Tropical Rainforests

• What is the global distribution of rainforests? Use diagram and TEA (trend, evidence, anomaly)

  • Trend: Most located between tropical of cancer and tropical of Capricorn, close to equator
  • Evidence: South America, Congo
  • Anomaly: Some smaller patches of rainforest outside equator belt e.g. northeast Australia

  
• What is the general climate like in tropical rainforests?

  Hot and wet all year, with high rainfall (over 2000 mm annually) and consistent high temperatures (~26–28°C)

  
• What causes high rainfall in tropical rainforests?

  Warm air rises at the equator, cools and condenses to form heavy rainfall due to low pressure
• What are the four layers of the rainforest?

  Emergent, Canopy, Under Canopy, Forest Floor

  
• Describe the emergent layer

  Tallest trees (up to 70m), most sunlight, exposed to strong wind and rain, home to birds and monkeys

  
• Describe the canopy layer.

  Thick, continuous layer of trees (20–40m), intercepts most rainfall and sunlight, most biodiversity found here

  
• Describe the under canopy.

  Warm and humid, limited sunlight, home to saplings, sloths, jaguars, frogs, and climbing plants like lianas

  
• Describe the forest floor

  Dark, humid, little sunlight, rapid decomposition of dead plants and animals by fungi and insects (e.g., beetles)

  
• What is the name of rainforest soil?

  Latosol – a red, iron-rich soil
• Is rainforest soil fertile? Why/why not?

  • No, it is surprisingly infertile
  • Most nutrients are at the surface from decomposing leaf litter
  • Heavy rain causes leaching, washing nutrients away
• Why do rainforest trees have shallow roots?

  • Nutrients are only found at the surface;
  • Roots stay shallow to absorb them quickly before they are leached
• What is leaching and how does it affect soil?

  • Leaching is when heavy rainfall dissolves and removes nutrients from the soil, leaving it infertile and red in colour
• How does nutrient cycling help the rainforest survive on poor soil?

  Rapid decomposition of organic matter by fungi returns nutrients to the surface quickly, supporting fast plant growth
• Which layer of the rainforest receives the least amount of sunlight?

  Forest floor- dark with very little sunlight

  
• Which layer of the rainforest are most animal and bird life found?

  The Canopy Layer – it contains the most biodiversity and provides food and shelter

  
• What is an adaptation?

  When living things are adapted to their habitats- they have special features that help them to survive
• What are buttress roots and how do they help rainforest trees survive?

  • Buttress roots are large, wide roots that grow above the surface.
  • They support tall trees (20–40m) by increasing stability in shallow, nutrient-poor soil and help absorb nutrients and oxygen from the topsoil

  
• How do buttress roots relate to rainforest conditions?

  • The soil is thin and infertile, with nutrients near the surface. Buttress roots spread wide to absorb surface nutrients and anchor the tree in the soft, wet ground

  
• What are lianas and how do they adapt to rainforest conditions?

  • Lianas are vine-like plants that climb tree trunks to reach sunlight in the canopy.
  • They use trees for support, conserving energy and maximising light for photosynthesis

  
• How do drip-tip leaves help rainforest plants?

  • These are waxy leaves with pointed tips that let rainwater run off quickly, preventing fungal growth and damage from heavy rainfall.
  • The waxy surface also helps repel water
• How is the Draco lizard adapted to the rainforest?

  • It has wing-like flaps of skin that allow it to glide between trees.
  • This helps it escape predators and move through the dense canopy efficiently.

  
• How is the spider monkey adapted to rainforest life?

  • It has long, strong limbs and a prehensile tail that acts like a fifth limb.
  • This helps it swing and balance through the high branches of the canopy in search of food

  
• Why is biodiversity so high in tropical rainforests?

  • Due to stable climate, plentiful rainfall and sunlight, and a variety of ecological niches.
  • Constant conditions support complex food webs and nutrient cycling
• What is the Amazon Rainforest and where is it located?

  • The Amazon Rainforest is the largest and most well-known tropical rainforest in the world.
  • Located in South America, primarily in Brazil, but also spans across several other countries including Peru, Colombia, and Venezuela
• How large is the Amazon Rainforest?

  • It covers 40% of the South American continent and is approximately the same size as 10 million football pitches.
  • It is the largest tropical rainforest on Earth
• Why is the Amazon important for biodiversity?

  • The Amazon is home to 10% of all known plant and animal species on Earth, making it one of the most biodiverse ecosystems in the world
• Define biodiversity

  Biodiversity is the amount and variety of plant and animal life found in a particular habitat or on Earth as a whole
• What is deforestation?

  The chopping down of trees at a large scale
• Why is the Amazon Rainforest considered to be ‘at risk’?

  • Due to rapid and unsustainable deforestation
  • Threatens biodiversity, carbon storage etc
• Compare the rates of deforestation in the Amazon between 2018 and 2019- use TEA (Trend, Evidence, Anomaly)

  Trend: Deforestation rates were significantly higher in 2019 than in 2018

  Evidence: In July, deforestation peaked at over 850 sq miles in 2019, compared to under 300 sq miles in 2018

  Anomaly: In January and February, deforestation rates in 2018 and 2019 were similar and relatively low

  
• What are the main causes of deforestation in the Amazon?

  • Commercial Farming (65–75%) – Land is cleared for cattle ranching and large-scale plantations like palm oil and soy.

  • Subsistence Farming (5%) – Local tribes use “slash-and-burn” methods to grow crops.

  • Logging (3%) – High-value trees like mahogany are felled and sold.

  • Mineral Extraction (1–2%) – Land is cleared for gold and other minerals.

  • Energy Development (1–2%) – Dams for hydroelectric power (HEP) flood large areas.

  • Road Building (2%) – Roads like the Trans-Amazonian Highway (4000km long) open the rainforest to development
• What are the environmental impacts of deforestation?

  • Loss of biodiversity – 38 species a year, go extinct due to shrinking habitats.

  • Climate change – Less carbon dioxide is absorbed; burning releases CO2.

  • Soil erosion – Without trees, heavy rain washes away fertile soil, reducing plant growth
• What are the economic and social impacts of deforestation?

  • Improved economic development – Selling rainforest resources funds hospitals, roads, and schools
  • Infrastructure growth – More roads and airports improve transport and trade
  • Displacement of people: indigenous tribes lose their homes or are killed for land
• What is sustainability?

  Meeting the needs of the current population without compromising the ability of future generations to meet their own needs
• List reasons why the Amazon should be protected.

  • Biodiversity: Home to 50% of world’s species.

  • Climate Regulation: Stores CO2 and produces oxygen.

  • Water Cycle: Helps maintain rainfall patterns.

  • Indigenous People: Home to tribes and traditional ways of life.

  • Medicines: 25% of medicines come from rainforest plants, including anti-cancer properties.

  • Resources: Provides rubber, hardwoods, fruits, and nuts.
• What are examples of sustainable rainforest management?

  • Selective Logging & Replanting: Only mature trees are cut. Young ones left to grow. Logging licenses are required. Trees replanted.

  • Education: Locals taught about environmental impacts and better farming methods (e.g. Amazon Conservation Association).

  • International Agreements: FSC promotes sustainable wood. Rich countries restrict imports of illegally sourced wood.

  • Debt Reduction: Countries agree to write off debt in exchange for rainforest protection (e.g. 2010 USA-Brazil $21m debt-for-nature swap).

  • Conservation: Protected areas like ARPA (150 million acres in Brazil). Logging and industry are restricted.

  • Ecotourism: Small-scale tourism (e.g. Rio Blanco Project) provides income, protects the forest, and educates tourists