h_dom_weise: Weise's Dominant Height

In ForestElementsR: Data Structures and Functions for Working with Forest Data

Weise's Dominant Height

Description

The dominant height after Weise is the quadratic mean height of the 20% biggest trees in a stand. In contrast to the dominant height h_100 it is well defined not only in monospecific stands, but also in mixed stands.

Usage

h_dom_weise(h, d, n_rep = 1)

Arguments

h	vector of tree height values to calculate Weise's dominant height from
d	vector of stem diameters at breast height corresponding to h, must therefore have the same length as h
n_rep	vector of representation numbers (typically the number of trees per ha corresponding to the diameter at the same position), will be used as individual weights for each height, together with the squared diameters d. If n_rep has length 1, it will be recycled to the length of d. Otherwise, if the length of n_rep does not correspond to the length of d, the function will terminate with an error.

Value

The value of Weise's dominant diameter resulting from the input data

See Also

Other stand heights: h_100(), h_q(), h_q_from_d_q()

Examples

# A sample of trees from an angle count sample , where each
# tree represents a basal area of 4 m²/ha
d_cm <- c(12, 13, 25, 27, 28, 26, 26.1, 32, 35, 31, 42)
n_rep_ha <- 4 / ((d_cm / 100)^2 * pi / 4) # representation number of each tree
dq_cm <- d_q(d_cm, n_rep_ha)
h_m <- 0.9 * dq_cm * (d_cm / dq_cm)^0.8 # quick plausible height estim.
h_dom_weise(h_m, d_cm, n_rep_ha)
h_100(h_m, d_cm, n_rep_ha) # dominant height h100 for comparison
h_q(h_m, d_cm) # quadratic mean height for comparison

# if 20% of the trees are 100 stems/ha, Weise's dominant diameter and
# d100 are equal
d_cm <- rnorm(n = 500, mean = 35, sd = 7)
dq_cm <- d_q(d_cm)
h_m <- 0.8 * dq_cm * (d_cm / dq_cm)^0.8 # quick plausible height estim.
h_dom_weise(h_m, d_cm, 1)
h_100(h_m, d_cm, 1)

# Weise's dominant diameter is greater than d100, if 20% of the trees
# represent less than 100 trees/ha
d_cm <- rnorm(n = 200, mean = 35, sd = 7)
dq_cm <- d_q(d_cm)
h_m <- 0.8 * dq_cm * (d_cm / dq_cm)^0.8 # quick plausible height estim.
h_dom_weise(h_m, d_cm, 1)
h_100(h_m, d_cm, 1)

# Weise's dominant diameter is smaller than d100, if 20% of the trees
# represent more than 100 trees/ha
d_cm <- rnorm(n = 800, mean = 35, sd = 7)
dq_cm <- d_q(d_cm)
h_m <- 0.8 * dq_cm * (d_cm / dq_cm)^0.8 # quick plausible height estim.
h_dom_weise(h_m, d_cm, 1)
h_100(h_m, d_cm, 1)

ForestElementsR documentation built on April 3, 2025, 7:47 p.m.