Microbial Biomass Carbon (MBC)

AUS-TMI-FOR-SMB General Low confidence

Benchmark Value

No specific value — see range
Range: 240 to 400 mg/kg
Thresholds: Lower: 240, Upper: 400
Optimal Range: 240 to 400
Direction: Higher is desirable ↑
Form: OptimalRange

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 functional range for improvement is considered to be ~240–400 mg kg−1. Sites in this range are functional but have clear potential to improve through best-practice management.

Metric Definition:

Optimal functional range for Microbial Biomass Carbon indicating functional sites with potential for improvement

Benchmark Definition:

This benchmark represents the optimal functional range of microbial biomass carbon in tropical production forestry soils, indicating sites that are functional but can improve with best practices.

Justification:

Defined as the zone between the Lower Critical Threshold and the Best Available Condition Benchmark.

Sources (1)

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

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

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Preview of Topsoil microbial biomass carbon pool and the microbial quotient under distinct land-use types across China
Topsoil microbial biomass carbon pool and the microbial quotient under distinct land-use types across China
Direct Evidence GreyLiterature

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

View Source
Preview of Traditional Aboriginal and Torres Strait Islander Land Management Practices: Fire-Stick Farming and Beyond - Welcome To Country - Shop, accessed July 30, 2025
Traditional Aboriginal and Torres Strait Islander Land Management Practices: Fire-Stick Farming and Beyond - Welcome To Country - Shop, accessed July 30, 2025
Direct Evidence GreyLiterature

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

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Maritime Islands
  • Land Use Production Forestry
  • Assessment Not Stated
  • Evidence Type HealthyOperationalRange

Lifecycle

  • Status Active
  • Version 1
  • Effective From 5 Jun 2026

Notes

Sites within this range are considered ecologically functional but can improve through best practices. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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

400 mg/kg Low
Production Forestry · Not Stated
Point Active v1