GCubeR (version 0.1.3)

algan_vta_vc22: Volume Estimation Using the Algan Method

Description

Computes aerial total volume (algan_vta) and merchantable volume (algan_vc22) according to the Algan method. The function validates input data, ensures required columns are present and applies formulas only to compatible species.

Usage

algan_vta_vc22(data, output = NULL)

Value

A data frame with the original input columns plus two new outputs:

• algan_vta: aerial total volume (m3). Computed only for "ABIES_ALBA", NA otherwise.

• algan_vc22: merchantable volume (m3). Computed only for compatible species (ABIES_ALBA, PICEA_ABIES, ALNUS_GLUTINOSA, PRUNUS_AVIUM, BETULA_SP), NA otherwise.

Arguments

data

A data frame containing tree measurements. Must include:

• species_code: species name in uppercase Latin format (e.g. "ABIES_ALBA").

• dbh: diameter at breast height (cm).

• htot: total tree height (m).

output

Optional file path where the resulting data frame should be exported as a CSV. If NULL (default), no file is written. Export is handled by the utility function export_output() and failures trigger warnings without interrupting execution.

Details

• Input dbh must be in centimeters (cm). The function converts it internally to meters.

• Input htot must be in meters (m).

• Formula for aerial total volume (only "ABIES_ALBA"): $$algan_vta = 0.4 * (dbh/100)^2 * htot$$

• Formula for merchantable volume (compatible species): $$algan_vc22 = 0.33 * (dbh/100)^2 * htot$$

  • Domain of application:

  • For "ABIES_ALBA" and "PICEA_ABIES", the Algan method is valid only if dbh > 15 cm.

  • For other compatible species (ALNUS_GLUTINOSA, PRUNUS_AVIUM, BETULA_SP), no minimum dbh threshold is applied.

• Resulting volumes are expressed in cubic meters (m3).

• If required columns are missing or non-numeric, the function stops with an error.

• Both output columns are always created to ensure consistency for downstream functions.

Examples

df <- data.frame(
  species_code = c("ABIES_ALBA", "PICEA_ABIES", "BETULA_SP", "QUERCUS_ROBUR"),
  dbh = c(30, 25, 20, 40), 
  htot = c(20, 18, 15, 22)   
)
algan_vta_vc22(df)