18 May 2023:
Fulton Hogan has transformed the two hectare LINZ gravel extraction site on the banks of the Motueka River into a wetland.
The experience at the site – where 25,000 tonnes of gravel was extracted over the last 18 months – will be valuable for the larger (21 ha) Challies site adjacent to the Waimea River 50 km south.
Fulton Hogan is converting Challies into a wetland – in conjunction with the Tasman District Council and local iwi – in five stages between 2024 and 2036, when the wetland will become part of the Waimea River Park.
Fulton Hogan’s Nelson Environmental Manager Bruno Brosnan says the Motueka experience is a chance to learn more about how best to create pockets of biodiversity.
“Over the past 170 years more than 99 percent of Nelson/Tasman wetland has been lost to agriculture and horticulture, which makes efforts to begin a process of redress all the more important,” Bruno says.
Fulton Hogan contracted FuturEcology Ltd to plant five species of rush in the water at the LINZ site – the large rush Eleocharis sphacelata (kuta), Machaerina articulata (Baumea), Schoenoplectus tabernaemontani (Kāpungawhā), Cyperus ustulatus (upoko tangata) and Juncus pallidus (tall swamp rush).
In combination with Dacrydium dacrydiodies (Kahikatea), these plants will provide a resource for other like projects in the region. They were once common throughout the region but are now extremely rare. Riparian species such as Carex secta (pukio) and Phormiun tenax (harakeke) provide a strong buffer around the water’s edge.
FuturEcology managing director Robert Fryer says it has been an exciting opportunity to create a functioning wetland in an area previously lacking natural biodiversity.
“The key has been creating a true wetland with shallow littoral margins for rushes, as these are the most productive zones in any wetland or riparian planting. The combination of engineering, construction and ecological skills is something we are very proud of.”