Sand dunes

Why protect our sand dunes?

Protect the dunes and they'll protect us

 

Spirits Bay.

 

Beaches and sand dunes are the narrow but precious bands of sand that lie between the land and the sea.

 

Sand dunes are natural habitats for many native species and, in their natural state, they protect land and property from erosion, storms, cyclones and tsunamis.

 

But many of our dunes are under threat, which creates instability, increased erosion and loss of native plant and animal life.

 

Large areas of Northland's coastal dunes have been modified for residential development and farmland. This has led to changes in dune stability, often resulting in vegetation loss and wind erosion.

 

Our dunes are also under pressure as the population grows. Wheels, feet and animals destroy dune vegetation. Even small losses in dune vegetation can lead to significant wind erosion.

 

The good news is that we can all play a part in caring for and protecting Northland's valuable dunes.

 

Vehicle on Rukaka Beach.Driving or riding on dunes destroys plants and causes erosion.

How do sand dunes work?

Sand dunes are always changing as they erode and build-up in cycles. Vegetation plays a critical role in the natural cycles of dune erosion and recovery that occurs on beaches.

 

Settled weather

Sand builds up on the beach and dunes.

 

Settled weather, dune diagram. 

During a storm

Waves erode the beach and dune, leaving a steep dune face. A bar is created as eroded sand settles offshore in the surf zone.

 

During a storm, dune diagram. 

After the storm

Sand is transported back onshore and rebuilds the beach. Dune vegetation grows seaward down the eroded dune face.

 

After the storm, dune diagram. 

Dune recovery

Sand blown landward from the beach is trapped by dune vegetation, gradually repairing and rebuilding the dune.

 

Dune recovery, dune diagram. 

Thanks to the Dune Restoration Trust of New Zealand for allowing us to reproduce some of its information. www.dunestrust.org.nz 

 

Native plant species in our dunes

 

View a larger version of Native Plant Species in our Dunes in pdf format (PDF, 850KB)

 

Native plant species in our dunes, diagram. 

Native dune plants...

… can

  • Reduce wind erosion.
  • Build up sand dunes which reduce wave erosion.
  • Speed recovery of dunes after storms.
  • Grow in the hostile coastal environment.

  

… can't

  • Prevent direct wave erosion.
  • Withstand excessive damage from people, stock or vehicles.
  • Cope with mowing.
  • Tolerate introduction of unsuitable exotic plants.

Pest plants in our dunes

In many coastal areas, introduced species have been planted to stabilise or beautify dunes.

 

Unfortunately these species aren't as effective at dune protection as native plants, and they can sometimes make erosion worse.

 

Many introduced species have also become a problem as they can over-run large areas and threaten native species.

 

Some of the problem species are agapanthus, exotic iceplant, purple groundsel, prickly pear, daisies, acacia, boneseed, coastal banksia, freesias, kikuyu grass and acacia.

 

Purple groundsel plant.Purple groundsel. Exotic ice plant.Exotic ice plant.

 

 

 

  

  

  

  

  

Help stop the spread of pest plants

Many pest plants are garden escapees – you can help by:

  • Composting garden waste instead of dumping it onto the dunes
  • Removing invasive introduced plants and replacing them with natives.

 

Contact the Northland Regional Council for removal techniques and suitable replacement plants.

 

Find our guidelines for weed control on sand dunes

Dune restoration

Dunes can be replanted to encourage natural processes, if there's enough space between the beach and buildings or roads.

 

Replanting can also re-establish important native plants that have become critically rare in some areas – like spinifex and pingao – and restore the natural character and values of an area.

 

Keep in mind that some areas are naturally unstable and are valued environments just as they are. Before you commit to a project that's trying to address dune stability, take a stroll along the beach and think about the natural coastal processes that are at work.

 

Northland CoastCare groups carry out dune restoration projects to protect and enhance native vegetation and replant it where necessary.

Dune care code

Dunes are adapted to natural coastal processes, but are fragile and easily damaged by human activities. We can all help protect our dunes and the plants and animals that live there by following the Dune Care Code.

 

Keep off the dunes

Wheels, feet and hooves kill the plants which protect the dunes.

 

Wheels destroy the dunes and dune plants and can disturb or kill native birds and wildlife

All vehicles – including 4WD, motorbikes and quad bikes – should follow marked tracks and keep to the hard sand.

 

Give plants a chance

Native sand-binding plants protect the dunes and help them recover after they have been eroded by storms. You can help protect the plants by keeping to the paths, following directions on signs and keeping out of fenced areas.

 

Keep stock in the paddock

Farm stock can trample sand dunes, birds and wildlife, and eat dune plants. Fence off coastal margins and keep stock off dunes.

 

Ride the waves, not the dunes!

Sandboarding on the dunes destroys plants and loosens the sand, causing wind erosion.

 

Horsing about is definitely out!

Riding horses through dunes can damage plants and wildlife. Use designated accessways to reach the beach and ride your horses on hard sand.

 

Leave our beaches litter free

Rubbish looks ugly and can be harmful to people and wildlife. Please take your rubbish home with you.

 

Don't let our beaches go to the dogs!

Ask your local district council which beaches you can exercise your dog on.

 

Always keep your dog under control and pick up its waste.

 

Get rid of pests and weeds

Rabbits and possums eat dune plants and shrubs, while garden plants and weeds smother native vegetation. Trap animal pests whenever possible and compost your garden waste rather than throwing it onto the dunes.

 

Leave sand and pebbles for future generations

It is illegal to remove sand, pebbles or rocks from our beaches. These materials are the building blocks of our coastline and take thousands of years to build up.

Take action – get involved

Contact the CoastCare Co-ordinator at the Northland Regional Council to find a CoastCare group near you:

 

Phone 0800 002 004 or
email mailroom@nrc.govt.nz

 

Fenced boardwalk over planted dunes. Establishing accessways, fencing off dunes and replanting with natives has been successful in restoring the dunes at Matapouri beach.

 

Caring for Northland's dunes brochure

Our Caring for Northland's dunes brochure can be viewed online or is available to download in pdf format.

 

Find the dunes brochure in our Resource Library