Thinning Q-Factor Diameter Step
Normalize caller descending geometric q targets over equally spaced diameter classes, conserving supplied total density; these are continuous planning targets, not actual integer trees or an ecological prescription.
Description
A q-factor stand target imposes a geometric ratio between neighboring diameter classes.
A q-factor stand target imposes a geometric ratio between neighboring diameter classes. Normalizing class weights preserves the caller's total target stem density.1
Normalize caller descending geometric q targets over equally spaced diameter classes, conserving supplied total density; these are continuous planning targets, not actual integer trees or an ecological prescription.
When to use Thinning Q-Factor Diameter Step
Use this tool to normalize caller descending geometric q targets over equally spaced diameter classes, conserving supplied total density; these are continuous planning targets, not actual integer trees or an ecological prescription.
Gather the tree inventory, plot measurements or model parameters. Check diameter, area, time and moisture conventions; keep paired observations aligned.
How to use Thinning Q-Factor Diameter Step and understand its results
- Gather the tree inventory, plot measurements or model parameters. Check diameter, area, time and moisture conventions; keep paired observations aligned.
- Enter diameterClassMidpointsCm, qSmallToNextLargeClass, targetTotalStemsPerHa using the field table and calculation rules, then run the tool.
- Read targetClassStemsPerHa. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| diameterClassMidpointsCm | Diameter class midpoints cm | list of number | Required |
| qSmallToNextLargeClass | Q small to next large class | number | Required |
| targetTotalStemsPerHa | Target total stems per ha | number | Required |
Use at least two increasing positive class midpoints, equally spaced within relative 10⁻⁹ step tolerance, q≥1 and nonnegative total stems/ha. Return continuous class targets in midpoint order; q=1 gives equal targets.
Each sequence checked for increasing order must contain at least two strictly increasing values.
class target=total target × q^(−index)/Σq^(−index) Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| targetClassStemsPerHa | Target class stems per ha | list of number |
{
"input": {
"diameterClassMidpointsCm": [
10,
20,
30
],
"qSmallToNextLargeClass": 2,
"targetTotalStemsPerHa": 70
},
"output": {
"targetClassStemsPerHa": [
40,
20,
10
]
}
}Limitations and assumptions
Targets are not integer trees or an ecological thinning prescription. Class spacing and total density are caller choices.
Numeric inputs and returned numeric values must be finite; an unrepresentable returned value produces an error. Numeric lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Weibull Diameter Distribution: Predict Weibull diameter-class count inventory under supplied shape/scale, retaining below/above surveyed class tails; not random sampling or inferred stand-table coefficients. For a complementary task, use Self Thinning Slope: Fit log mean-stem dry mass versus log stem density to observed self-thinning samples; unlike Reineke DBH stand density, no fixed -3/2 slope or maximum-density relationship is imposed.
References
-
Thinning Q-Factor Diameter Step — tool.io
Similar or alternative tools
- Weibull Diameter Distribution
Predict Weibull diameter-class count inventory under supplied shape/scale, retaining below/above surveyed class tails; not random sampling or inferred stand-table coefficients.
- Self Thinning Slope
Fit log mean-stem dry mass versus log stem density to observed self-thinning samples; unlike Reineke DBH stand density, no fixed -3/2 slope or maximum-density relationship is imposed.