taperNOR: Taper model for spruce, pine, and birch in Norway

In JohannesRahlf/taperNO:

Taper model for spruce, pine, and birch in Norway

Description

Computes stem diameters (taper) along the bole of spruce, pine, and birch in Norway. The function implements the taper equations described in Hansen et al. (2023), based on Kozak’s (1988) variable-exponent taper equation. The original article by Hansen et al. (2023) contains minor errata (e.g., missing brackets, the use of 'Log' instead of 'ln', and a sign error at 'b7' in the pine taper model), but these do not affect the present implementation.

Usage

taperNOR(h, dbh, h_top, sp = "spruce", with_bark = TRUE)

Arguments

h	A numeric vector of heights above ground (in meters) at which to return diameters.
dbh	Diameter at breast height (1.3 m above ground), over bark (in centimeters).
h_top	Total tree height (in meters).
sp	Character or numeric value indicating the species; recognized inputs include: spruce: "spruce", "s", "gran", "g", "1" pine: "pine", "p", "furu", "f", "2" birch: "birch", "b", "bjørk", "bjork", "bj", "lauv", "l", "3" Defaults to "spruce".
with_bark	Logical. If TRUE (the default), returns diameter over bark. If FALSE, diameter under bark is computed by subtracting bark thickness via barkNOR.

Value

A numeric vector of diameters (in centimeters) at each height in h.

References

Hansen, E., Rahlf, J., Astrup, R., & Gobakken, T. (2023). Taper, volume, and bark thickness models for spruce, pine, and birch in Norway. Scandinavian Journal of Forest Research, \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1080/02827581.2023.2243821")}.

Kozak, A. (1988). A variable-exponent taper equation. Canadian Journal of Forest Research, 18(11), 1363–1368.

See Also

barkNOR for details on bark thickness subtraction.

Examples

# Example usage:
# Calculate taper for pine, at heights 1:30 m, dbh = 20 cm, total height = 30 m:
taperNOR(h = 1:30, dbh = 20, h_top = 30, sp = "pine", with_bark = TRUE)

# To get diameters under bark:
taperNOR(h = 1:30, dbh = 20, h_top = 30, sp = "pine", with_bark = FALSE)

JohannesRahlf/taperNO documentation built on Feb. 17, 2025, 8:02 p.m.