Microbial Biomass Carbon (MBC)

AUS-TMS-CON-SMB General Moderate confidence

Benchmark Value

425 mg/kg
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 9 benchmarks together — the OptimalRange form drives the primary score, while 8 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

The benchmark value of 425 mg/kg represents the best available condition for a healthy, fire-adapted tropical savanna conservation area.

Metric Definition:

Microbial Biomass Carbon (MBC) represents the total mass of living microorganisms within the soil, measured as carbon content of the microbial biomass.

Benchmark Definition:

A proxy-based benchmark for Microbial Biomass Carbon in tropical monsoonal savannas under conservation management.

Justification:

Derived using a proxy method applying a Microbial Quotient (MQ) of 2.5% to the mean Soil Organic Carbon (SOC) of 1.7% measured at the Ranger Conceptual Reference Ecosystem, representing best-practice conservation management.

Sources (1)

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, GreyLiterature

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

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Supporting Sources (4)

Additional references from the underlying research that informed this benchmark.

Preview of Altered soil microbial community at elevated CO2 leads to loss of soil carbon | PNAS, accessed August 5, 2025
Altered soil microbial community at elevated CO2 leads to loss of soil carbon | PNAS, accessed August 5, 2025
Contextual Support

Altered soil microbial community at elevated CO2 leads to loss of soil carbon | PNAS

View Source
Preview of functions-of-soil-organic-matter-and-the-effect-on-soil-properties.pdf.pdf, accessed July 19, 2025,
functions-of-soil-organic-matter-and-the-effect-on-soil-properties.pdf.pdf, accessed July 19, 2025,
Contextual Support Journal

The biodiversity cost of carbon sequestration in tropical savanna - PMC - PubMed Central

View Source
Preview of Microbial Biomass C, N and P in Disturbed Dry Tropical Forest Soils, India
Microbial Biomass C, N and P in Disturbed Dry Tropical Forest Soils, India
Contextual Support Journal

Microbial Biomass C, N and P in Disturbed Dry Tropical Forest Soils, India

View Source
Preview of Supervising Scientist Report 671: Woody biomass dynamics at Paradise Farm, a long-term fire experiment in the savannas of northern Australia
Supervising Scientist Report 671: Woody biomass dynamics at Paradise Farm, a long-term fire experiment in the savannas of northern Australia
Direct Evidence

Supervising Scientist Report 671: Woody biomass dynamics at Paradise Farm, a long-term fire experiment in the savannas of northern Australia

View Source

Context

  • Region Australia
  • Biome Tropical Monsoonal Savannas
  • Land Use Conservation / Protected Natural Areas
  • Assessment Pristine Reference
  • Season wet season
  • Evidence Type ReferenceCondition

Lifecycle

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

Notes

This benchmark represents the best available condition in a fire-adapted tropical savanna conservation area, derived from proxy calculations due to lack of direct MBC measurements.

Related Benchmarks

Other benchmarks in the AUS-TMS-CON-SMB family.

— mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference · wet season
OptimalRange Active v1