Dun Mountain
The Dun Mountain and Nelson Mineral Belt form one of the most distinctive geological and ecological landscapes in Aotearoa. Located south‑east of Nelson City, Dun Mountain rises to 1,129m and is part of a rare belt of ultramafic rock that stretches from D’Urville Island in the north to the Red Hills in the south.
The Geology – How the Mineral Belt Formed
Around 280 million years ago, molten lava pushed into the ancient Gondwana crust, forming the ultramafic rocks seen today. As these rocks weathered, they created toxic, low‑fertility soils that are high in heavy metals and unsuitable for most plants and animals.
Only highly specialised species can survive in this harsh environment, which is characterised by high levels of iron, magnesium, cobalt, and nickel, challenging climate conditions, and unique ecosystems found nowhere else in New Zealand. Over millions of years, plants and animals have evolved to adapt to these conditions, creating a globally significant, fragile, and irreplaceable ecosystem.
Unique Biodiversity
Specialist Plants
The Mineral Belt supports around 28 native plant species, many of which are classified as rare, threatened, or nationally uncommon.
Look for:
- Mineral Belt Harebell (Wahlenbergia albomarginata ssp. olivina)
- Mineral Belt Pincushion (Colobanthuys “serpentine”)
- Mineral Belt Forget‑Me‑Not (Myosotis monroi)
These species have adapted to survive metal‑rich soils and extreme conditions.
Specialist Animals & Invertebrates
The most iconic species is the New Zealand’s Giant Land Snail (Powelliphanta hochstetteri consobrina), a carnivorous snail that relies on leaf litter and calcium from old shells.
Other species include:
- Forest ringlet butterfly (Dodonidia helmsii), now rare nationally
- Mecodema dunense, a localised ground beetle
- Alpine cicada (Maoricicada mangu gourlayi) named after Nelson scientist E.S. Gourlay
Birdlife & Lizards of the Surrounding Forests
The mineral belt merges into the native forests of the upper Maitai and Roding catchments, home to:
Lizards include the Nelson green gecko, forest gecko, and several skink species — though they are seldom seen.
This unique environment is under threat; if we lose it, it will be gone forever.
Threats to the Mineral Belt
Weeds
Invasive plant species threaten to alter soil conditions and out‑compete specialist native species.
Key threats include:
- Wilding conifers (especially Douglas fir)
- Gorse
- Spanish heath
Animal Pests
Browsers disrupt regeneration and alter the forest floor:
- Goats
- Deer
- Pigs
- Hares
- Possums
- Rats
People
Human activity can unintentionally spread weeds:
- Seeds carried on shoes, clothing, bikes, and backpacks
- Off‑track travel damaging fragile plant communities
- Collecting snail shells (illegal under the Wildlife Act 1953)
What We're doing?
Nelson City Council, through Nelson Nature, works to protect the unique ecosystems of the Mineral Belt by:
- Controlling wilding conifers, gorse, and Spanish heath
- Managing browsing animal pests (goats, deer, pigs) understory browsers
- Habitat restoration
- Supporting natural forest regeneration
- Monitoring plant and animal communities
- Working in partnership with and support from Nelson Tasman Forest & Bird and DOC
This work helps safeguard rare species.
What You Can Do
You can help protect this fragile and irreplaceable ecosystem
- Do not bring seeds into the area – clean shoes, tyres, packs, and gear
- Pull out small wilding pines you see
- Support restoration and pest control groups
- Take only photographs – leave the environment as you found it.
- Stay on marked tracks
- Record sightings on iNaturalist
- Leave snail shells where you find them – their calcium is essential for Powelliphanta survival
- Know that Powelliphanta snails and their shells are fully protected under the Wildlife Act 1953
Small choices help preserve this globally significant ecosystem.
Resources & Useful links
- Dun Mountain Ecology Brochure
- Wasp Wipeout - Wasp Control
- iNaturalist to identify plants and animals
- Dun Mountain Trail
- Forest and Bird
- Nelson Mountain Bike Club
