- Thousand board feet. Five thousand board feet of timber can be expressed as 5M board feet.
- Million board feet. (See Board feet.)
- Macro climate
- The general, large scale climate of a large area, as distinguished from the smaller scale micro climates within it.
- Managed Late-Succional Areas
- Option 9 land designation. These are similar to Late-Successional Reserves but are identified for certain endangered and rare plant locations, in other land designations, such as the matrix.
- Mass movement/wasting
- The down-slope movement of large masses of earth material by the force of gravity. Also called a landslide. Mass movements can be a result of clear cutting on unstable slopes.
- Where most deforestation is allowed to take place. An Option 9 land designation. Other examples of Option 9 land designations are LSR's, AMA's, and Riparian Reserves.
- Mature timber
- Trees that have attained full development, especially height, and are in full seed production. Sometimes called old-growth or late successional.
- Mean annual increment of growth
- The total increase in size or volume of individual trees. Or, it can refer to the increase in size and volume of a stand of trees at a particular age, divided by that age in years.
- Micro climate
- The climate of a small site. It may differ from the climate at large of the area due to aspect, tree cover (or the absence of tree cover), or exposure to winds.
- MIS (management indicator species)
- A wildlife species whose population will indicate the health of the ecosystem in which it lives and, consequently, the effects of forest management activities to that ecosystem. MIS species are selected by land management agencies. (See "indicator species".)
- Areas with a variety of plant communities over a landscape, such as areas with trees and areas without trees occurring over a landscape. Natural fires are often described to burn in a "mosaic" pattern.
- Multiple use management
- The management of all the various renewable surface resources of National Forest lands for a variety of purposes such as recreation, range, timber, wildlife and fish habitat, and watershed.