Tad’s right – old-growth roughly means ‘before humans first logged it.’ Some of those trees are over a millennium old.
Roy Underhill of The Woodwright’s Shop noted that the forests of early America seemed unquenchable, with many older trees that took two or three or more pairs of arms to encircle; now we’re lucky to find a 16” diameter cherry tree, ditto for walnut. The forests of eastern North America have been logged over 2x since European settlement, more or less, with a very few pristine areas in places like the Adirondacks and the Pisgah forests.
This is what caused the Brazilian tropical rainforest to get logged out, and it’ll be what gets swietenia mahoganies and diospyros ebonies on CITES 2…..if we don’t preserve them, they’ll die out and need to be protected so future generations will have them.