Home > Encyclopedia of Science > Ecology

• The subject matter of ecology
• Words to Know
• Energy and productivity
• The ultimate goal of ecology

Ecology is the study of the relationships of organisms with their living and nonliving environment. No organism exists entirely independently of other living and nonliving things around it. A cactus in the middle of the desert, for example, draws nourishment from the air and from the ground. It depends on sunlight for energy needed to grow. The cactus may be home to birds, lizards, and microscopic animals. Even relationships that seem to be stark and simple as that of the cactus with its surroundings involve complex ties that form the subject matter of ecology.

Ecological relationships are always reciprocal (shared) relationships. In the example of the cactus,...