A managed timber stand follows a site-index yield curve: volume climbs slowly at first, accelerates through the pole stage, then levels off as the canopy closes and competition limits growth. Foresters clear-cut at the rotation age that maximizes the mean annual increment (MAI) — the long-run average timber yield per hectare per year.
V(t) = K / (1 + e^(−b(t − t0))) (logistic site-index yield curve)
MAI(t) = V(t) / t → maximized where MAI = current annual increment
thinning removes a fraction of stems, boosting per-tree growth of survivors
- Rotation length — years between clear-cuts; too short wastes growth potential, too long lets MAI decline.
- Planting density — stems per hectare after each clear-cut; denser stands compete harder per tree.
- Thinning intensity — mid-rotation removal that concentrates growth on remaining trees.
- Time speed — fast-forwards simulated years so multiple rotations can be observed.
Commercial forestry (e.g. Nordic and Pacific-Northwest plantations) sets rotation ages around the MAI-maximizing point to balance timber revenue against land-use opportunity cost.