Dendro Ring Count Tool

Count measured dendro rings with explicit inferred missing-ring and outer-loss assumptions; calendar anchors are supplied, not independently dated by counting.

Description

Observed tree-ring counts can be supplemented with explicitly inferred missing and outer rings.

Observed tree-ring counts can be supplemented with explicitly inferred missing and outer rings. Calendar dates require an independently supplied anchor rather than being established by counting alone.^[1]

Count measured dendro rings with explicit inferred missing-ring and outer-loss assumptions; calendar anchors are supplied, not independently dated by counting.

When to use Dendro Ring Count Tool

Use this tool to count measured dendro rings with explicit inferred missing-ring and outer-loss assumptions; calendar anchors are supplied, not independently dated by counting.

Prepare the artifact, site or survey measurements and any independently established calibration or model choices. Keep paired observations aligned and confirm units and coordinate conventions.

How to use Dendro Ring Count Tool and understand its results

Prepare the artifact, site or survey measurements and any independently established calibration or model choices. Keep paired observations aligned and confirm units and coordinate conventions.
Enter observedRingWidthsMm, missingRingCountsBeforeEach, estimatedMissingOuterRings, lastObservedRingCalendarYear using the field table and calculation rules, then run the tool.
Read observedRingCount, inferredRepresentedYears, firstRepresentedCalendarYear, outermostYearScenario. 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
observedRingWidthsMm	Observed ring widths mm	list of number	Required
missingRingCountsBeforeEach	Missing ring counts before each	list of number	Required
estimatedMissingOuterRings	Estimated missing outer rings	integer	Required
lastObservedRingCalendarYear	Last observed ring calendar year	number	Required

Pair positive observed widths in mm with nonnegative integer missing-ring counts before each observation. Supply a finite last-observed calendar year and nonnegative integer missing outer rings. Return observed count, inferred represented years, first represented year as anchor−span+1 and outermost-year scenario as anchor+missingOuter.

Paired lists must be nonempty and have equal lengths.

representedObservedSpan = observedCount + missingBefore; totalYears = span + missingOuter

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
observedRingCount	Observed ring count	number
inferredRepresentedYears	Inferred represented years	number
firstRepresentedCalendarYear	First represented calendar year	number
outermostYearScenario	Outermost year scenario	number

json

{
  "input": {
    "observedRingWidthsMm": [
      1,
      2,
      1
    ],
    "missingRingCountsBeforeEach": [
      0,
      1,
      0
    ],
    "estimatedMissingOuterRings": 2,
    "lastObservedRingCalendarYear": 2000
  },
  "output": {
    "observedRingCount": 3,
    "inferredRepresentedYears": 6,
    "firstRepresentedCalendarYear": 1997,
    "outermostYearScenario": 2002
  }
}

Limitations and assumptions

Missing-ring assumptions and calendar anchor are caller inputs. The tool does not cross-date, diagnose false rings or establish the original felling date.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. 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 Average Tree Ring Width: Calculate mean measured radial growth per represented year including multi-year measurements; not an unweighted width mean when measurements cover unequal time. For a complementary task, use Dendro Master Curve Match Checker: Scan all whole-ring offsets using signed Pearson correlation on supplied sequences, first offset breaking ties; candidate correlations and a caller cutoff are not a statistically validated dendro date.

References

Dendro Ring Count Tool — tool.io

Similar or alternative tools

Average Tree Ring Width
Calculate mean measured radial growth per represented year including multi-year measurements; not an unweighted width mean when measurements cover unequal time.
Dendro Master Curve Match Checker
Scan all whole-ring offsets using signed Pearson correlation on supplied sequences, first offset breaking ties; candidate correlations and a caller cutoff are not a statistically validated dendro date.