Microbial Biomass Carbon (MBC)

AUS-TGP-FOR-SMB General Moderate confidence

Benchmark Value

700 mg/kg
Thresholds: Lower: 700, Upper: —
Direction: Higher is desirable ↑
Form: LowerThreshold

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 LowerThreshold Guard Point Guard MinimumOnly Guard Point Guard OptimalRange Guard Point Guard MinimumOnly Guard OptimalRange Guard

Evidence & Context

Therefore, a loss of more than 50% of the MBC from the native reference benchmark likely represents a transition into a functionally degraded state. This would correspond to an MBC value below approximately 700 mg/kg.

Metric Definition:

Microbial Biomass Carbon (MBC) is the quantitative measure of the carbon mass contained within these living microorganisms.

Benchmark Definition:

This lower threshold indicates the Microbial Biomass Carbon level below which the soil ecosystem is likely functionally degraded in the temperate grassy woodlands and plains biome under production forestry land use in Australia.

Justification:

Inferred from the fact that conversion of native Australian ecosystems to agriculture has been shown to result in a loss of 40-60% of total SOC stocks, and MBC is the most active and sensitive component of SOC.

Sources (1)

Preview of A meta-analysis of soil microbial biomass responses to forest disturbances - PMC
A meta-analysis of soil microbial biomass responses to forest disturbances - PMC Journal

A meta-analysis of soil microbial biomass responses to forest disturbances - PMC, accessed August 10, 2025

View Source

Supporting Sources (24)

Additional references from the underlying research that informed this benchmark.

Preview of A meta-analysis of soil microbial biomass responses to forest disturbances - PMC, accessed August 28, 2025,
A meta-analysis of soil microbial biomass responses to forest disturbances - PMC, accessed August 28, 2025,
Contextual Support Journal

Selective logging impacts on soil microbial communities and functioning in Bornean tropical forest - Frontiers, accessed August 10, 2025

View Source
Preview of A review on effective soil health bio-indicators for ecosystem restoration and sustainability, accessed August 5, 2025,
A review on effective soil health bio-indicators for ecosystem restoration and sustainability, accessed August 5, 2025,
Contextual Support Journal

Microorganisms as Indicators of Soil Health, accessed August 10, 2025

View Source
Preview of Age and Species of Eucalyptus Plantations Affect Soil Microbial ...
Age and Species of Eucalyptus Plantations Affect Soil Microbial ...
Contextual Support Irrelevant Journal

Contrasting Soil pH Effects on Fungal and Bacterial Growth Suggest Functional Redundancy in Carbon Mineralization - PMC, accessed July 21, 2025

View Source
Preview of Australia's Framework of Criteria and Indicators - DAFF
Australia's Framework of Criteria and Indicators - DAFF
Contextual Support Journal

Australia's Framework of Criteria and Indicators - DAFF, accessed August 10, 2025

View Source
Preview of Australia's Framework of Criteria and Indicators - DAFF, accessed July 12, 2025,
Australia's Framework of Criteria and Indicators - DAFF, accessed July 12, 2025,
Contextual Support Journal

Australia's Framework of Criteria and Indicators - DAFF, accessed July 30, 2025,

View Source
Preview of ECOLOGICALLY SUSTAINABLE FOREST MANAGEMENT - Forestry Australia, accessed August 10, 2025,
ECOLOGICALLY SUSTAINABLE FOREST MANAGEMENT - Forestry Australia, accessed August 10, 2025,
Contextual Support Journal

www.forestry.org.au

View Source
Preview of Effects of Forest Types and Environmental Factors on Soil Microbial Biomass in a Coastal Sand Dune of Subtropical China - Journal of Resources and Ecology
Effects of Forest Types and Environmental Factors on Soil Microbial Biomass in a Coastal Sand Dune of Subtropical China - Journal of Resources and Ecology
Contextual Support Journal

Fungi to bacteria ratio: Historical misinterpretations and potential implications | Request PDF

View Source
Preview of Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org ...
Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org ...
Contextual Support Government

Microbial Biomass | Fact Sheets | soilquality.org.au

View Source
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 Microbial Biomass | Fact Sheets | soilquality.org.au
Microbial Biomass | Fact Sheets | soilquality.org.au
Contextual Support Government

Soil temperature, microbial biomass and enzyme activity are the critical factors affecting soil respiration in different soil layers in Ziwuling Mountains, China, accessed August 10, 2025

View Source
Preview of Microbiological Indicators for Assessing the Effects of Agricultural Practices on Soil Health: A Review - MDPI, accessed on June 5, 2025
Microbiological Indicators for Assessing the Effects of Agricultural Practices on Soil Health: A Review - MDPI, accessed on June 5, 2025
Contextual Support Journal

Unraveling the Importance of Forest Structure and Composition Driving Soil Microbial and Enzymatic Responses in the Subtropical Forest Soils - MDPI

View Source
Preview of Restoration of eucalypt grassy woodland: effects of experimental interventions on ground-layer vegetation - CSIRO PUBLISHING | Australian Journal of Botany, accessed August 12, 2025,
Restoration of eucalypt grassy woodland: effects of experimental interventions on ground-layer vegetation - CSIRO PUBLISHING | Australian Journal of Botany, accessed August 12, 2025,
Contextual Support Journal

Eucalypt woodlands Regrowth Benefits - Management Guideline - Queensland Government, accessed August 12, 2025

View Source
Preview of Reviews of High Priority Species for Woody Biomass Crops in Lower Rainfall Southern Australia - Enviro Data SA
Reviews of High Priority Species for Woody Biomass Crops in Lower Rainfall Southern Australia - Enviro Data SA
Contextual Support Journal

Reviews of High Priority Species for Woody Biomass Crops in Lower Rainfall Southern Australia - Enviro Data SA

View Source
Preview of Seasonal Dynamics of Soil Microbial Biomass C, N and P along an Altitudinal Gradient in Central Himalaya, India - MDPI, accessed August 28, 2025,
Seasonal Dynamics of Soil Microbial Biomass C, N and P along an Altitudinal Gradient in Central Himalaya, India - MDPI, accessed August 28, 2025,
Contextual Support Journal

The role of soil microbes in the global carbon cycle: tracking the below-ground microbial processing of plant-derived carbon for manipulating carbon dynamics in agricultural systems

View Source
Preview of Soil carbon sequestration in rangelands a critical review of the impacts of major management strategies - CSIRO Publishing, accessed August 5, 2025,
Soil carbon sequestration in rangelands a critical review of the impacts of major management strategies - CSIRO Publishing, accessed August 5, 2025,
Contextual Support Journal

Managing cattle grazing intensity: effects on soil organic matter and soil nitrogen, accessed July 23, 2025

View Source
Preview of Soil Carbon Sequestration Potential: A review for Australian ... - MLA
Soil Carbon Sequestration Potential: A review for Australian ... - MLA
Contextual Support Direct Evidence Journal

Soil Carbon Sequestration Potential: A review for Australian ... - MLA, accessed August 10, 2025

View Source
Preview of Soil carbon, nutrient, and microbial interactions in a phosphorus limited ecosystem exposed to elevated CO2 Johanna Pihlblad - Research Profiles and Repository - Western Sydney University
Soil carbon, nutrient, and microbial interactions in a phosphorus limited ecosystem exposed to elevated CO2 Johanna Pihlblad - Research Profiles and Repository - Western Sydney University
Contextual Support Journal

Soil carbon, nutrient, and microbial interactions in a phosphorus limited ecosystem exposed to elevated CO2 Johanna Pihlblad - Research Profiles and Repository - Western Sydney University, accessed August 10, 2025

View Source
Preview of Soil microbial biomass carbon and nitrogen in forest ecosystems of Northeast China: a comparison between natural secondary forest and larch plantation | Journal of Plant Ecology | Oxford Academic
Soil microbial biomass carbon and nitrogen in forest ecosystems of Northeast China: a comparison between natural secondary forest and larch plantation | Journal of Plant Ecology | Oxford Academic
Contextual Support Journal

Soil microbial biomass carbon and nitrogen in forest ecosystems of Northeast China: a comparison between natural secondary forest and larch plantation | Journal of Plant Ecology | Oxford Academic, accessed August 10, 2025

View Source
Preview of Soil microbial biomass carbon and nitrogen in forest ecosystems of Northeast China: a comparison between natural secondary forest and larch plantation | Journal of Plant Ecology | Oxford Academic, accessed August 28, 2025,
Soil microbial biomass carbon and nitrogen in forest ecosystems of Northeast China: a comparison between natural secondary forest and larch plantation | Journal of Plant Ecology | Oxford Academic, accessed August 28, 2025,
Contextual Support Journal

Drivers and trends of global soil microbial carbon over two decades - PMC, accessed August 28, 2025

View Source
Preview of Soil microbial biomass—what do the numbers really mean? - ResearchGate, accessed August 28, 2025,
Soil microbial biomass—what do the numbers really mean? - ResearchGate, accessed August 28, 2025,
Contextual Support GreyLiterature

Responses of soil labile organic carbon stocks and the carbon pool management index to different vegetation restoration types in the Danxia landform region of southwest China - PMC - PubMed Central

View Source
Preview of Soil microbial biomass, activity and community composition in adjacent native and plantation forests of subtropical Australia | Request PDF - ResearchGate
Soil microbial biomass, activity and community composition in adjacent native and plantation forests of subtropical Australia | Request PDF - ResearchGate
Contextual Support GreyLiterature

Soil water characteristics of a red chromosol and brown vertosol and ..., accessed May 19, 2025

View Source
Preview of Soil temperature, microbial biomass and enzyme activity are the critical factors affecting soil respiration in different soil layers in Ziwuling Mountains, China - PMC, accessed August 5, 2025,
Soil temperature, microbial biomass and enzyme activity are the critical factors affecting soil respiration in different soil layers in Ziwuling Mountains, China - PMC, accessed August 5, 2025,
Contextual Support Journal

Soil respiration rate and its sensitivity to temperature in pasture systems of dry-tropics - Taylor & Francis Online, accessed August 5, 2025

View Source
Preview of Srivastava, S. C., & Singh, J. S. (1989). Effect of cultivation on microbial biomass C and N of a dry tropical forest soil. Biology and Fertility of Soils, 8(4), 343-348.
Srivastava, S. C., & Singh, J. S. (1989). Effect of cultivation on microbial biomass C and N of a dry tropical forest soil. Biology and Fertility of Soils, 8(4), 343-348.
Contextual Support GreyLiterature

Soil microbial biomass, activity and community composition in adjacent native and plantation forests of subtropical Australia | Request PDF - ResearchGate

View Source
Preview of Woodlands - DCCEEW, accessed August 5, 2025,
Woodlands - DCCEEW, accessed August 5, 2025,
Contextual Support Government

Woodlands - DCCEEW, accessed August 4, 2025,

View Source

Context

  • Region Australia
  • Biome Temperate Grassy Woodlands & Plains
  • Land Use Production Forestry
  • Assessment Not Stated
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 27 May 2026

Notes

Represents a state of significant functional impairment (>50% loss from reference), where resilience and key nutrient cycling processes are likely compromised. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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

1409 mg/kg Moderate
Production Forestry · Pristine Reference · Forest
Point Active v1