Tropical Rainforest Ecosystem (OCR GCSE Geography A (Geographical Themes)): Revision Notes

2.2.1 Tropical Rainforest Ecosystem

Key Characteristics

• Tropical rainforest is a hot, wet ecosystem found on and near the Earth's equator.
• Contains far more species of plants and animals than any other biome.
• Covers approximately 6% of the Earth's surface.
• Receives about 2,000 mm of rain per year.
• Temperatures range from around 27 to 32°C.
• Conditions are wet and hot all year round, making it a good environment for growth.

Why is it Hot & Wet in a Rainforest?

• Sun's Rays
  • Shine directly on the land and sea at the equator, making it the hottest part of the Earth.
  • Heat warms the land, air, and sea, causing water to evaporate into the air.
• Warm Air
  • Can hold a lot of water.
  • As the air rises, it cools, and the water turns back into rain, creating clouds.
  • Results in a lot of rain in the forests around the tropics.

Structure of the Rainforest

Structure of the Rainforest

• The Emergent Layer
• The tallest layer, over 40 metres.
• Contains only a few tall trees which grow taller than the trees of the canopy.
• Plants are adapted for dry conditions with small, waxy leaves to prevent drying out.
• Canopy
• The second-highest layer, 30-45 metres.
• The canopy blocks out the sun from lower layers and intercepts (catches) rainfall.
• Contains the most plant species and animal species.
• Understory
• Low light conditions (2-15%).
• Plants adapted to low light grow here.
• Habitat for birds, butterflies, frogs, snakes, and lots of insects.
• Forest Floor
• Very little light (2%) reaches the forest floor, so plants grow slowly.
• The ground is covered in fallen leaves, rotting branches, and a network of shallow roots.
• Habitat for lots of insects.