Microbial Biomass Carbon (MBC)

AUS-ASC-CON-SMB General Moderate confidence

Benchmark Value

2240 mg/kg

Range: 1500 to 4500 mg/kg

Optimal Range: 1500 to 4500

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

Contributing Benchmarks

OptimalRange Primary Point Guard Point Guard

Evidence & Context

Reference Value: A Microbial Biomass Carbon (MBC) value of 2240 mg/kg is identified as the reference benchmark for the best available condition in Australian Alpine and Subalpine protected natural areas.

Metric Definition:

Microbial Biomass Carbon (MBC) within the topsoil (0–10 cm)

Benchmark Definition:

This benchmark represents the reference value of Microbial Biomass Carbon (MBC) in the topsoil of Australian Alpine and Subalpine protected natural areas, indicating a high ecological function state.

Justification:

This value is derived from the strong, positive correlation between Soil Organic Carbon (SOC) and MBC, using a proxy-based methodology due to lack of direct field measurements.

Sources (1)

Preview of Microbe Biomass in Relation to Organic Carbon and Clay in Soil - ResearchGate

Microbe Biomass in Relation to Organic Carbon and Clay in Soil - ResearchGate

Microbe Biomass in Relation to Organic Carbon and Clay in Soil - ResearchGate, accessed August 28, 2025,

Supporting Sources (25)

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,

Meta Analysis Journal

Selective logging impacts on soil microbial communities and functioning in Bornean tropical forest - Frontiers

Preview of Alpine soils in Australia with reference to conditions in Europe and New Zealand, accessed August 28, 2025,

Alpine soils in Australia with reference to conditions in Europe and New Zealand, accessed August 28, 2025,

Contextual Support Journal

Alpine soils in Australia with reference to conditions in Europe and New Zealand, accessed August 3, 2025,

Preview of Australian Soil Classification Map - TERN Data Discovery Portal, accessed August 28, 2025,

Australian Soil Classification Map - TERN Data Discovery Portal, accessed August 28, 2025,

Contextual Support Government

Australian Soil Classification Map - TERN Data Discovery Portal, accessed May 27, 2025,

Preview of Biolo gy - Amazon S3, accessed August 28, 2025,

Biolo gy - Amazon S3, accessed August 28, 2025,

Contextual Support Journal

Biolo gy - Amazon S3, accessed August 28, 2025,

Preview of Changes in Soil Microbial Community Structure and Function in an Alpine Dry Meadow Following Spring Snow Melt - ResearchGate, accessed August 28, 2025,

Changes in Soil Microbial Community Structure and Function in an Alpine Dry Meadow Following Spring Snow Melt - ResearchGate, accessed August 28, 2025,

Contextual Support Journal

Changes in Soil Microbial Community Structure and Function in an Alpine Dry Meadow Following Spring Snow Melt - ResearchGate, accessed August 28, 2025,

Preview of Comparison of methods to quantify soil microbial biomass carbon - SciELO, accessed August 28, 2025,

Comparison of methods to quantify soil microbial biomass carbon - SciELO, accessed August 28, 2025,

Methodology Source Journal

Comparison of methods to quantify soil microbial biomass carbon - SciELO, accessed August 28, 2025,

Preview of Distribution, nature and threats to soils of the Australian Alps: A review - ResearchGate, accessed August 28, 2025,

Distribution, nature and threats to soils of the Australian Alps: A review - ResearchGate, accessed August 28, 2025,

Contextual Support

Distribution, nature and threats to soils of the Australian Alps: A ...

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

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

Contextual Support Journal

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

Preview of Driving Factors That Reduce Soil Carbon, Sugar, and Microbial Biomass in Degraded Alpine Grasslands - UA Campus Repository, accessed August 28, 2025,

Driving Factors That Reduce Soil Carbon, Sugar, and Microbial Biomass in Degraded Alpine Grasslands - UA Campus Repository, accessed August 28, 2025,

Contextual Support Journal

Driving Factors That Reduce Soil Carbon, Sugar, and Microbial Biomass in Degraded Alpine Grasslands - UA Campus Repository, accessed August 28, 2025,

Preview of Global Climate Change Effects on Soil Microbial Biomass Stoichiometry in Alpine Ecosystems - MDPI, accessed August 28, 2025,

Global Climate Change Effects on Soil Microbial Biomass Stoichiometry in Alpine Ecosystems - MDPI, accessed August 28, 2025,

Contextual Support Journal

Global Climate Change Effects on Soil Microbial Biomass Stoichiometry in Alpine Ecosystems - MDPI, accessed on June 5, 2025

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 Government

Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org.au, accessed July 18, 2025,

Preview of Microbe Biomass in Relation to Organic Carbon and Clay in Soil - MDPI, accessed August 28, 2025,

Microbe Biomass in Relation to Organic Carbon and Clay in Soil - MDPI, accessed August 28, 2025,

Contextual Support Journal

Trends in Microbial Community Composition and Function by Soil Depth - PMC

Preview of Microbial Biomass Carbon - NSW | Fact Sheets | soilquality.org.au, accessed August 5, 2025,

Microbial Biomass Carbon - NSW | Fact Sheets | soilquality.org.au, accessed August 5, 2025,

Contextual Support GreyLiterature

Microbial Biomass | Fact Sheets | soilquality.org.au, accessed July 18, 2025,

Preview of Microbial biomass Carbon, Nitrogen, and Phosphorus dynamics along a chronosequence of abandoned tropical agroecosystems, accessed August 28, 2025,

Microbial biomass Carbon, Nitrogen, and Phosphorus dynamics along a chronosequence of abandoned tropical agroecosystems, accessed August 28, 2025,

Contextual Support Journal

Microbial biomass Carbon, Nitrogen, and Phosphorus dynamics along a chronosequence of abandoned tropical agroecosystems, accessed August 28, 2025,

Preview of Microbial communities and activities in alpine and subalpine soils | FEMS Microbiology Ecology | Oxford Academic, accessed August 28, 2025,

Microbial communities and activities in alpine and subalpine soils | FEMS Microbiology Ecology | Oxford Academic, accessed August 28, 2025,

Contextual Support Journal

Microbial communities and activities in alpine and subalpine soils | FEMS Microbiology Ecology | Oxford Academic, accessed August 28, 2025,

Preview of Nitrogen dynamics in alpine soils of south ... - CSIRO Publishing, accessed August 28, 2025,

Nitrogen dynamics in alpine soils of south ... - CSIRO Publishing, accessed August 28, 2025,

Contextual Support Journal

Nitrogen dynamics in alpine soils of south-eastern Australia - CSIRO Publishing

Preview of Predicting and regulating soil carbon in a warmer world | TERN Australia, accessed August 28, 2025,

Predicting and regulating soil carbon in a warmer world | TERN Australia, accessed August 28, 2025,

Contextual Support Government

Department of Natural Resources and Environment Tasmania. (2025). Tasmanian High Soil Carbon Landscapes project.

Preview of Ratio of microbial biomass carbon to soil organic carbon as a sensitive indicator of changes in soil organic matter - CSIRO PUBLISHING | Soil Research, accessed August 28, 2025,

Ratio of microbial biomass carbon to soil organic carbon as a sensitive indicator of changes in soil organic matter - CSIRO PUBLISHING | Soil Research, accessed August 28, 2025,

Contextual Support Journal

Ratio of microbial biomass carbon to soil organic carbon as a sensitive indicator of changes in soil organic matter - CSIRO PUBLISHING | Soil Research, accessed August 28, 2025,

Preview of Reduced microbial stability in the active layer is associated with carbon loss under alpine permafrost degradation | PNAS, accessed August 28, 2025,

Reduced microbial stability in the active layer is associated with carbon loss under alpine permafrost degradation | PNAS, accessed August 28, 2025,

Contextual Support

Reduced microbial stability in the active layer is associated with carbon loss under alpine permafrost degradation | PNAS, accessed August 28, 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

Fact Sheets Biological Indicators - Soil Quality

Preview of Soil microbial biomass and organic carbon - Eurofins, accessed August 28, 2025,

Soil microbial biomass and organic carbon - Eurofins, accessed August 28, 2025,

Contextual Support Journal

Soil Microbial Biomass: A Crucial Indicator of Soil Health, accessed July 18, 2025,

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

Forests and Decarbonization – Roles of Natural and Planted Forests - Frontiers

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

Soil microbial biomass carbon and CO2? - ResearchGate, accessed July 18, 2025,

Preview of theaustralianalpsnationalparks.org, accessed on May 25, 2025,

theaustralianalpsnationalparks.org, accessed on May 25, 2025,

Contextual Support Journal

theaustralianalpsnationalparks.org

Preview of theaustralianalpsnationalparks.org, accessed on May 29, 2025,

theaustralianalpsnationalparks.org, accessed on May 29, 2025,

Contextual Support Journal

Maximising Plant Growth: The Importance of Potassium Fertiliser - Plant Needs Pty. Ltd., accessed May 28, 2025,

Context

Region Australia
Biome Alpine and Subalpine Complex
Land Use Conservation / Protected Natural Areas
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 16 Mar 2026

Notes

No direct field measurements for MBC in Australian alpine conservation areas were found. The benchmark represents a state of high ecological function within the optimal range of 1500–4500 mg/kg. No evidence was found for a detrimental upper threshold in this natural ecosystem.