Acid rain is a result of air pollution. When any type of fuel is burnt, lots of different chemicals are produced.

Forests

Forests affected by Acid Rain

It is thought that acid rain causes trees to grow slower or even to die but scientists have found that the same amount of acid rain seems to have more effect in some areas than it does in others.

As acid rain falls on a forest it trickles through the leaves of the trees and runs down into the soil below. Some of it finds its way into streams and then into rivers and lakes. Some types of soil can help to neutralise the acid - they have what is called a "buffering capacity". Other soils are already slightly acidic so these are particularly susceptible to the effects of acid rain.

Acid rain can effect trees in several different ways, it may:

  • dissolve and wash away the nutrients and minerals in the soilwhich help the trees to grow such as potassium, calcium and magnesium
  • cause the release of harmful substances such as aluminium into the soil and waterways which further affects wildlife.
  • wear away the waxy protective coating of leaves, damaging themand preventing them from being able to photosynthesise properly.


A combination of these effects weakens the trees which means that they can be easily attacked by diseases and insects or injured by bad weather. It is not just trees that are affected by acid rain, other plants may also suffer.

Read More: Lakes and rivers

Related Resources