Basal Area

AUS-TSR-CON-BAS General Moderate confidence

Benchmark Value

28 m²/ha
Direction: Higher is desirable ↑
Form: MinimumOnly

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

Evidence & Context

A basal area in the range of 25–28 m²/ha can be confidently identified as a critical lower boundary. An ecosystem dropping below this threshold is demonstrably degraded, its ecological resilience is compromised, and its capacity to support the full suite of native biodiversity and ecosystem functions is significantly diminished.

Metric Definition:

Stand basal area as the sum of cross-sectional areas of living tree stems ≥10 cm DBH per hectare.

Benchmark Definition:

This benchmark defines the critical lower basal area threshold below which tropical and subtropical rainforest structure and function are compromised, indicating ecosystem degradation.

Justification:

Long-term logging recovery studies show forests with basal area below ~28 m²/ha fail to recover structurally and functionally, indicating degradation.

Sources (1)

Preview of Patterns of basal area increment, mortality and recruitment were ..., accessed July 20, 2025,
Patterns of basal area increment, mortality and recruitment were ..., accessed July 20, 2025, Journal

Patterns of basal area increment, mortality and recruitment were related to logging intensity in subtropical rainforest in Australia over 35 years | Request PDF - ResearchGate

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Supporting Sources (4)

Additional references from the underlying research that informed this benchmark.

Preview of CSIRO Permanent Rainforest Plots of North Queensland, accessed July 20, 2025,
CSIRO Permanent Rainforest Plots of North Queensland, accessed July 20, 2025,
Direct Evidence Government

CSIRO Permanent Rainforest Plots of North Queensland

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Preview of Lowland Rainforest of Subtropical Australia ecological community - conservation advice
Lowland Rainforest of Subtropical Australia ecological community - conservation advice
Contextual Support Government

Lowland Rainforest of Subtropical Australia ecological community - conservation advice

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Preview of Lowland Rainforest of Subtropical Australia ecological community - listing advice
Lowland Rainforest of Subtropical Australia ecological community - listing advice
Contextual Support Journal

Lowland Rainforest of Subtropical Australia ecological community - listing advice

View Source
Preview of Stand basal area, accessed July 12, 2025,
Stand basal area, accessed July 12, 2025,
Contextual Support

Vegetation and floristics of a lowland tropical rainforest in northeast Australia - Biodiversity Data Journal

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Context

  • Region Australia
  • Biome Tropical & Subtropical Rainforests
  • Land Use Conservation / Protected Natural Areas
  • Assessment Pristine Reference
  • Vegetation Forest
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 7 Jun 2026

Notes

This threshold marks the point of diminishing returns for recovery and structural simplification leading to functional losses.