Soil pH — Benchmark Detail

Benchmark Value

No specific value — see range

Range: 5.5 to 7 pH

Thresholds: Lower: 5.5, Upper: —

Optimal Range: 5.5 to 7

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.

Evidence & Context

The measured soil pH within this profile was slightly acidic, ranging from pH 5.5 to 6.5.

Metric Definition:

Soil pH measured in water from a plastic, clayey mineral soil profile within a high-integrity, relatively undisturbed mossy cloud forest on the summit of Mt Gower, Lord Howe Island.

Benchmark Definition:

This benchmark represents the typical soil pH range of slightly acidic volcanic soils in a high-integrity conservation area within the Tropical & Subtropical Maritime Islands biome in Australia.

Justification:

This benchmark is based on a peer-reviewed study of a specific soil profile in a high-integrity conservation area (Mt Gower cloud forest), representing a stable, well-functioning ecosystem on volcanic-derived soils.

Supporting Sources (4)

Additional references from the underlying research that informed this benchmark.

Floristics and structure of the mossy cloud forest of Mt Gower summit, Lord Howe Island

Direct Evidence Journal

Norfolk Island Pine Production Guide

View Source

Norfolk Island Region Threatened Species Recovery Plan

Direct Evidence

Norfolk Island Region Threatened Species Recovery Plan

View Source

Norfolk Island Region Threatened Species Recovery Plan

Direct Evidence

Norfolk Island Region Threatened Species Recovery Plan

Norfolk Island Region Threatened Species Recovery Plan

Direct Evidence

Norfolk Island Region Threatened Species Recovery Plan

Context

Region Australia
Biome Tropical & Subtropical Maritime Islands
Land Use Conservation / Protected Natural Areas
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Superseded
Version 1
Effective From 10 Mar 2026
Effective To 13 Mar 2026

Notes

Lower Critical Threshold: 5.5 pH. No upper detrimental threshold — higher values are always better up to natural saturation. A single benchmark for the entire biome is scientifically indefensible due to geological differences. Volcanic soils have pH 5.5-6.5, while calcareous soils are naturally alkaline (pH >8.0). [Migration] Original wider evidence range: 5.5 – 6.5 (retained OptimalRange: 5.5 – 7)

Related Benchmarks

Other benchmarks in the AUS-TMI-CON-SPH family.