# GCubeR – Implementation

Function | Method | Outputs | Inputs | Main formula (generic form) | Notes / Context
--- | --- | --- | --- | --- | ---
Converting module
`c150_c130()` | Convert `c150` to `c130` or Convert `c130` to `c150` | `c150` `c130` | `c130` `c150` | `c130=a⋅c150+b` `c150=(c130-b)/a` | The function computes `c150` or `c130` depending on data availabity
`add_c130_dbh()` | Add or compute `c130` and `dbh` | `c130` `dbh` | `dbh` `c130` | `dbh = c130 / π` `c130 = dbh · π` | Auto-fills missing `c130` or `dbh`.
General & widely applicable volume models
`dagnelie_vc22_1()` | Dagnelie single entry | `vc22` | `c130` | `vc22 = a + b·c130 + c·c130² + d·c130³` | Simplest Dagnelie taper model, relies only on circumference.
`dagnelie_vc22_1g()` | Dagnelie graduaded | `vc22` | `c130` `hdom` | `vc22 = a + b·c130 + c·c130² + d·c130³ + e·hdom + f·c130²·hdom` | Improves accuracy in pure, even-aged stands by adding dominant height.
`dagnelie_vc22_2()` | Dagnelie 2 entry | `vc22` | `c130` `htot` | `vc22 = a + b·c130 + c·c130² + d·c130³ + e·htot + f·c130²·htot` | Most precise Dagnelie model; recommended mainly for high-value trees due to height measurement cost.
`dagnelie_br()` | Dagnelie – Branch volume | `vbr` | `c130` | `vbr = a + b·c130 + c·c130² + d·c130³` | Estimates branch volume from circumference only.
`vallet_vta()` | Vallet - Volume above ground | `vta` | `c130` `htot` | `form = (a + b·c130 + c·c130/htot)·(1 + d·c130²)` `vta = form · (π / 40000) · c130² · htot` | Explicitly models stem form factor; primarily for French species.
`vallet_vc22()` | Vallet merchantising volume | `vc22` | `dbh` `htot` | `vc22 = a·htot/dbh + (b + c·dbh)·π·dbh²·htot / 40000` | Geometrically adjusted; species-specific coefficients reflecting stem structure.
Context-specific methods
`algan_vta_vc22()` | Algan - volume computer(2006) | `vta` `vc22` | `dbh` `htot` | `vta = 0.40 · (dbh/100)² · htot` `vc22 = 0.33 · (dbh/100)² · htot` | Simplified geometric estimator; mainly used in France for Abies alba.
`bouvard_vta()` | Bouvard - Volume above ground | `vta` | `dbh` `htot` | `vta = 0.50 · (dbh/100)² · htot` | Specific to oaks (Quercus sp.), especially in coppice-with-standards regimes.
`rondeux_vc22_vtot()` | Rondeux / Pauwels et al. (2022) | `vtot` `vc22` | `c130` `htot` | `vtot = a · c130² · htot` `vc22 = a + b · c130² · htot` | Wallonia-specific; calibrated for larch (Larix sp.) in small-circumference trees (first thinnings).
Biomass / carbon computer
`biomass_calc()` – CNPF pathway | CNPF / France Valley | `bag` `bbg` `btot` `carbon` `CO₂` | `vc22` | `bag = vc22 · feb · density` `bbg = exp(−a + b·ln(bag) + c)` `btot = bag + bbg` `C = 0.475 · btot` | `feb = 1.30` (conifers) `feb = 1.56` (broadleaves) carbon and CO₂ derived from total biomass.
`biomass_calc()` – Vallet pathway | Follow Vallet et al. (2006) | `bag` `bbg` `btot` `carbon` `CO₂` | `vallet_vta` | `bag = vta · density` `bbg = exp(−a + b·ln(bag) + c)` `btot = bag + bbg` | Used when `vallet_vta` is available root biomass is implicitly included.
Plot module
`plot_by_class()` | Plot histogram by class of `c130` | `vc22` `vta` `btot` |  |  | Class width can be adjusted by the breaks input in the function