Old-Growth Forest

Old-growth forest is a term with different meanings. In every day use, old-growth forest usually implies an old forest, untouched by humans, with big trees. In this sense, old-growth is also referred to as virgin or ancient forest. For many people, forests of the Pacific Northwest are the prototype of old-growth forest. They contain large trees, big fallen logs, large standing snags and a multi-layered canopy .

For many scientists, old-growth forest refers to a forest in the later stages of ecological succession, not necessarily to a certain size or structure of trees. Old-growth forests are dominated by tree species that can regenerate in the shade created by the canopy of older trees. It is the ultimate or final stage in forest stand development, where processes and structures associated with gap dynamics (single-tree replacement) prevail over those associated with stand initiation from an earlier "catastrophic" disturbance. It need not be undisturbed by humans. The term "late-succesional forest" is also used.

Links:
U.S. Forest Service information page on old-growth forests

A collection of scientists' definition of old-growth forests and other forest types

Case Studies and Issues Involving Old-Growth Forest:
Plum Creek Land Exchange