Book excerpt: Forest ecology includes within its scope the components and functions of forest ecosystems -- a community of organisms interacting with each other and with their physical environment. Forest ecosystems, which consist of bacteria, plants, birds, mammals, reptiles, amphibians, soil, water and air, differ from other ecosystems in that they are dominated by trees and other woody vegetation. Each of these components plays an important role in the function and health of the forest. This book presents important research in the field.