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
Make growth prognosis
Growth prognosis is done in the following steps, per prediction unit:
- Update tree values
- Determine Bal for each tree (basal area of all larger trees)
- Determine if each tree is an overstorey tree or not
- 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
Calculate state in a new period
- Set the values for the new period:
- 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:
- Change tree type of saplings with diameter < 4 cm to removed
- Change tree type of remaining saplings to trees
- Update aggregated values for each prediction unit where there was saplings
- If there are ingrown trees:
- Assign age, height, and growth to each ingrown tree
- 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
Assigning height and volume
For each prediction unit:
- Height and volume is assigned to trees
- Volume is assigned to saplings
- If first period, dead trees is estimated
- Aggregated volume is updated