After a long walk in a neighborhood woods today, I understand less and less what we mean when we describe a tree or a forest as "old-growth." There are many definitions--some uninformed, some vernacular, some scientific, many political. And this is a problem when the definition is used to push timber sales through as in "we are not logging old-growth." Does this mean we (the Department of Natural Resources, Weyerhauser, whoever) is not cutting down certain really really big trees or that they are not logging in old-growth forests?
One sparrow does not a summer make. One really big tree does not an old-growth forest make. As we should expect, trying to define a state of a certain forest--one that has been growing, changing, living, dying, responding to natural forces for a thousand years (or more or less)--is not a simple matter. Old forests are complex and they don't translate easily into numbers or words.
Alaska used to have a slogan that attempted to define its undefinability: "Alaska is a state of mind." And old-growth forest is like this, too--a state of the forest. And that state takes in many qualities--large standing trees, large standing snags (dead trees with broken tops), fallen trees, nurse logs, nurse stumps, a broken canopy, trees of different age classes, certain understory plants. A forest featuring these qualities is one that has seen little human disturbance.