# Tree taper

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'''Tree taper''' is the degree to which a tree's stem or bole decreases in diameter as a function of height above ground. Within Forestry and for the purposes of timber production, trees with a high degree of taper are said to have poor form, while those with low taper have good form. The opposite is the case for open-grown amenity trees. The form of a tree is sometimes quantified by the [Girard form class](/source/Girard_form_class), which is the ratio, expressed as a percentage, of the butt-log [scaling diameter](/source/scaling_diameter) to [diameter at breast height](/source/diameter_at_breast_height).<ref>Mesavage, C., and J.W. Girard. 1946. Tables for estimating board foot volume of timber. Department of Agriculture, [Forest Service](/source/United_States_Forest_Service), Washington, DC. 94 pp.</ref>

Taper is often represented by mathematical functions fitted to empirical data, called [taper equations](/source/taper_equations). One such function, attributed to Ormerod,<ref>Ormerod, D.W., 1973. A simple bole model. ''[Forestry Chronicle](/source/Forestry_Chronicle)''. 49:136-138.</ref> is

right|Tree taper equation

<math>d(h)^2 = {D^2}   \left({H-h \over H-h_b}\right)^{1.6} </math>

where:

<math>d(h)</math> = stem diameter at height h,

<math>D</math> = tree diameter at breast height,

<math>H</math> = tree total height,

<math>h</math> height of interest (h ≤ H), and

<math>h_b</math> = breast height.

Once developed, taper equations can be used to predict the diameter at a given height, or the height for a given diameter.

==See also==
* [Judson Freeman Clark#International 1/4-inch log rule](/source/Judson_Freeman_Clark)

== Footnotes ==
<references/>

{{Forestry}}

Category:Forest modelling

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