Soil Organic Carbon (SOC)

AUS-TMI-FOR-SOC General Moderate confidence

Benchmark Value

10.5 %
Direction: Higher is desirable ↑
Form: Point

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context. The scoring engine uses 6 benchmarks together — the OptimalRange form drives the primary score, while 5 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary MinimumOnly Guard Point Guard OptimalRange Guard MinimumOnly Guard Point Guard

Evidence & Context

The Zinn et al. study reports a mean Soil Organic Carbon content of 105 g kg⁻¹, which is equivalent to 10.5%, in the surface soil layer (0–5 cm) of the Araucaria angustifolia plantation.

Metric Definition:

Soil Organic Carbon content in the surface soil layer (0–5 cm)

Benchmark Definition:

This benchmark represents the Soil Organic Carbon content as a percentage of soil mass in the top 0–5 cm soil layer for production forestry in the Tropical & Subtropical Maritime Islands biome. It indicates a high ecological function state based on a proxy study from a similar climate and soil setting.

Justification:

Derived from a peer-reviewed study of a 30-year-old Araucaria plantation in a highly analogous climate and soil setting, selected as a proxy due to the systemic exclusion of Australian maritime islands from national soil monitoring programs.

Supporting Sources (6)

Additional references from the underlying research that informed this benchmark.

Preview of Categories - SOIL - CSIRO Data Access Portal, accessed July 25, 2025,
Categories - SOIL - CSIRO Data Access Portal, accessed July 25, 2025,
Contextual Support Government

CSIRO Data Access Portal

View Source
Preview of Change in Organic Carbon in Forest Plantation Soils in Eastern Australia - ResearchGate, accessed July 25, 2025,
Change in Organic Carbon in Forest Plantation Soils in Eastern Australia - ResearchGate, accessed July 25, 2025,
Contextual Support GreyLiterature

Temperate forests and soils [Chapter 6], accessed July 20, 2025,

View Source
Preview of LORD HOWE ISLAND A Summary of Current and Projected Scientific and Environmental Activities - Australian Museum, accessed July 30, 2025
LORD HOWE ISLAND A Summary of Current and Projected Scientific and Environmental Activities - Australian Museum, accessed July 30, 2025
Contextual Support Journal

Baseline high-resolution maps of organic carbon content in Australian soils - PMC

View Source
Preview of Norfolk Island Environmental Assessment Executive Summary
Norfolk Island Environmental Assessment Executive Summary
Contextual Support GreyLiterature

Norfolk Island Environmental Assessment Executive Summary

View Source
Preview of Soil Carbon Stock and Indices in Sandy Soil Affected by Eucalyptus Harvest Residue Management in the South of Brazil - MDPI
Soil Carbon Stock and Indices in Sandy Soil Affected by Eucalyptus Harvest Residue Management in the South of Brazil - MDPI
Contextual Support Journal

Soil Carbon Stock and Indices in Sandy Soil Affected by Eucalyptus Harvest Residue Management in the South of Brazil - MDPI

View Source
Preview of Soil organic carbon stocks under plantation forests in a humid, montane region of tropical Brazil
Soil organic carbon stocks under plantation forests in a humid, montane region of tropical Brazil
Direct Evidence

Soil organic carbon stocks under plantation forests in a humid, montane region of tropical Brazil

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Maritime Islands
  • Land Use Production Forestry
  • Assessment Not Stated
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 5 Jun 2026

Notes

Lower Critical Threshold: 2 %. No upper detrimental threshold — higher values are always better up to natural saturation. This value represents a state of high ecological function, as the plantation's SOC stock significantly exceeded that of the adjacent native forest, demonstrating that well-managed production forestry can be a net carbon sink. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.