Microbial Biomass Carbon (MBC)

AUS-ASC-CON-SMB General Moderate confidence

Benchmark Value

2240 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

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 typical Microbial Biomass Carbon (MBC) level in the topsoil (0–10 cm) of pristine Alpine and Subalpine conservation areas in Australia, indicating healthy soil microbial communities.

Justification:

The benchmark is derived from a proxy-based methodology using the strong positive correlation between Soil Organic Carbon (SOC) and MBC, anchored by a reference SOC value of 9.0% representing high environmental health in Alpine Humus Soils, and supported by empirical data from a comparable high-carbon temperate system.

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, accessed August 10, 2025

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 GreyLiterature

NSW Department of Primary Industries. (2021). Soil acidity and liming. Soils Guides.

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

Microbial biomass Carbon, Nitrogen, and Phosphorus dynamics along a chronosequence of abandoned tropical agroecosystems, 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 GreyLiterature

REPORT ON THE INVESTIGATION INTO THE FUTURE OF CATTLE GRAZING IN THE ALPINE NATIONAL PARK

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

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

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

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

Forest Soil Microbiomes: A Review of Key Research from 2003 to 2023 - MDPI

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

www.soilquality.org.au

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

Biolo gy - Amazon S3, 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

Five-year measurement data along a 1200 m elevational gradient reveals that global warming increases soil respiration - Frontiers

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

Fact Sheets Soil Organic Carbon Storage in the Western Avon Basin - WA

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

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 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

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

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

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

theaustralianalpsnationalparks.org, accessed on May 25, 2025,

Contextual Support Journal

Phosphorus Nutrition of Proteaceae in Severely Phosphorus-Impoverished Soils: Are There Lessons To Be Learned for Future Crops? - PubMed Central

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

theaustralianalpsnationalparks.org, accessed on May 29, 2025,

Contextual Support Journal

Soil Conservation in Alpine Catchments - The Kosciuszko Huts Association, accessed August 17, 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 1 Jun 2026

Notes

No direct field measurements for MBC in Australian alpine conservation areas were found; the benchmark is proxy-derived. The optimal range is 1500–4500 mg/kg, with no evidence of an upper detrimental threshold in this natural ecosystem. A significant sustained decline from 2240 mg/kg indicates ecosystem degradation.