A Sunny Crown Profile Equation for Hinoki Cypress based on the Height Increment

概要

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The power equation r=az^b is often used to represent the sunny crown profile of conifers, where r is the crown radius (m) at distance z (m) from the tree apex, and a and b are parameters. When parameter b is invariant between trees, parameter a is the only independent variable that determines the sunny crown profile. Assuming that parameter b is invariant between trees, this study derived a sunny crown profile equation for Hinoki cypress (Chamaecyparis obtusa ENDL.) based on the power equation from the relationship between parameter a and the annual height increment HI (m/year):a=cHI^d where c and d are parameters. First, we derived the relationship a=cHI^d. Next, we evaluated the efficacy of the equation r=cHI^dz^b at representing the sunny crown profile of Hinoki cypress. Data were obtained from 112 trees in six pure stands of even-aged Hinoki cypress. The fit of the equation a=cHI^d to the data was good. The equation r=cHI^dz^b made more precise predictions than the equation r=az^b assumed that each of parameters a and b is common to all trees. The values of parameters b, c, and d estimated from the sample trees were 0.686, 0.401, and -0.299, respectively. The integration of the sunny crown profile equation r=cHI^dz^b with a tree growth model, including the total height growth and the sunny crown length estimations, enables prediction of the sunny crown profile and its change with growth for Hinoki cypress.
森林計画学会の論文
2005-04-00