Periodic annual increment

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 Forest Measurements, fifth edition. New York: McGraw-Hill. 426 p. ] For sigmoid growth, the graph of PAI increases rapidly and then quickly declines, approaching zero. PAI may go negative if a tree loses volume due to damage or disease. Periodic annual increment is commonly used insted of current annual increment as a basis for computing growth "per cent". Growth "per cent" indicates the rate of increase with relation to the wood capital required for its production, this is usually based on a single year's growth (Chapman, 315). [ Chapman, H.H.,1921, Forest Mensuration, second edition. New York: Wiley & Sons, Inc.]

Equation

PAI= frac {Y_2-Y_1} {T_2-T_1}

Where: Y is the yield (volume, height, DBH, etc.) at times 1 and 2 and T1 represents the year starting the growth period, and T2 is the end year.

Example: Say that the growth period is from age 5 to age 10, and the yield (height of the tree), is 14 feet at the beginning of the period and 34 feet at the end. Then: frac {34-14} {10-5} = 4 feet/year

Uses

The maximum point on the curve of PAI is the same as the inflection point on a graph of yield versus time. The inflection point is the point corresponding to the fastest change in yield.

When mean annual increment (MAI) and periodic annual increment (PAI) are graphed together, the point in which they intersect is called the biological rotation age. The biological rotation age is the age in which a stand should be harvested to maximize long-term yield.

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • 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… …   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

  • 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

  • ECONOMIC AFFAIRS — THE PRE MANDATE (LATE OTTOMAN) PERIOD Geography and Borders In September 1923 a new political entity was formally recognized by the international community. Palestine, or Ereẓ Israel as Jews have continued to refer to it for 2,000 years,… …   Encyclopedia of Judaism

  • LABOR — Jewish Labor Organizations IN THE PRE STATE PERIOD Since the last decades of the 19th century, a number of sporadic labor associations have arisen in agriculture and in the printing, clothing, and building trades, as well as groups limited to a… …   Encyclopedia of Judaism

  • California Proposition 13 (1978) — Elections in California …   Wikipedia

  • chemical element — Introduction also called  element,         any substance that cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which all matter is composed.       This article considers the… …   Universalium

  • accounting — /euh kown ting/, n. 1. the theory and system of setting up, maintaining, and auditing the books of a firm; art of analyzing the financial position and operating results of a business house from a study of its sales, purchases, overhead, etc.… …   Universalium

  • Exact sciences (The) in Hellenistic times: texts and issues — The exact sciences in Hellenistic times: Texts and issues1 Alan C.Bowen Modern scholars often rely on the history of Greco Latin science2 as a backdrop and support for interpreting past philosophical thought. Their warrant is the practice… …   History of philosophy


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.