Calculation of growth

Introduction

Growth from one period to another period is done as follows (assuming 5-year periods)

Make a growth prognosis based on the residual state (state after treatment, if any) of the treatment unit
Calculate the state in the new period
Assign height and volume to trees in the new period (based on the state before treatment in the new period)
Make growth adjustments that are treatment related

Growth prognosis is done in the following steps, per prediction unit:

Update tree values
1. Determine Bal for each tree (basal area of all larger trees)
2. Determine if each tree is an overstorey tree or not
3. If any tree changed to/from overstorey, update aggregated values for the prediction unit (e.g. mean age, total volume, and mean diameter), since some of these values are per forest layer
Assign diameter growth and mortality to trees
Assign height growth and mortality to saplings
Prognos ingrowth (only if stand is established)
Adjust diameter growth due to stand growth model and thinning effect

Set the values for the new period:
1. Update diameter (for trees) or height (for saplings), and stems (for both trees and saplings)
If there are saplings but not waiting saplings, and mean height exceeds height limit for young stand, change saplings to trees:
1. Change tree type of saplings with diameter < 4 cm to removed
2. Change tree type of remaining saplings to trees
3. Update aggregated values for each prediction unit where there was saplings
If there are ingrown trees:
1. Assign age, height, and growth to each ingrown tree
2. Update aggregated values for each prediction unit where there was ingrown trees
If aggregated values for any prediction unit has been changed, update aggregated values for the treatment unit
Perform growth adjustment that is not treatment related