G4M Interpret Yield Table #
G4M › Interpret Yield Table fits the G4M growth coefficients c0–c7 for each tree species from a yield table.
This tool needs the G4M back end. Contact the FLAM team if you are interested in this module.
Yield table format #
The yield table is an Excel workbook (.xlsx) with one sheet per species and these columns (the tool preselects them by name):
| Column | Content |
|---|---|
| Site Index | Site index of the yield class |
| Age | Stand age (years) |
| Num of tree | Trees per hectare |
| Volume | Stem volume (m³/ha) |
| Species Info / Info Value | Rows D (wood density), BEF (biomass expansion factor) and R (root-to-shoot ratio) with their values |
Use #
- Select the Yield Table, or click ¶ to load it from the configuration.
- Check the column mapping. Keep Estimate dead wood on to add the volume of trees lost through self-thinning.
- Click Optimize Parameters (C0~C7) and choose where to save the coefficient table (
.xlsx). - To check a fit, pick a Species and click Validate. In the validation window, you can edit initial values and bounds, then click Refresh to refit or Reset to restore the defaults. Test SI plots the curve for a chosen site index.
What is fitted #
Carbon = (volume + dead wood) · D · BEF · (1 + R) · 0.5
ShapeFactor = c0 + c1 · exp(c2 · SI^c3)
tMax = c4 + c5 / (1 + exp(c6 + c7 · SI))
The tool fits an age–carbon curve to each site index. c0–c7 then describe how the curve’s shape factor and its age of maximum growth (tMax) change with the G4M site index.