silv_stand_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_stand_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
units	The units of the diameter (one of mm, cm, dm, or m)

Details

The function uses the next formula:

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

where G is the basal area in m^2, and D is the diameter in cm. If ntrees in the number of trees per hectare, then the result will be m^2/ha. It is recommended to use the squared mean diameter calculated with silv_stand_qmean_diameter().

Note that if ntrees = NULL, the output of the function will be exactly the same as in silv_tree_basal_area().

Value

A numeric vector

Examples

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

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