World Library  
Flag as Inappropriate
Email this Article

Periodic annual increment

Article Id: WHEBN0016473147
Reproduction Date:

Title: Periodic annual increment  
Author: World Heritage Encyclopedia
Language: English
Subject: Mean annual increment, Optimal rotation age, Index of forestry articles, Outline of forestry
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

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).[1] 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 instead 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).[2]

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

  1. ^ Avery, T.E.,B.E. Harold. 2002 Forest Measurements, fifth edition. New York: McGraw-Hill. 426 p.
  2. ^ Chapman, H.H.,1921, Forest Mensuration, second edition. New York: Wiley & Sons, Inc.


This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 



Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.