Tree allometry: Difference between revisions

Revision as of 03:42, 25 September 2010

Revision as of 23:25, 20 October 2010

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{{Expert-subject-multiple|Forestry|Ecology|date=March 2008}}

{{Wikify | date = October 2010}}

[[File:Profil_du_tronc.png|thumb|'''Stem profile measurement''' Electronic equipment is used for stem profile measurements and for measurements of profiles/projections of the crown. These key measurements are used for estimation of carbon sequestered in the plants.]]

[[File:Structureforet.jpg|thumb|right|Forest structure measurement is needed for establisment of allometric equations.]]

'''Tree allometry''' establishes quantitative relations between some key characteristic dimensions of [[tree]]s (usually fairly easy to measure) and other properties (often more difficult to assess). To the extent these statistical relations, established on the basis of detailed measurements on a small sample of typical trees, hold for other individuals, they permit extrapolations and estimations of a host of [[dendrometry|dendrometric]] quantities on the basis of a single (or at most a few) measurements.

The study of [[allometry]] is extremely important in dealing with measurements and data analysis in the practice of forestry. [[Allometry]] studies the relative size of organs or parts of organisms. Tree allometry narrows the definition to applications involving measurements of the growth or size of trees. Allometric relationships are often estimating difficult tree measurement, such as volume, from an easily-measured attribute such as [[diameter at breast height]] (DBH).

The use of [[allometry]] is widespread in [[forestry]] and [[forest ecology]]. In order to develop an allometric relationship there must be a strong relationship and an ability to quantify this relationship between the parts of the subject measured and the other quantities of interest.<ref>Smith, W.B., and G.J. Brand. 1983 Allometric biomass equations for 98 species of herbs, shrubs, and small trees. Research note NC-299. USDA Forest Service, North Central Forest Experiment Station, St. Paul, MN 8p.</ref> Also when developing this equation one must play in factors which affect tree growth such as age, species, site ___location, etc.<ref>Avery and Burkhart. Forest Measurements. Copyright 2002 by McGraw-Hill Companies Inc. New York.</ref> Once all these guidelines are met, one may attempt to develop an allometric equation.

First thing to do is select a group of some subject (for forestry: trees). Then measure several easily measured attributes such as DBH, height, species, etc. Graph the results and perform a regression analysis and transform some of the variables until a correct [[Regression analysis|regression]] is found.

<!-- Image with unknown copyright status removed: [[Image:Regressiongraph.jpg|thumb|right|300px|Allometric relationship of Volume Vs. Height*DBH² for an Appalachian oak stand]] -->

There are different tree species compositions in each region in the world and most of those regions have at least one equation that estimates tree volume from DBH. Research and the application of forest allometry have meshed over time to develop these quick equations to accurately estimate how much volume a particular forest stand holds.

The general allometric equation for mathematics and science is

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A well-known allometric equation relates metabolic rate to body mass: Y = βM 3/4.

In [[forestry]] the equation takes on many forms in order to represent relationships between the many various attributes of tree size and growth. Below is an example:

''Y = b₀ + b₁ X''