Ground Cover - Tree Canopy

AUS-TGP-FOR-TCC General Moderate confidence

Benchmark Value

40 %

Direction: Lower is desirable ↓

Form: MaximumOnly

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 OptimalRange Guard LowerThreshold Guard UpperThreshold Guard OptimalRange Guard Point Guard MinimumOnly Guard MaximumOnly Guard Point Guard

Evidence & Context

Multiple studies focusing on the critical relationship between the overstorey and understorey provide a consistent threshold. They show that as TCC increases beyond 30% to 40%, there is a rapid and significant loss of species richness and cover in the light-dependent grassy and herbaceous ground layer.

Metric Definition:

Tree Canopy Cover (TCC) as the percentage of ground covered by tree canopy in Temperate Grassy Woodlands.

Benchmark Definition:

This benchmark marks the maximum tree canopy cover above which significant ecological degradation occurs due to loss of understorey biodiversity.

Justification:

Exceeding 40% TCC leads to significant ecological degradation through woodland thickening.

Sources (1)

Preview of Bioregions and EVC benchmarks - Environment, accessed August 5, 2025,

Bioregions and EVC benchmarks - Environment, accessed August 5, 2025, Government

TASVEG VCA Manual: A manual for assessing vegetation condition in Tasmania, Version 2.0. Natural and Cultural Heritage, Department of

View Source

Context

Region Australia
Biome Temperate Grassy Woodlands & Plains
Land Use Production Forestry
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 10 Jun 2026

Notes

This threshold marks the onset of a degraded state with loss of understorey biodiversity. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

Other benchmarks in the AUS-TGP-FOR-TCC family.