Microbial Biomass Carbon (MBC)

AUS-TDG-FOR-SMB General Moderate confidence

Benchmark Value

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

Evidence & Context

The reference value of 600 mg/kg is an indicative target for best-practice Production Forestry in Australian Temperate Dry Woodlands & Native Grasslands (0-10 cm topsoil), aiming for high environmental health.

Metric Definition:

Microbial Biomass Carbon (MBC) is a key indicator of soil health, representing the total carbon held within the cells of living microorganisms, primarily bacteria and fungi, in the soil.

Benchmark Definition:

This benchmark represents an indicative target value for Microbial Biomass Carbon in the top 0-10 cm of soil under best-practice Production Forestry in Australian Temperate Dry Woodlands & Native Grasslands, aiming to maintain high soil health and biological activity.

Justification:

This value is inferred due to a lack of direct empirical data for this specific land use and biome under "best-on-offer" sustainable management in Australia. It is based on the upper range of MBC observed in healthy, productive temperate grassland ecosystems and the principle that sustainable forestry should maintain soil health comparable to healthy native systems.

Sources (1)

Preview of Temperate forests and soils [Chapter 6], accessed August 10, 2025,

Temperate forests and soils [Chapter 6], accessed August 10, 2025,

A review of the potential impacts of different fire regimes on soil erosion and sedimentation, nutrient and carb

Supporting Sources (22)

Additional references from the underlying research that informed this benchmark.

Preview of Adams, M, accessed on June 7, 2025,

Adams, M, accessed on June 7, 2025,

Contextual Support Journal

Adams, M, accessed on June 7, 2025,

Preview of An ensemble estimate of Australian soil organic ... - EGUsphere, accessed on June 7, 2025,

An ensemble estimate of Australian soil organic ... - EGUsphere, accessed on June 7, 2025,

Contextual Support Journal

An ensemble estimate of Australian soil organic carbon using machine learning and process-based modelling - EGUsphere

Preview of Carbon | Australia state of the environment 2021, accessed on June 7, 2025,

Carbon | Australia state of the environment 2021, accessed on June 7, 2025,

Contextual Support Government

CO₂ sink to source: Arid Australia's climate and rainfall driven tipping points

Preview of Climatic, Edaphic and Biotic Controls over Soil δ13C and δ15N in ...

Climatic, Edaphic and Biotic Controls over Soil δ13C and δ15N in ...

Contextual Support Journal

Climatic, Edaphic and Biotic Controls over Soil δ13C and δ15N in ..., accessed on June 7, 2025,

Preview of Effect of vegetation type and season on microbial biomass carbon in Central Himalayan forest soils, India - The Commonwealth Scientific and Industrial Research Organisation (CSIRO) - Discovery, accessed on June 7, 2025,

Effect of vegetation type and season on microbial biomass carbon in Central Himalayan forest soils, India - The Commonwealth Scientific and Industrial Research Organisation (CSIRO) - Discovery, accessed on June 7, 2025,

Contextual Support Journal

Organic matter characteristics under native forest, long-term pasture, and recent conversion to Eucalyptus plantations in Western Australia: microbial biomass, soil respiration, and permanganate oxidation - CSIRO Publishing, accessed on June 7, 2025,

Preview of Effects of heavy metals on soil microbial biomass carbon - ResearchGate, accessed on June 7, 2025,

Effects of heavy metals on soil microbial biomass carbon - ResearchGate, accessed on June 7, 2025,

Direct Evidence Journal

Variation in soil microbial biomass in the dry tropics: impact of land-use change, accessed on June 7, 2025,

Preview of Effects of Management Practices on Soil Microbial Diversity and ..., accessed on June 7, 2025,

Effects of Management Practices on Soil Microbial Diversity and ..., accessed on June 7, 2025,

Contextual Support Journal

Effects of Management Practices on Soil Microbial Diversity and Structure on Eucalyptus Plantations - MDPI

Preview of Environment Monitoring Systems & Data for Ecosystem Studies ..., accessed July 30, 2025,

Environment Monitoring Systems & Data for Ecosystem Studies ..., accessed July 30, 2025,

Contextual Support Government

(PDF) Evaluation of genetic markers for the metabarcoding of ...

Preview of Grazing-management-for-soil-carbon-in-Australia-A-review.pdf - University of Tasmania, accessed on June 7, 2025,

Grazing-management-for-soil-carbon-in-Australia-A-review.pdf - University of Tasmania, accessed on June 7, 2025,

Contextual Support Journal

www.utas.edu.au, accessed May 11, 2025

Preview of Heat input determines the response and rapid recovery of post-fire soil microbial biomass - CSIRO PUBLISHING | International Journal of Wildland Fire, accessed on June 7, 2025,

Heat input determines the response and rapid recovery of post-fire soil microbial biomass - CSIRO PUBLISHING | International Journal of Wildland Fire, accessed on June 7, 2025,

Contextual Support Journal

Increased microbial growth, biomass, and turnover drive soil organic carbon accumulation at higher plant diversity - PMC - PubMed Central, accessed on June 7, 2025,

Preview of Impacts of management and changed hydrology on soil microbial communities in a floodplain forest, accessed on June 7, 2025,

Impacts of management and changed hydrology on soil microbial communities in a floodplain forest, accessed on June 7, 2025,

Contextual Support Journal

Thermal sensitivity of soil microbial carbon use efficiency across forest biomes - PMC, accessed on June 7, 2025,

Preview of Increased microbial growth, biomass, and turnover drive soil organic carbon accumulation at higher plant diversity - PMC - PubMed Central, accessed on June 7, 2025,

Increased microbial growth, biomass, and turnover drive soil organic carbon accumulation at higher plant diversity - PMC - PubMed Central, accessed on June 7, 2025,

Contextual Support Journal

Temperate forests and soils [Chapter 6], accessed on June 7, 2025,

Lifting the Profile of Deep Forest Soil Carbon - MDPI, accessed on June 7, 2025,

Contextual Support Journal

Lifting the Profile of Deep Forest Soil Carbon - MDPI, accessed on June 7, 2025,

Preview of Microbial Biomass - Qld | Fact Sheets | soilquality.org.au

Microbial Biomass - Qld | Fact Sheets | soilquality.org.au

Contextual Support GreyLiterature

Global negative effects of nitrogen deposition on soil microbes - PMC, accessed July 31, 2025

Preview of Models for the Sustainable Management of Temperate Plantation Forests - ResearchGate, accessed on June 7, 2025,

Models for the Sustainable Management of Temperate Plantation Forests - ResearchGate, accessed on June 7, 2025,

Contextual Support GreyLiterature

Adams, M, accessed on June 7, 2025,

Preview of Organic matter characteristics under native forest, long-term pasture, and recent conversion to Eucalyptus plantations in Western Australia: microbial biomass, soil respiration, and permanganate oxidation - CSIRO Publishing, accessed on June 7, 2025,

Organic matter characteristics under native forest, long-term pasture, and recent conversion to Eucalyptus plantations in Western Australia: microbial biomass, soil respiration, and permanganate oxidation - CSIRO Publishing, accessed on June 7, 2025,

Contextual Support Journal

Organic matter characteristics under native forest, long-term pasture, and recent conversion to Eucalyptus plantations in Western Australia: microbial biomass, soil respiration, and permanganate oxidation - CSIRO Publishing, accessed on June 7, 2025,

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

Preview of SOIL CARBON CONTENT AND MICROBIAL BIOMASS ACTIVITY OF DIFFERENT FOREST TYPES UNDER SEASONAL VARIATIONS - IJNRD, accessed on June 7, 2025,

SOIL CARBON CONTENT AND MICROBIAL BIOMASS ACTIVITY OF DIFFERENT FOREST TYPES UNDER SEASONAL VARIATIONS - IJNRD, accessed on June 7, 2025,

Contextual Support Journal

SOIL CARBON CONTENT AND MICROBIAL BIOMASS ACTIVITY OF DIFFERENT FOREST TYPES UNDER SEASONAL VARIATIONS - IJNRD, accessed on June 7, 2025,

Preview of Soil Carbon Pool as Influenced by Soil Microbial Activity—An Overview, accessed on June 7, 2025,

Soil Carbon Pool as Influenced by Soil Microbial Activity—An Overview, accessed on June 7, 2025,

Contextual Support Journal

Soil Carbon Pool as Influenced by Soil Microbial Activity—An Overview

Preview of Soil microbiome and biodiversity implications – are we ignoring cost-effective proxies of biodiversity measures? | TERN Australia, accessed on June 7, 2025,

Soil microbiome and biodiversity implications – are we ignoring cost-effective proxies of biodiversity measures? | TERN Australia, accessed on June 7, 2025,

Contextual Support GreyLiterature

Environment Monitoring Systems & Data for Ecosystem Studies ...

Preview of Thermal sensitivity of soil microbial carbon use efficiency across forest biomes - PMC, accessed on June 7, 2025,

Thermal sensitivity of soil microbial carbon use efficiency across forest biomes - PMC, accessed on June 7, 2025,

Contextual Support Journal

Thermal sensitivity of soil microbial carbon use efficiency across forest biomes - PMC, accessed on June 7, 2025,

Preview of Variation in soil microbial biomass in the dry tropics: impact of land-use change, accessed on June 7, 2025,

Variation in soil microbial biomass in the dry tropics: impact of land-use change, accessed on June 7, 2025,

Contextual Support Journal

Soil microbial biomass during the early establishment of hoop pine ...

Context

Region Australia
Biome Temperate Dry Woodlands & Native Grasslands
Land Use Production Forestry
Assessment Not Stated
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 3 Jun 2026

Notes

Lower Critical Threshold: Not numerically defined in reviewed literature for this specific context. Conceptually, levels significantly below those of healthy native ecosystems would indicate impaired soil function and unsustainable practices. Optimal Range: Not numerically defined. Would reflect MBC levels supporting robust ecosystem functioning and sustained productivity. Upper Detrimental Threshold: No evidence suggests an upper detrimental threshold for MBC itself under best-practice sustainable forestry; more is generally better up to natural saturation points. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.