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Estimate tree merchantable volume using Fortin et al. (2007) model (QC)

vol_fortin2007.Rd

Deterministic (fixed-effects only) implementation of the Fortin et al. general merchantable volume model developed for Québec forests.

Usage

vol_fortin2007(DBH, height, species)

Source

Fortin, M., DeBlois, J., Bédard, S., Meunier, S. (2007). Mise au point d’un tarif de cubage général pour les forêts québécoises : une approche pour mieux tenir compte des effets de la dimension des arbres. Gouvernement du Québec, Ministère des Ressources naturelles et de la Faune.

Full reference implementation: https://github.com/CWFC-CCFB/CFSForestTools

Arguments

DBH

Numeric vector of diameter at breast height (cm).

height

Numeric vector of total tree height (m).

species

Character vector of species codes (standardized with `standardize_species_code()`).

Value

A tibble with volumes (m^3):

vol_total

Numeric. Total volume (m\(^3\)). Currently returned as NA as a placeholder; total volume will be handled later via expansion factors.

vol_merchantable

Numeric. Merchantable stem volume (m\(^3\), under bark).

Details

This function returns merchantable stem volume (under bark) at the individual-tree level as a function of diameter at breast height (DBH) and total tree height. Only the fixed-effects (mean) component of the original mixed-effects formulation is implemented in CanadaForestAllometry; stochastic components (random effects and residual variance) are intentionally omitted.

Merchantable volume is defined according to Québec provincial inventory standards. Trees with DBH < 9.1 cm are considered non-merchantable and have merchantable volume equal to zero.

Users requiring the complete mixed-effects model formulation and full functionality (e.g., stochastic predictions and uncertainty propagation) are directed to the official Java implementation available in the CFSForestTools repository: https://github.com/CWFC-CCFB/CFSForestTools

Examples

# Single tree
vol_fortin2007(
  DBH = 20,
  height = 18,
  species = "PICE.MAR"
)
#> # A tibble: 1 × 2
#>   vol_total vol_merchantable
#>       <dbl>            <dbl>
#> 1        NA            0.235

# Multiple trees, vectorized
vol_fortin2007(
  DBH = c(18, 25, 32),
  height = c(15, 20, 24),
  species = c("ABIE.BAL", "PICE.GLA", "PINU.BAN")
)
#> # A tibble: 3 × 2
#>   vol_total vol_merchantable
#>       <dbl>            <dbl>
#> 1        NA            0.157
#> 2        NA            0.423
#> 3        NA            0.813