Mountain ash (Eucalyptus regnans)

Eucalyptus regnans, known as mountain ash, is one of the most remarkable trees on the planet. It grows up to 100 meters tall, making it the tallest flowering plant and the second-tallest tree in the world. It forms majestic, almost “cathedral-like” forests in southeastern Australia, among the fastest-growing and most productive ecosystems on Earth.

However, today this species faces a serious threat: its forests are disappearing rapidly.

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Status

Endangered (EN)
The population is shrinking sharply, especially after large-scale wildfires.

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Why is it disappearing?

Megafires
Eucalyptus regnans is not well adapted to extreme fires. If the interval between fires drops below 20–30 years, the population cannot regenerate in time.

Logging
One of Australia’s most valuable timber species. Intensive harvesting of old-growth stands has drastically reduced its natural range.

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Importance for the ecosystem

• the tallest flowering plant in the world – a symbol of the Australian wilderness

• creates unique rainforest structures that host hundreds of species

• supports endangered animals (e.g., Leadbeater’s possum)

• old trees store large amounts of carbon and are key to climate stability

Forests of E. regnans rank among the most ecologically valuable on Earth.

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Appearance

• Height: 70–100 m (sometimes more)

• Trunk: straight, grey, with smooth to fibrous bark

• Crown: tall, light green, allowing sunlight to pass through

• Leaves: lanceolate, aromatic, typical of eucalypts

• Growth: very fast – one of the fastest-growing tree species on the planet

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Where and how to plant

Mountain ash requires a climate similar to its native range in Australia.

✔ Ideal regions

• Tasmania

• Victoria

• cooler tropical and subtropical areas with high humidity

• sites with higher elevation and regular rainfall

✔ How to plant

• in deep, moist, well-drained soils

• requires full sun

• protect young trees from frost and fire

• suitable only for large restoration or experimental plantings

• not suitable for cities or dry regions

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When to plant

Ideally in spring or at the beginning of the rainy season (in the subtropics).

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Why plant it

• to support the conservation of one of the world’s most iconic trees

• to restore forests destroyed by megafires

• strong contribution to climate stability thanks to high carbon accumulation

• part of global efforts to protect the tallest and fastest-growing trees