- O&C Lands
- Public lands granted to the Oregon and California Railroad Company and subsequently revested to the United States.
- Old growth
- Old forests often containing several canopy layers, variety in tree sizes and species, trees at least 180 to 220 years old, and standing and dead woody material.
- Option 9 - (Also see NWFP)
- The option chosen in the decision on how to manage public forest lands within the range of the Northern Spotted OWL, and impliminated in June of 1994. It covers most federal lands west of the Casade Range to the Pacific Ocean in Washington, Oregon, and Northern California. This new plan divides the land up into seven management areas, each with their own set of rules. (See: Congressionally Reserved Areas, Late Successional Reserves, AMA's, Managed Late Successional Areas, Administratively Withdrawn Areas, Riparian Reserves, and Matrix.)
- Off-road vehicles, such as motorcycles, 4-wheel drive vehicles, and 4-wheelers.
- overmature timber
- Term used by the timber industry to describe old-growth trees. Also referred to as "decadent" timber.
- The upper canopy layer; the plants below comprise the understory.