Coastal Planting

A coastal planting programme aimed at halting shore erosion on Rotoroa Island's northern beaches is already showing positive results.

Spinifex, flax and coprosma have all been planted along the dunes of Ladies' and Men's Bays in a bid to recover some of the up to five metres of sand eroded by intense easterly storms in recent years. Just how dynamic our coastal environments are was demonstrated recently with the effects of Cyclone Pam, whose power deposited close to five metres of sand back onto our eastern beaches again.

Rotoroa's ecologist Jo Ritchie, says the planting initiative came about after a visit by coastal bioengineer, Greg Jenks. "Greg has years of practical experience restoring coastal environments with bioengineering - using native plants to help stabilise the dune or beach fronts and gradually moving these out to trap sand.

"Greg's work at Mt Maunganui and Papamoa Beach on the east coast of the North Island demonstrates that using native plants, controlling weeds and managing how people get onto beaches are cost effective and sustainable solutions to beach erosion."

Jo says that in the past, Rotoroa Island's coast would have been dominated and protected with natural coastal vegetation, making the island better able to withstand natural erosion patterns. "What we are trying to do now is natural engineering with plants instead of bulldozers and rocks and sand."

Not only are the new plants helping shore up the island's beaches, they're also restoring natural coastal habitats for shore skinks and other native insect species. So far we can report enthusiastic growth of the new dune plants. Many of the spinifex have runners (long stems with multiple roots) that are at least four to five metres long, while the ice plants have trebled in size and are flowering.

More plants have since been introduced with the programme extended to Home and Maimai Bays. Pingao (the partner sand-binding grass to spinifex) will also be planted; pingao has stunning golden blades and chocolate brown seed heads.

"Everything is connected to everything else," says Jo. "More native plants equals more sand, more stable beaches, more diverse habitats for native plants and animals, and immensely enjoyable places for people."