Rainforests: The World's Green Lungs

A rainforest is a dense forest that receives more than 200 centimetres of rainfall every year. Most tropical rainforests grow near the equator, where it is hot and wet all year round. They cover only about 6% of the Earth's land, yet they are home to more than half of all the world's animal and plant species. That makes them the most crowded, lively habitats on the whole planet.

Rainforests are not all found in one place. As well as the giant Amazon in South America, there is the Congo Rainforest in Africa, and lush rainforests across South-East Asia and northern Australia. Wherever they grow, they share the same recipe: lots of warmth and lots of rain, all year round, with no cold winter to slow the plants down.

Rainforests grow in four distinct layers, each with its own community of plants and animals. The emergent layer at the top has the tallest trees poking above the rest. Below that is the canopy, a thick green roof where most animals live. The understorey is shady and damp, and the forest floor is almost completely dark. So little light reaches the floor that only about 2% of the sunlight ever touches the ground.

The forest floor is covered in fallen leaves and dead wood that decompose quickly in the warm, wet conditions. This keeps the soil full of nutrients that plants need to grow. Many medicines we use today were first discovered in rainforest plants, which is one more reason these places are so precious to people as well as to wildlife.

When huge areas of rainforest are cleared, a process called deforestation, the animals that live there lose their homes, and the carbon dioxide stored in the trees is released into the air, which warms the planet. Many people around the world are working to protect rainforests by replanting trees and helping local communities earn a living without cutting the forest down.