Kozak Taper Curve Calculator

Explicit Kozak 1969 squared relative diameter quadratic, not later variable-exponent Kozak editions or linear taper; independently calibrated coefficients/unit convention. Caller independently verifies units, applicability and matching conditions; no operational recipe, safety certification, causal efficacy or legal/resource classification is inferred.

Description

A Kozak 1969-style taper relation expresses squared relative diameter as a quadratic in relative height.

A Kozak 1969-style taper relation expresses squared relative diameter as a quadratic in relative height.^[1]

Coefficients belong to an independently calibrated population and do not transfer automatically across species or stand conditions. Use this tool to calculate kozak taper curve from the supplied measurements and assumptions.

When to use Kozak Taper Curve Calculator

Use this tool to calculate kozak taper curve from the supplied measurements and assumptions. Establish the species/site, survey protocol, units, sampled area or exposure, and the independently chosen reference or model.

How to use Kozak Taper Curve Calculator and understand its results

Establish the species/site, survey protocol, units, sampled area or exposure, and the independently chosen reference or model.
Enter callerDbhCm, callerKozak1969Coefficients, observedRelativeStemHeights, using the field meanings and rules below, then run the tool.
Read kozak1969DiameterCm. Interpret the fields using their units, signs and evidence conventions below.
If input validation fails, correct the reported field and run again. Before applying the result, check reference scope, model assumptions and any missing evidence or placeholder values.

Input field	Meaning	Value type	Requirement
callerDbhCm	Caller dbh cm	number	Required
callerKozak1969Coefficients	Caller kozak 1969 coefficients	list of number	Required
observedRelativeStemHeights	Observed relative stem heights	list of number	Required

Require positive DBH and exactly three finite caller coefficients, with relative heights in [0,1]. Evaluate a+bz+cz² at each submitted height and reject a negative value at any of those samples. Return DBH times its square root on the DBH length basis. Unsampled portions of the polynomial are not checked and no coefficient fitting is performed.

diameter(z)=DBH×√(a+bz+cz²)

Use the exact units, boundary rules, ordering and missing-evidence conventions above.

Output field	Meaning	Value type
kozak1969DiameterCm	Kozak1969 Diameter Cm; follow the units, sign, ordering and evidence convention stated above	list of number

json

{
  "input": {
    "callerDbhCm": 10,
    "callerKozak1969Coefficients": [
      1,
      -1,
      0
    ],
    "observedRelativeStemHeights": [
      0,
      0.5,
      1
    ]
  },
  "output": {
    "kozak1969DiameterCm": [
      10,
      7.0710678118654755,
      0
    ]
  }
}

Limitations and assumptions

Coefficients belong to an independently calibrated population and do not transfer automatically across species or stand conditions. Interpretation depends on the units, sampling scope and exact model described above.

All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse evidence arrays fail validation; the specific bounds and alignment requirements are stated above. Extremely large inputs or outputs can also be rejected. An input error is distinct from a successful result reporting false, no matches or missing evidence.

Alternative or Complementary methods

Use Diameter Height Allometry Calculator for this related task: A diameter–height relationship can be represented by a fitted power law over observed trees.

Use Site Index From Height Age Calculator when its separate inputs and assumptions fit the question: A Hossfeld-style height curve provides a chosen age–height relationship for a site-index comparison.

References

Kozak Taper Curve Calculator — tool.io

Similar or alternative tools

Diameter Height Allometry Calculator
A diameter–height relationship can be represented by a fitted power law over observed trees.
Site Index From Height Age Calculator
A Hossfeld-style height curve provides a chosen age–height relationship for a site-index comparison.