Unit 2 - The Environmental Importance of Forests


Lesson 8: Forests and the Air

Forests purify the air by removing air pollutants. Trees actually absorb harmful gases through the pores in the leaf surface.

Particles, such as dust, are trapped on the leaf surface and then washed to the ground during a rainfall.

This helps to reduce the amount of particles that we breathe in.

Forests play an important role in balancing the earth's CO2 supply and exchange, acting as a key link between the atmosphere, geosphere, and hydrosphere.


Trees are an important part of the carbon cycle; trees exchange large amounts of CO2 with the atmosphere and store carbon in trees and soils.
Some carbon goes right back into the atmosphere as the tree respires, but if the CO2 remains in the tree, it remains in the wood until the tree decomposes. Once it falls to the forest floor, it will be decomposed by bacteria and fungi and either be respired back into the atmosphere or made into soil carbon.
You can see how important trees are to ensure we have enough clean oxygen to breathe!

Think About It!

The pores in the leaves allow gas exchange to take place.  If the pores are clogged, the gas exchange would be reduced and affect the environment extensively.  Water vapor that evaporates from the plant would not be returned to the atmosphere, and this would disrupt the water cycle.  Plants absorb harmful gases and particles in the air through pores in their leaf surfaces.  This would reduce the quality of air that we breathe in significantly.