Microbial Biomass Carbon (MBC)

AUS-TSW-FOR-SMB General Moderate confidence

Benchmark Value

200 mg/kg
Direction: Higher is desirable ↑
Form: MinimumOnly

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 3 benchmarks together — the OptimalRange form drives the primary score, while 2 guard(s) constrain the result.

Evidence & Context

Lower Critical Threshold: An MBC level below 200 mg/kg is considered critically low, representing a >50% loss from the reference state and analogous to severe degradation from land clearing.

Metric Definition:

Lower critical threshold for Microbial Biomass Carbon (MBC) indicating significant ecosystem degradation.

Benchmark Definition:

This benchmark defines a critical minimum level of Microbial Biomass Carbon below which soil biological function is severely impaired, indicating significant ecosystem degradation in temperate semi-arid woodlands under production forestry.

Justification:

Represents a >50% loss of MBC from the reference state, analogous to severe degradation observed when native ecosystems are converted to agriculture.

Sources (1)

Preview of Green Carbon in the Great Western Woodlands: A global opportunity for conservation, climate change and sustainable futures
Green Carbon in the Great Western Woodlands: A global opportunity for conservation, climate change and sustainable futures Journal

Green Carbon in the Great Western Woodlands: A global opportunity for conservation, climate change and sustainable futures

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Preview of Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org.au, accessed August 28, 2025,
Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org.au, accessed August 28, 2025,
Contextual Support GreyLiterature

Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org.au

View Source
Preview of The Effect of Harvest on Forest Soil Carbon: A Meta-Analysis - MDPI, accessed August 5, 2025
The Effect of Harvest on Forest Soil Carbon: A Meta-Analysis - MDPI, accessed August 5, 2025
Contextual Support Journal

Refining benchmarks for soil organic carbon in Australia's temperate ...

View Source

Context

  • Region Australia
  • Biome Temperate Semi-Arid Shrublands & Open Woodlands
  • Land Use Production Forestry
  • Assessment Conservation Target
  • Vegetation Woodland
  • Evidence Type DegradationThreshold

Lifecycle

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

Notes

Soils with MBC below this threshold are considered functionally impaired and do not meet minimum standards for a healthy, resilient woodland ecosystem.

Related Benchmarks

Other benchmarks in the AUS-TSW-FOR-SMB family.