﻿

# Mean annual increment

The mean annual increment (MAI) or mean annual growth refers to the average growth per year a tree or stand of trees has exhibited/experienced to a specified age. For example, a 20-year old tree that has a diameter at breast height (dbh) of 10.0 inches has an MAI of 0.5 inches/year. MAI is calculated as MAI = Y(t) / t where Y(t) = yield at time t. Because the typical growth patterns of most trees is sigmoidal, the MAI starts out small, increases to a maximum value as the tree matures, then declines slowly over the remainder of the tree's life. Throughout this, the MAI always remains positive. MAI differs from periodic annual increment (PAI) because the PAI is simply the growth for one specific year or any other specified length of time.

MAI vs PAI

The point where the MAI and PAI meet is typically referred to as the biological rotation age. This is the age at which the tree or stand would be harvested if the management objective is to maximize long-term yield. The proof of this definition is shown by differentiating MAI(t) with respect to t, and is shown by Husch, Miller, and Beers [1]

## References

1. ^ Husch, B., Miller, C.I., and T.W. Beers. 1982. Forest Mensuration. Wiley. New York. 402 p.

Mean Annual Increment

Avery and Burkhart. Forest Measurements. Fifth Edition, McGraw Hill, New York. 2002.

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Periodic annual increment — (PAI), is a forestry term that describes the change in the size of a tree between the beginning and ending of a growth period, divided by the number of years that was designated as the growing period (Avery, 339). [ Avery, T.E.,B.E. Harold. 2002… …   Wikipedia

• Outline of forestry — See also: Index of forestry articles The following outline is provided as an overview of and guide to forestry: Forestry – the art and science of managing forests, tree plantations, and related natural resources. Forest ecosystems have come to be …   Wikipedia

• Optimal rotation age — Contents 1 Economically optimum rotation age 2 Biologically optimum rotation age 3 Non timber forest use and effect on rotation 4 Factors …   Wikipedia

• Mai — may refer to: Contents 1 Given name 2 Surname 3 Fictional characters 4 Other uses 5 Acronym …   Wikipedia

• MAI — • Machine Aided Indexing • Manufacturer Access Interface • Mean Annual Increment • Multiple Address Instruction • Modell Access Interface ( > Bauch/Zemmit: Kommunikation produktdefinierender Daten im ISDN B , ISM TUB ) • Mangochi, Malawi… …   Acronyms

• MAI — [1] Machine Aided Indexing [2] Manufacturer Access Interface [3] Mean Annual Increment [4] Multiple Address Instruction [5] Modell Access Interface ( > Bauch/Zemmit: Kommunikation produktdefinierender Daten im ISDN B , ISM TUB ) [6] Mangochi,… …   Acronyms von A bis Z

• river — river1 riverless, adj. riverlike, adj. /riv euhr/, n. 1. a natural stream of water of fairly large size flowing in a definite course or channel or series of diverging and converging channels. 2. a similar stream of something other than water: a… …   Universalium

• permafrost — /perr meuh frawst , frost /, n. (in arctic or subarctic regions) perennially frozen subsoil. Also called pergelisol. [1943; PERMA(NENT) + FROST] * * * Perennially frozen earth, with a temperature below 32 °F (0 °C) continuously for two years or… …   Universalium

• France — • Geography, statistics, and history Catholic Encyclopedia. Kevin Knight. 2006. France     France     † …   Catholic encyclopedia

• Taiwan — /tuy wahn /, n. Wade Giles, Pinyin. a Chinese island separated from the SE coast of China by Taiwan Strait: a possession of Japan 1895 1945; restored to China 1945; seat of the Republic of China since 1949. Cap.: Taipei. Also called Formosa. * *… …   Universalium