Thousands of sand dune plant seedheads are gathered from Northland beaches in summer, and propagated so locals can return the plants to their coastline.
About 250,000 nursery-raised sand dune plants are improving the health of Te Tai Tokerau beaches thanks to Northland coastal communities’ efforts over the past 20 years.
The native spinifex and pingao dune plants have been grown from seeds gathered by hundreds of people over that time — and planted at various surf beaches from Cape Reinga to Mangawhai along the east coast, and to Ripirō Beach along the west coast.
Northland Regional Council senior biodiversity advisor coastal Laura Shaft said the communities’ efforts were vital.
Northlanders from 30 CoastCare groups, hapū and schools are among those who have played a role in a cycle of seed gathering to produce the pingao and spinifex dune plants.
Laura Shaft checks out spinifex at Ocean Beach
Pingao seeds are harvested before Christmas. Seeds from tumbleweed-like female sand dune spinifex seedheads are gathered through January and February.
This year’s annual summer seed gathering is currently taking place around Northland.
The sand-binding native grasses’ seedheads are gathered in brown paper rubbish bags, then taken to Northland Regional Council for a specialised nursery in Whakatāne, or directly to several nurseries, including at Ngātaki, Ngunguru and Mangawhai.
The resulting young plants are planted in their source dunes about 18 months later.
“They’re quite tricky to grow, not like normal nursery plants.”
Dune health is the focus for NRC trio (from left) Laura Shaft senior biodiversity advisor-coastal, Charley Cairns coastal science intern and Maria Secker biodiversity advisor CoastCare.
Photo / Susan Botting
The iconic golden rolling female spinifex seedheads on Northland surf beaches signal spinifex seedhead gathering time.
Gatherers head for areas of dunes thick with male and female seedheads, harvesting the latter.
Each seedhead contains about 100 spikelets. These contain fertilised seeds and are anchored into the seedhead’s centre by their heads.
“We collect seed from a specific beach. It’s tracked from that stage through its nursery growing then planted out back at that beach or very close by,” Shaft said.
Native New Zealand dune plants play a special role in making sure Northland beaches survive for summer fun
The dune grasses grow to about knee height, their leaves slowing passing winds at about the height where most of the sand they carry is found. This results in the sand falling to the ground around the plant.
More sand builds gradually. Native dune plants thrive in constant movement.
Some of that sand at the dune’s seaward edge can be washed out to sea when storm waves smash into the dunes — only to return through a different sort of wave action when waters calm.
Dunes are sand reservoirs, replenishing the beach.
Shaft said Northland’s sand dune strips were facing an intensifying coastal squeeze. They’re in a zone that’s constantly under pressure from both sides, with urbanisation and development from the land behind, and the pressures of climate change sea level rise in front.
Sand dune plants are easily damaged by people, horses and vehicles.
Weeds are an ongoing issue, with problems from garden plants and grasses such as iceplant, Kikuyu and buffalo grass.
The width of a beach’s dune strip was important, Shaft said.
Too narrow and it would constantly be at risk of disappearing in a storm.
Spikelets carry fertilised seeds at their tip. Seedheads with spikelets are collected by locals to be grown into plants that go back into sand dune 18 months later Photo / Susan Botting
Sand dune systems ideally graduated from foredune at their front beach edge to mid-dune then back dune at their rear. Many Northland dune systems no longer have complete graduation.
Dunes play an important role in protecting the land behind them and can be home to native lizards and other creatures.
Shaft said Northland dunes faced growing pressures and were only just holding their own in some areas.
Dunes in areas such as Langs Beach and Long Beach were thriving as a result of communities’ seed gathering and planting and general dune care.
But others such as at Taipa, which had ongoing weed issues, were not faring so well.
Shaft said all Northlanders could play their part in looking after dunes.
This could be something as simple as making sure to use beach access boardwalks rather than crossing the dunes, or not riding motorbikes or four-wheel drives over dunes.
Killing off dune plants could accentuate sand dunes blowing in onto the land.
