silv_basal_area: Calculates Basal Area

In silviculture: Utility Functions for Forest Inventory and Silviculture

Calculates Basal Area

Description

Calculates Basal Area in square meters.

Usage

silv_basal_area(diameter, ntrees = NULL, units = "cm")

Arguments

diameter	Numeric vector of diameters or diameter classes
ntrees	Numeric vector with number of trees of the diameter class per hectare. If ntrees = NULL, the function will assume that each diameter corresponds to only one tree. Therefore, basal area will be calculated for each individual tree
units	The units of the diameter (one of cm, mm, or m)

Details

The function uses the next formula:

G = \frac{\pi}{40000} \cdot D^2

where G is the basal area in m^2, and D is the diameter in the units specified in the function. It is recommended to use the squared mean diameter calculated with silv_sqrmean_diameter

Value

A numeric vector

Examples

## calculate G for inventory data grouped by plot_id and species
library(dplyr)
inventory_samples |>
mutate(dclass = silv_diametric_class(diameter)) |>
  summarise(
    height = mean(height, na.rm = TRUE),
    ntrees = n(),
    .by    = c(plot_id, species, dclass)
  ) |>
  mutate(
    ntrees_ha = silv_ntrees_ha(ntrees, plot_size = 10),
    dg        = silv_sqrmean_diameter(dclass, ntrees_ha),
    g         = silv_basal_area(dclass, ntrees_ha),
    .by       = c(plot_id, species)
  )

## calculate individual basal area
silv_basal_area(c(23, 11, 43.5, 94))

silviculture documentation built on Nov. 5, 2025, 7:13 p.m.