tropical rainforests

What is the climate of the TRF? What about the rainfall?

Little seasonal variation. It’s hot because it is within 23.5º of the equator. There is conventional rainfall - warm air rises as the sun heats the ground, which cools as it rises and forms large cumulonimbus clouds. These result in heavy rain.

What is the soil in the TRF like?

Infertile as lots of leaching, washing away nutrients. Leaf litter provides nutrients however hot, damp conditions means fast decay.

What plants live in the TRF and what adaptations do they have?

Most trees are evergreen due to the continual growing season and have buttress roots to support them. Plants have drip-tips to allow heavy rain to run off the leaves, preventing algae. Many trees have smooth, thin bark so water can run off. Lianas climb to reach sunlight.

EXAMPLES: orchids, bamboo, mahogany / banana trees

What animals live in the TRF and what adaptations do they have?

Rainforests contain 50% of the Earth’s species. Many animals live in the canopy, with strong limbs to swing from tree to tree. Some animals have flaps of skin to fly between trees (e.g. flying squirrels). Some animals camouflage to hide from predators. Most birds have short, pointy wings to easily move between dense tree branches.

EXAMPLES: gorillas, jaguars, anacondas, tree frogs, sloths

What are the four layers of the rainforest?

Emergent (top)

Canopy

Under canopy

Shrub layer (bottom)

What are the six main causes of deforestation?

• Population pressure: as population increases, trees are cleared to make land for new settlements

• Mineral extraction: minerals (e.g. gold and iron) are mined and sold for money

• Energy development: building HEP dams floods large areas of forest

• Commercial logging: trees felled to make money

• Commercial farming: cattle grazing, and huge palm / soya plantations

• Subsistence farming: farmers clear land to grow food for themselves + families

How is the rate of deforestation changing?

It’s very high but globally the rate is slowing; however there are hotspots of increase (e.g. Nigeria).

Case study: deforestation in the Amazon

• The Amazon the largest TRF in the world but since 1978 has over lost over 750000km² to deforestation

MAIN CAUSES

• About 70% by cattle ranching / commercial farming

• 20-25% by subsistence farming

• Population growth also putting pressure on the Amazon rainforest, especially in Brazil

MAIN IMPACTS

• Environmental: the Amazon stores around 100 billion tonnes of carbon and deforestation releases this, causing global warming. Brazil is losing 55 million tonnes of topsoil yearly due to soil erosion caused by soy farming.

• Economic: in 2008, Brazil made $7 billion from trading cattle. The mining industry creates jobs for people. Logging contributes to a huge amount of Brazil’s economy.

Why does the tropical rainforest need protecting?

• 25% of all medicines come from rainforests

• Many products (e.g. rubber, coffee, chocolate) sourced here

• They are carbon sinks (absorb large amounts of carbon dioxide which regulates the global climate)

How can rainforests be sustainably managed?

• Selective Logging: only some trees (e.g. older ones) are felled, keeping the overall forest structure and allowing for regeneration

• Replanting: new (same type of) trees are planted to replace the ones that are cut down

• Ecotourism: only a small amounts of visitors can tour at one time with strict rules in place. Tourism gives locals legal jobs.

• International Hardwood Agreements: in place to reduce illegal logging of hardwood (mahogany, teak, etc) for furniture

• Education: educating locals about the impacts of logging and giving alternative ways for them to make money

• Reducing Debt: LICs don’t have to log, farm and mine to pay back debt

• Conservation: countries pay into protected national parks and nature reserves in rainforests