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Why are rainforests important on a global scale?
Like peat bogs on a much larger scale, tropical rainforests are massive carbon sinks that absorb carbon out of the atmosphere and release oxygen via photosynthesis. Tropical rainforests have absorbed 1/5 of all global fossil fuel emissions.
Why is interception high in tropical rainforests?
Because layered canopies of vegetation intercept rain as it falls, so only around 30% of the rainfall in the Amazon reaches the ocean.
What is convectional rainfall in the context of tropical rainforests?
Convectional rainfall refers to how the water that is intercepted by the canopies evaporates through the day, rises, condenses, and precipitates again. This is why rainforests have such heavy rainfall.
How are plants in the rainforest adapted to compete for the scarce resources?
Buttress roots are common on trees and plants in the rainforest; they help the plants absorb the most nutrients from the soil because they are shallow and spread over a wide area.
Drip-tip leaves are seen in 90% of plants in the rainforest, this is to prevent a buildup of water algae which would prevent the plants from photosynthesising.
Why are plants in the rainforest shallow-rooted?
Because the process of decay in the rainforest is extremely rapid thanks to hot and humid conditions where decomposers thrive, most new nutrients are found on the forest floor rather than in the soil.
What are the three ways that tropical rainforests release carbon?
Respiration
Decomposition
Human activity (Deforestation)
Why is the Amazon rainforest colloquially named ‘The lungs of the world’?
Because the Amazon rainforest is the world’s largest tropical rainforest, and the world’s largest carbon sink. In 2019, the Amazon stored 76 billion tons of carbon.
What are some of the major threats posed to the Amazon rainforest?
Deforestation
Illegal logging
‘Slash and burn’ agriculture
Hydroelectric dam construction
Mining operations
Infrastructure projects (eg train lines or motorways splitting the ecosystem)
What impact does deforestation have on the carbon cycle in tropical rainforests?
Less photosynthesis
Slash and burn fires to clear the forest release massive amounts of CO2
Lower rate of decomposition due to lack of moisture
All species dependent upon trees die or migrate, which releases more carbon by decomposition over a longer period of time
What impact does deforestation have on the water cycle in tropical rainforests?
Precipitation falls
Moisture reduces
Low interception; most rainwater reaches ground
High flood risk due to higher runoff
Less evapotranspiration due to lack of plants reduces rainfall - reduces the rainforest’s ability to recover
Positive human impacts on the Amazon rainforest include:
The majority of the Amazon now being protected by either national parks or reserves.
The FSC (Forest Stewardship Council) verifies tropical hardwood that is ethically and sustainably sourced.
Why are rainforests important to protect?
Because they are global carbon sinks that mitigate the enhanced greenhouse effect (climate change) and are diverse and unique ecosystems of species that cannot be found anywhere else on Earth.
How diverse is the Amazon rainforest?
The Amazon rainforest is extremely diverse, with over 300 tree species on average per hectare. In the UK, there are only 60 species native to the entire country, meaning that one hectare of land in the Amazon is 5 times more diverse in tree species than the entire UK.
What are some international approaches to rainforest protection?
Debt reduction programmes to free up government spending for environmental protection
International organisations / multilateral agreements to regulate logging (FSC)
What are some national approaches to rainforest protection?
Education
Reserves, National parks, and formal protection for rainforests
Monitoring activity with satellite technology
What are some local approaches to rainforest protection?
Afforestation
Shifting cultivation
Rubber tapping
Selective logging
Agroforestry (cultivating alongside existing vegetation)
Ecotourism
Why did the Amazonian drought of 2005 reverse decades of carbon capture?
Because tropical rainforests aren’t adapted to dry conditions, forest fires can release enormous amounts of carbon, as tree species do not typically encounter forest fires in the same way that they often do in mediterranean / temperate climates.
How much more carbon do tropical trees store each year?
Each year tropical trees store an extra 1.2 billion tons of carbon.
What will happen to rainforests if the enhanced greenhouse effect continues?
Rainforests will see less rainfall, leading to droughts like the 2005 Amazonian drought becoming commonplace. This causes mass death of plant and animal species, the breakdown of the rainforest ecosystem, and rainforests releasing enough CO2 into the atmosphere to become a net source of carbon.
What percentage of wood is carbon?
50%
What is the average rainfall in the Amazon Rainforest?
2,300 mm per year on average
In northwestern areas of the Amazon, annual rainfall can be as high as 6,000 mm or more.
¾ of Brazil’s total carbon emissions is a direct result of...
Deforestation of the Amazon
How much of the Amazon has been deforested?
1/5 of the Amazon has been destroyed. Between 2000 and 2007, an area the size of Greece was cleared from the rainforest.
How many trees are in the Amazon?
300 billion.
Name three international agreements / organisations that protect the Amazon.
TARAPOTO
ACTO
REDLACH (Watershed Management)
Name two major protected zones of the Amazon.
Tumucumaque National Park (3.8 million hectares)
Pará Rainforest Reserve (15 million hectares)
How is deforestation being mitigated / reversed in the Amazon?
Reforestation / afforestation
Enrichment of degraded forests with native species
What is the average temperature in a tropical rainforest?
27/28ºC
