Microbial Biomass Carbon (MBC)

AUS-TGP-CON-SMB General Moderate confidence

Benchmark Value

536 mg/kg

Range: 536 to 536 mg/kg

Optimal Range: 536 to 536

Direction: Higher is desirable ↑

Form: Point

Scoring Curve

Scoring curve unavailable

The scoring engine could not generate a curve for this benchmark context. The primary form is CompositeFramework, but the benchmark data may be missing required fields (e.g., optimal range bounds for an OptimalRange benchmark). This is typically a data quality issue in the benchmark pipeline.

Contributing Benchmarks

CompositeFramework Primary Point Guard LowerThreshold Guard Point Guard Point Guard OptimalRange Guard LowerThreshold Guard Point Guard OptimalRange Guard OptimalRange Guard

Evidence & Context

The recommended benchmark value is 536 mg/kg for topsoil (0–10 cm).

Metric Definition:

Microbial Biomass Carbon (MBC) in the topsoil (0–10 cm) of Australian Temperate Grassy Woodlands & Plains under conservation management.

Benchmark Definition:

This benchmark represents the best available condition of soil microbial biomass carbon achievable in temperate grassy woodlands and plains under conservation management in Australia.

Justification:

This value is derived from a comprehensive global meta-analysis for the temperate broadleaf forest biome, which serves as the most appropriate available proxy for Australian temperate grassy woodlands. This value is corroborated by independent Australian studies showing similar MBC levels in high-carbon temperate pasture soils.

Sources (4)

A global analysis of soil microbial biomass carbon, nitrogen and phosphorus in terrestrial ecosystems

Soil Carbon Sequestration Potential: A review for Australian agriculture - MLA, accessed August 3, 2025

View Source

Preview of grazing impacts on the spatial distribution of soil microbial biomass around tussock grasses in a tropical grassland - Publication : USDA ARS

grazing impacts on the spatial distribution of soil microbial biomass around tussock grasses in a tropical grassland - Publication : USDA ARS Journal

Soil microbial community structure is unaltered by grazing intensity and plant species richness in a temperate grassland steppe in northern China - Publication : USDA ARS, accessed July 29, 2025

View Source

Preview of Microbial biomass and microbial biodiversity in some soils from New South Wales, Australia - CSIRO PUBLISHING | Soil Research

Microbial biomass and microbial biodiversity in some soils from New South Wales, Australia - CSIRO PUBLISHING | Soil Research Journal

Microbial biomass and microbial biodiversity in some soils from New South Wales, Australia - CSIRO PUBLISHING | Soil Research, accessed August 12, 2025

View Source

Preview of Restoring ecological function in temperate grassy woodlands: Manipulating soil nutrients, exotic annuals and native perennial grasses through carbon supplements and spring burns | Request PDF - ResearchGate, accessed May 12, 2025

Restoring ecological function in temperate grassy woodlands: Manipulating soil nutrients, exotic annuals and native perennial grasses through carbon supplements and spring burns | Request PDF - ResearchGate, accessed May 12, 2025 Journal

Increasing and declining native species in urban remnant grasslands respond differently to nitrogen addition and disturbance, accessed May 19, 2025,

View Source

Context

Region Australia
Biome Temperate Grassy Woodlands & Plains
Land Use Conservation / Protected Natural Areas
Assessment Conservation Target
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 17 Mar 2026

Notes

No upper detrimental threshold for MBC exists, but abnormally high levels can indicate nutrient pollution (eutrophication) favoring invasive species. A lower critical threshold is functionally represented by a >70% decline from the benchmark (~160 mg/kg). An optimal state is characterized by MBC levels approaching this benchmark with a high microbial quotient (MBC:SOC>2%) and a resilient native plant community.

Related Benchmarks

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