The importance of forests is summed by up this press release:
Forests cover one third of the earth’s land mass, performing vital functions and services around the world which make our planet alive with possibilities. In fact, 1.6 billion people depend on forests for their livelihoods. They play a key role in our battle against climate change, releasing oxygen into the atmosphere while storing carbon dioxide.
Forests feed our rivers and are essential to supplying the water for nearly 50% of our largest cities. They create and maintain soil fertility; they help to regulate the often devastating impact of storms, floods and fires.
Splendid and inspiring, forests are the most biologically diverse ecosystems on land, and are home to more than half of the terrestrial species of animals, plants and insects.
Forests also provide shelter, jobs, security and cultural relevance for forest-dependent populations. They are the green lungs of the earth, vital to the survival of people everywhere -- all seven billion of us.
The United Nations Environment Programme's World Environment Day website has links to events which have self-registered themselves online. One can also browse events geographically with an interactive map.