# Method

How each equation gets in, how it is checked, and how it stays current.

## What gets in

- Tree-level equations for biomass (above and below ground, and by component), stem volume, height and root:shoot ratios.
- Taken from the paper that published them. Compilations such as GlobAllomeTree only tell us where to look. When we could only read a compilation, the equation is marked from a compilation.
- Stand-level (per hectare) models are left out.

## How an equation is recorded

- The equation exactly as printed, with where it appears (table, equation number, page).
- Short quotes for every fact we state: number of trees, fitted ranges, R², correction factors. If the paper doesn't say, we leave it blank. We never infer a number.
- Two versions of the formula: the paper's own, in its units, and the library's, in common units (DBH in cm, height in m, wood density in g/cm³, biomass in kg dry mass, volume in m³), with any back-transformation correction factor applied.

## How it is checked

- Each equation carries at least one worked example. Where the paper prints a predicted value, we use it.
- On every build, the library's formula and the paper's formula (after unit conversion) must both reproduce that example within 1%. This catches the most common errors: log base, units, and forgotten correction factors.
- Formulas are parsed by a small evaluator that only knows arithmetic and `ln`, `log10`, `exp` and `sqrt`. Nothing in the data can run code.

## How it stays current

- Every week a job looks each source's DOI up on Crossref and asks whether the publisher has posted a retraction or correction; a source without a DOI has its link checked instead. Unchanged sources get a new checked date; anything else opens a pull request for review.
- The same job searches OpenAlex for newly published allometry papers and lists them as candidates in the repository, so new equations are added from the papers themselves.
- Each equation and source shows the date it was last checked.

## Using the numbers

- Prefer an equation fitted on your species and region, inside its fitted DBH range. The calculator warns when you go outside it.
- Carbon is shown as biomass × 0.47 (IPCC 2006 Guidelines, Vol. 4, Ch. 4, Table 4.3); CO₂e as carbon × 44/12. Use your standard's own fraction where it differs.
- Wood density values: the [Global Wood Density Database](https://doi.org/10.5061/dryad.234) (Zanne et al. 2009) is the usual source.

## Licence and corrections

The data is © 2026 Restoration Scope and licensed [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). Quotes from papers stay their authors' work; they are kept short and link to the source. Code is MIT. Download everything as [JSON](https://treeallometry.org/data/equations.json) or [CSV](https://treeallometry.org/data/equations.csv).

Found a wrong number? [Email us](mailto:info@restorationscope.com) at info@restorationscope.com. A paper we should add? [Send it to us](https://treeallometry.org/contribute/): we do the data entry.

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