The quiet nature of trees hides the fact that trees are always working for us and for Earth. Trees give us goods to meet our basic needs. Trees are home to animals, insects, and birds. But their biggest and most important job is playing a role in making Earth and our environment healthy. Learn some of the ways trees help, why they are in danger, and what you can do to help protect them now. Book features: Table of Contents; Glossary; For More Information including books and web sites; Index; photos and captions; charts and graphs; source notes.