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Auger and Ward (2021) site index model for Quebec plantations

Source: R/si_augerward2021.R
si_augerward2021.Rd

Implementation of the dominant-height difference equations reported by Auger and Ward (2021) for jack pine plantations (PINU.BAN) and black spruce plantations (PICE.MAR) in Quebec.

Usage

si_augerward2021(age, height = NULL, si = NULL, species, base_age = 25)

Arguments

age

Numeric vector. Plantation age (years), with `age > 0`. A warning is emitted when `age > 100`, because that exceeds the recommended range in the source document.

height

Optional numeric vector. Dominant height (m). If provided, `si` is predicted.

si

Optional numeric vector. Site index (m) at `base_age` years. If provided, `height` is predicted.

species

Character vector of species codes (e.g., `"PINU.BAN"` or `"PICE.MAR"`).

base_age

Positive numeric scalar. Site-index base age (years since planting). Defaults to `25`.

Value

A tibble with columns:

height

Predicted dominant height (m), returned when input `si` is provided.

si

Predicted site index (m), returned when input `height` is provided.

Details

Species coverage: PINU.BAN, PICE.MAR.

Geographic use: Quebec plantations.

Age definition note: `age` is plantation age (years since planting), not breast-height age.

Height definition note: the model uses dominant height (m) based on the mean height of the 100 tallest planted trees per hectare.

Base-age note: the source document defines `IQS` at plantation age 25 years. The equations are written as difference equations, so other positive `base_age` values can also be used.

Domain note: the source recommends limiting use to plantation ages up to 100 years. This implementation warns when `age > 100` and returns extrapolated values.

Provide exactly one of `height` or `si`:

  • If `height` is provided, the function predicts `si`.

  • If `si` is provided, the function predicts `height`.

Inputs and outputs are metric and follow the source model scale directly.

References

Auger, I., & Ward, C. (2021). Tables de rendement pour les plantations d'epinette noire et les plantations de pin gris au Quebec. Avis technique SSS-06. Gouvernement du Quebec. Version corrigee diffusee en 2024.

Examples

si_augerward2021(
  age = c(20, 30),
  si = c(9, 12),
  species = c("PICE.MAR", "PINU.BAN")
)
#> # A tibble: 2 × 1
#>   height
#>    <dbl>
#> 1   7.13
#> 2  14.0 

si_augerward2021(
  age = c(20, 30),
  height = c(7, 10),
  species = c("PICE.MAR", "PINU.BAN")
)
#> # A tibble: 2 × 1
#>      si
#>   <dbl>
#> 1  8.85
#> 2  8.37