Allowing Mountain Ash to reach old-growth is one of the most effective ways to secure carbon, mitigate climate change, and maintain the ecological integrity of the Strzelecki Ranges. 

The Strzelecki Ranges are home to some of the world’s most remarkable and endangered forests. Towering Mountain Ash communities (Eucalyptus regnans) are not just breathtaking—they store more carbon than any other forest type on Earth, and are sadly lised as critically endangered according to the IUCN Red list of ecosystems.

A 50-year-old Mountain Ash forest already holds around 380 tonnes of carbon per hectare. But if allowed to grow into old-growth, that figure can exceed 1,000 tonnes. Across 10,000 hectares, that’s an extra 6.6 million tonnes of carbon locked away—equal to over 24 million tonnes of CO₂ emissions avoided.

Replacing these Strzelecki Mountain ash forests with short-rotation pine plantations would store only about 132 tonnes per hectare—a loss from the forest of more than two-thirds of the carbon. Repeated harvesting also releases soil carbon and reduces the forest’s long-term ability to store it.

Old-growth Mountain Ash forests act as stable, long-term carbon sinks, while providing clean water, habitat for threatened species, (like our Gang-gangs) and natural climate protection. In contrast, pine plantations  come at huge ecological and climatic cost.

Protecting these forests is not just an environmental choice; it is a practical climate strategy. Allowing Mountain Ash to reach old-growth is one of the most effective ways to secure carbon, mitigate climate change, and maintain the ecological integrity of the Strzelecki Ranges. 

We support FSC’s position that native species should not be replanted with exotic species such as pines. 

Carbon calculations are our best estimates - for full details of calculations and assumptions visit our website.

Images from Critical Ecological Roles, Structural Attributes and Conservation of Old Growth Forest: Lessons From a Case Study of Australian Mountain Ash Forests David Lindenmayer* and Elle Bowd

Calculations and Assumptions

Summary

Total Carbon Stored in the landscape 

Old growth 25year old Mountain ash - 1045 T/Ha

50 year old Mountains ash     - 370 T/Ha

25 year old Bluegum -159 T/Ha

25 year old Radiata Pine -132 T/Ha

Here’s a practical estimate and how I derived it, given a 50-year regenerating Mountain Ash (Eucalyptus regnans) stand in the Strzelecki Ranges (≈1100 mm rainfall, ≈300 m elevation)

Above-ground woody carbon (trees, large branches, standing dead)

Estimate: 200 to 350 t C per hectare

Best-guess (central) value: 275 t C/ha

Rationale: mountain ash forests are among the highest carbon-density eucalypt forests in Victoria; regrowing stands at 50 years will be well below old-growth maxima but still substantial. See published regional ranges for mountain ash carbon densities.  

Below-ground woody carbon (coarse and fine roots)

Estimate: 40 to 70 t C per hectare

Best-guess value: 55 t C/ha

Rationale: applied an IPCC / FAO relevant root:shoot ratio for eucalypt forests/plantations (roughly 0.2–0.35 depending on biomass class) to the aboveground estimate to get below ground woody biomass expressed as carbon.  

Soil organic carbon (top 0–30 cm)

Estimate: 30 to 80 t C per hectare

Best-guess value: 50 t C/ha

Rationale: temperate forest soils in high-rainfall parts of Victoria commonly hold tens of tonnes C/ha in the upper soil profile; national and regional studies show wide spatial variation so a broad range is appropriate.  

Total above + below ground carbon (trees + roots + topsoil 0–30 cm)

Estimate: 270 to 500 t C per hectare

Best-guess total: 380 t C/ha

Calculation used: Best-guess total = 275 (AGB) + 55 (roots) + 50 (soil) = 380 t C/ha

Key assumptions and uncertainties

Aboveground asymptote set to 500 t C/ha for mountain ash mature forest; growth curve chosen to pass through 275 t C/ha at 50 years. Root:shoot ratio assumed 0.20. Soil carbon assumed 50 t C/ha (0–30 cm) and constant. Disturbance (fire, salvage logging, drought, insect outbreaks), site fertility, stocking density, prior land use, and soil depth/profile can all change these numbers substantially. Uncertainty is large; plausible total-average ranges might be roughly 300–450 t C/ha depending on those factors.

Pines

Summary estimate for a 25-year rotation Pinus radiata plantation in the same location (Strzelecki Ranges, ~1100 mm rainfall, ~300 m elevation), expressed as tonnes of carbon per hectare averaged across the landscape over 100 years

Best-guess average (mean over repeated 25-year rotations across 100 years): 132 t C/ha

Range (plausible low to high): 96 to 169 t C/ha

Total mean landscape C = mean AGB + mean roots + soil C

Low case = 55 + 11 + 30 = 96 t C/ha

Best case = 77 + 15.4 + 40 = 132.4 ≈ 132 t C/ha

High case = 99 + 19.8 + 50 = 168.8 ≈ 169 t C/ha

Notes and important caveats

These numbers are for carbon stored within the ecosystem (standing trees + roots + topsoil 0–30 cm) only. They do not include carbon transferred to harvested wood products, landfill, or long-lived product pools after harvest. Including durable harvested-wood-carbon (HWP) would raise the total landscape carbon retained over 100 years depending on product mix and HWP decay assumptions.

Soil carbon under plantations can change slowly over multiple rotations (small declines or gains depending on previous land use and management); I assumed it stays roughly constant. If soils lose carbon under repeated rotations, the totals above could be lower by tens of t C/ha.

For an old-growth Mountain Ash (Eucalyptus regnans) forest in the Strzelecki Ranges (~1100 mm rainfall, 300 m elevation), approaching 300 years or within 95% of its maximum biomass, carbon storage is extremely high compared with regenerating or younger stands.

Aboveground woody carbon (trees, large branches, standing dead)

Old-growth tall Mountain Ash can reach 600–1000 t C/ha in aboveground biomass. Best estimate: ~800 t C/ha. These forests accumulate enormous woody biomass because E. regnans grows very tall (>80 m), with massive DBH, and develops many large trees per hectare.

Belowground woody carbon (roots)

Applying a root:shoot ratio of ~0.2–0.25 gives 160–200 t C/ha in roots. Best estimate: ~180 t C/ha.

Soil organic carbon

(0–30 cm)

Temperate forest soils under long-unlogged Mountain Ash typically contain 50–80 t C/ha in the top 30 cm. Best estimate: ~65 t C/ha.

Total ecosystem carbon (AGB + roots + topsoil 0–30 cm)

Range: 810–1280 t C/ha

Best-guess total: ~1045 t C/ha

Notes and assumptions

These estimates assume: typical productive sites in the Strzelecki Ranges, no catastrophic disturbance (major wildfire or blowdown), and a fully developed old-growth structure. Dead wood, snags, and coarse woody debris contribute substantially to total aboveground carbon, which is why old-growth stands are so high in carbon density.

Carbon accumulation slows after ~150–200 years as mortality balances growth, so by 300 years the stand is very near its asymptotic carbon stock. Soil carbon is assumed roughly stable; small increases or decreases may occur but are minor relative to aboveground biomass.

Comparison to 50-year regenerating stands

50-year regenerating Mountain Ash: ~380 t C/ha

Old-growth 300-year stand: ~1045 t C/ha

So an old-growth forest stores nearly three times the carbon of a 50-year regenerating stand, mainly due to massive aboveground woody biomass.

The existing 50 year old Mountain ash forest stored approx. 370 T/Ha of carbon.

It was logged in 2024.

HVP's plan was to convert this to pines which stores 132 T/Ha…a loss of 238 T/ha

In a climate win for fellas the coupe will be revegged and will return to old growth…so in 200 years will potentially store 1045 T/Ha

Returning Fellas coupe to native forest has turned this from a significant reduction in stored carbon to the maximum for the site - a difference of 1283 T/Ha

If we take 10,000 hectares of 50-year-old regenerating Mountain Ash (Eucalyptus regnans) in the Strzelecki Ranges:

Let’s compare the two scenarios on a 10,000 ha landscape in the Strzelecki Ranges (~1100 mm rainfall, 300 m elevation).

Scenario 1 – Existing 50-year-old Mountain Ash

• Carbon per hectare: ~380 t C/ha

• Total for 10,000 ha: 3,800,000 t C

Scenario 2 – Replace with 25-year Pinus radiata rotations

• Carbon per hectare averaged over 100 years: ~132 t C/ha

• Total for 10,000 ha: 1,320,000 t C

• Difference vs. current 50-year Ash: 3,800,000 – 1,320,000 = 2,480,000 t C lost

Scenario 3 – Keep the 50-year Mountain Ash and allow it to grow to old-growth (~200 years)

• Carbon per hectare at ~250 years: ~1,045 t C/ha

• Total for 10,000 ha: 10,450,000 t C

• Gain vs. current 50-year Ash: 10,450,000 – 3,800,000 = 6,650,000 t C gained

Comparison summary (10,000 ha)

• Current 50-year Ash: 3.8 Mt C

• Replacing with pine rotations: 1.32 Mt C → net loss of ~2.48 Mt C

• Allowing Mountain Ash to mature: 10.45 Mt C → net gain of ~6.65 Mt C

CO₂-equivalent

• Net loss if converted to pines: 2,480,000 × 3.667 ≈ 9.1 Mt CO₂e

• Net gain if retained to old-growth: 6,650,000 × 3.667 ≈ 24.4 Mt CO₂e

Key points

• Replacing the 50-year Ash with short-rotation pine drastically reduces long-term carbon storage.

• Retaining and allowing Ash to reach old-growth maximizes carbon storage, more than doubling the current landscape carbon.

• The difference is driven primarily by the enormous biomass potential of old-growth Mountain Ash versus the much lower biomass of 25-year pine rotations.

The solid line shows a 50-year regenerating Mountain Ash continuing to old-growth (carbon rises from 380 t C/ha at 50 years to ~1,045 t C/ha at 300 years).

The dashed line shows the average carbon for 25-year Pinus radiata rotations (~132 t C/ha), which remains much lower over the same period.

The vertical dotted line marks the current 50-year Ash stand. This illustrates clearly the large carbon gain if the Mountain Ash is retained and allowed to mature versus converting to short-rotation pine.