kozak.94_hi: Estimate the height at which a given diameter occurs in a...

In sergiocostafh/timbeR: Calculate Wood Volumes from Taper Functions

Estimate the height at which a given diameter occurs in a tree, based on a fitted Kozak (1994) taper equation.

Description

Estimates the height at which a given diameter occurs in a tree, from the diameter at breast height, total height and coefficients of the Kozak (1994) taper function.

Usage

kozak.94_hi(dbh, h, di, coef, p)

Arguments

dbh	tree diameter at breast height, in centimeters.
h	total tree height, in meters.
di	diameter whose height of occurrence will be estimated, in centimeters.
coef	numerical vector containing nine coefficients of the Kozak (1994) taper function.
p	numerical value representing the first inflection point calculated in the segmented model of Max and Burkhart (1976).

Details

the Kozak (1994) variable-form taper function is represented mathematically by the following expression

b0*(dbhb1)*(b2dbh)((1-(hi/h)^0.5)/(1-p^0.5))^(b3+b4(hi/h)^(1/4)+b5*((hi/h))^(1/3)+b6*((hi/h)^0.5)+b7asin(1-(hi/h)^0.5)+b8(1/((dbh/h)+1))+b9*h)

Value

a numeric value indicating the height at which the given diameter occurs.

Examples

library(dplyr)
library(minpack.lm)
library(timbeR)

tree_scaling <- tree_scaling %>%
mutate(did = di/dbh,
       hih = hi/h)

kozak.94 <-  nlsLM(di ~ taper_kozak.94(dbh, h, hih, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, p),
data=tree_scaling,
start=list(b0=1.5,b1=1.5,b2=1,b3=-10,b4=50,b5=-10,b6=34,b7=10,b8=-1,b9=-0.01, p = .1))

coef_kozak.94 <- coef(kozak.94)[-11]
p_kozak.94 <- coef(kozak.94)[11]

dbh <- 25
h <- 20
di <- 5

kozak.94_hi(dbh, h, di, coef_kozak.94, p_kozak.94)

sergiocostafh/timbeR documentation built on Feb. 13, 2025, 8:01 p.m.