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Lafleche et al. (2013) ecological-site IQS curves for southern Quebec

Source: R/si_lafleche2013.R
si_lafleche2013.Rd

Implementation of the fixed ecological-site height curves published by Lafleche et al. (2013) for major commercial tree species in southern Quebec. Unlike the polymorphic `si_*` models in this package, these curves are selected by ecological key and use fixed coefficients for each species-region-(subregion)-type combination.

Usage

si_lafleche2013(
  age,
  species,
  ecological_region,
  ecological_type,
  ecological_subregion = NULL,
  curve_set = "potential",
  base_age = 50,
  include_metadata = FALSE
)

Arguments

age

Numeric vector. Corrected age above 1 m (years), with `age > 0`.

species

Character vector of NFI species codes (for example `"PICE.GLA"`).

ecological_region

Character vector of Quebec ecological-region codes (French source term: `region_ecologique`; for example `"4f"`).

ecological_type

Character vector of ecological-type codes (French source term: `type_ecologique`; for example `"MS22"`).

ecological_subregion

Optional character vector of ecological-subregion codes (French source term: `subregion_ecologique`) when needed, for example `"5eS"`. Defaults to `NULL`, which is treated as missing.

curve_set

Character scalar. One of `"potential"` or `"observed"`. Defaults to `"potential"`. These map internally to the source-table curve sets `IQSstation` and `IQSobserved`, respectively.

base_age

Positive numeric scalar. IQS reference age (years above 1 m). Defaults to `50`.

include_metadata

Logical scalar. If `TRUE`, append lookup metadata and fitted-curve metadata to the returned tibble.

Value

A tibble with columns:

height

Predicted height (m) at `age`.

si

Fixed-curve IQS value (m) at `base_age`.

When `include_metadata = TRUE`, additional columns describing the matched ecological key and parameter row are included.

Details

Species coverage: `ABIE.BAL`, `BETU.PAP`, `PICE.GLA`, `PICE.MAR`, `PICE.RUB`, `PINU.BAN`, `PINU.STR`, `POPU.GRA`, `POPU.TRE`, `THUJ.OCC`.

Geographic use: ecological types in southern Quebec.

Age definition note: `age` is corrected age above 1 m height (years).

Height definition note: the source curves predict stand height in metres, constrained to pass through `(age = 0, height = 1)`.

Base-age note: IQS is defined as predicted height at 50 years above 1 m. `base_age` defaults to `50`, but any positive scalar can be supplied.

This function always predicts height from `age`; it also returns the corresponding fixed-curve IQS value evaluated at `base_age`.

`curve_set` chooses between the two curve families reported in the source: `"potential"` corresponds to the fitted potential-height curves used to derive `IQSstation` in the report, whereas `"observed"` corresponds to the separate curves fitted to observed height growth (`IQSobserved`). In the source tables these appear as `IQSstation` and `IQSobserved`, respectively.

At present, `CR`, `WE`, and `LIN` equation forms are implemented directly from the publication and validated against the published `IQSstation` summaries. The single `LOGIST3` row is kept in the parameter data but raises an error here because its printed equation/coefficients have not yet been reconciled with the published table values.

References

Lafleche, V., S. Bernier, J.-P. Saucier, and C. Gagne. 2013. Indices de qualite de station des principales essences commerciales en fonction des types ecologiques du Quebec meridional. Quebec, ministere des Ressources naturelles, Direction des inventaires forestiers, 115 p.

Examples

si_lafleche2013(
  age = 50,
  species = "PICE.GLA",
  ecological_region = "2a",
  ecological_type = "MJ11"
)
#> # A tibble: 1 × 2
#>   height    si
#>    <dbl> <dbl>
#> 1   19.6  19.6

si_lafleche2013(
  age = c(25, 50),
  species = "ABIE.BAL",
  ecological_region = "3c",
  ecological_type = "MJ12",
  curve_set = "potential",
  include_metadata = TRUE
)
#> # A tibble: 2 × 15
#>   height    si curve_set  species_qc Species  ecological_region
#>    <dbl> <dbl> <chr>      <chr>      <chr>    <chr>            
#> 1   9.32  17.5 IQSstation SAB        ABIE.BAL 3c               
#> 2  17.5   17.5 IQSstation SAB        ABIE.BAL 3c               
#> # ℹ 9 more variables: ecological_region_description <chr>,
#> #   ecological_subregion <chr>, ecological_type <chr>,
#> #   ecological_type_description_fr <chr>, ecological_type_description_en <chr>,
#> #   equation_used <chr>, n_trees <int>, n_observations <int>, pseudo_r2 <dbl>

# Vectorized use with the pipe operator
trees_h <- tibble::tibble(
  species = c("ABIE.BAL", "PICE.GLA"),
  age = c(25, 50),
  ecological_region = c("3c", "2a"),
  ecological_type = c("MJ12", "MJ11")
)

trees_h |>
  dplyr::mutate(
    iqs_pred = si_lafleche2013(
      age = age,
      species = species,
      ecological_region = ecological_region,
      ecological_type = ecological_type
    )
  ) |>
  tidyr::unnest(iqs_pred)
#> # A tibble: 2 × 6
#>   species    age ecological_region ecological_type height    si
#>   <chr>    <dbl> <chr>             <chr>            <dbl> <dbl>
#> 1 ABIE.BAL    25 3c                MJ12              9.32  17.5
#> 2 PICE.GLA    50 2a                MJ11             19.6   19.6