the Amazon?

Answer 8

• average discharge of water into Atlantic Ocean by the Amazon is 175,000 cubic m p/s - 15% of all the freshwater entering oceans each day
• Average rainfall is approx 2,300mm annually
• Up to 50% rainfall may never reach ground- intercepted by forest canopy and re evaporated into the atmosphere
• Of rainfall that’s evaporated back, 48% falls back as rain. Only 30% rainfall reaches the sea, as rest is in the constant closed system loop

Question 9

What are the drivers of change from the amazon?

Answer 9

• between 2000 - 2007 - an area of forest larger than Greece was destroyed
• Brazil is worlds 4th largest climate polluter, with 75% of their ghg emissions attributed to deforestation and land use change

Question 10

what is the vegetation change in the Amazon?

Answer 10

• climate change affects species sustainability, by directly altering conditions needed to grow and survive.

Question 11

What is the soil in the Amazon?

Answer 11

• Amazonian soils contain from 4-9kg of carbon in the upper 50cm of the soil layer.
• When forest are cleared and burned, 30-60% of the carbon is lost to the atmosphere.

Question 12

What are the rivers in the amazon?

Answer 12

• changes in precip, extreme rainfall events and seasonality may lead to: overall reduction in river discharge; flash flooding; destroy freshwater ecosystems; destroy water supply, which fulfils the needs of Amazonian people
• Warming water temp may; kill off temp dependant species; change the biodiversity of river systems by introducing new species and killing others; reduce water dissolved oxygen concentrations

Question 13

What are the attempts to limit human impacts on the Amazon?

Answer 13

• Selective logging - only some trees are felled, less damage and canopy is often left intact and can therefore regenerate
• Replanting - new trees to replace felled trees - Peru plans to restore 3.2m hectares of forest by 2020. important to replace with same type tree
• Environmental Laws - bans on excessive logging, laws that control land us, e.g. the Brazilian Forest Code states that landowners have to keep 50-80% of their land as forest
• Protection - setting up national parks and nature reserves. The Central Amazon Conservation Complex in Brazil set up in 2003 and protect biodiversity in a 49,000km2 area - local people allowed to use the area sustainably
• Within such areas, damaging activities such as logging/mining can be monitored and/or prevented.