Defining Growth Curves

This guide shows how to define custom growth curves for forest development types.

Prerequisites

• A loaded ForestModel

• Age-volume data as pairs (age, volume)

Procedure

1. Prepare age-volume data

points = [
    (10, 15.2), (20, 45.8), (30, 95.3), (40, 165.7),
    (50, 258.4), (60, 368.2), (70, 485.9), (80, 602.1),
    (90, 715.3), (100, 820.5)
]

2. Create a Curve object

from ws3.core import Curve

curve = Curve(
    label="SP_SI50_Volume",
    is_volume=True,
    points=points,
    period_length=10
)

3. Register with the model

fm.register_curve(curve)

4. Query the curve

vol_45 = curve.lookup(45)
print(f"Volume at age 45: {vol_45:.1f} m3/ha")

Notes

• Ages must be in ascending order.

• Curve.lookup() performs linear interpolation between data points.