How the forest works


Ten thousand years ago, about half the world' s land surface was covered with trees. Now, less than a third of the Earth' s terrestrial area (i.e. around 4 billion hectares) is forested. And this is shrinking fast: around the world, over 400,000 hectares of forest are cleared or degraded every week.

Trees are crucial to the welfare of our planet and play a vital part in controlling climate and water cycles. Their leaves absorb carbon dioxide - a gas given off by burning fuels such as wood, oil, and petrol, which contributes to climate change. The gas is then converted (or photosynthesized) into nourishing sugars which the growing tree uses and stores. This ability to soak up carbon dioxide and filter other pollutants means that trees help keep the air clean and reduce the risk of global warming.

Roots take up water, oxygen, minerals, and other nutrients from soil. They also anchor trees and bind soil, preventing it from being washed or blown away. As roots develop and spread out, spaces appear in the soil around them, aerating the earth and creat ing a sponge - like effect that allows the ground to soak up water, which is then gradually released into streams and rivers.

FORESTS:
TOO GOOD TO WASTE


Several images of the forest

Forests, however, do not only contain trees. They are made up of millions of plants, animals, and micro - organisms whose lives are all closely interlinked.

Termites, for example, break down fallen leaves and branches, releasing nutrients into forest soils and helping plants to grow. Some fungi provide tree roots with minerals and in turn the roots supply them with sugars. Fruit bats and birds distribute seed s so that new trees can grow. And different plants provide each other with suitable growing conditions: the Amazonian cupuacu flourishes in the shade of other trees while lianas rely on other plants to support them as they creep up towards the sunlight.



  • Different types of forest

  • The forest provides

  • Keeping the balance

  • The demands of the industrialized world

  • Biodiversity

  • Deforestation and people

  • The wider implications

  • Using forests wisely

  • The Future: Your Choice


  • Copyright 1996, The World Wide Fund For Nature