Work to restore islands in the Waikato River is a step closer with the completion of an illustrated species guide to plants already established on the islands.
The photographic guide is the first step in a joint NIWA, Waikato-Tainui project to restore the Maurea Islands in the stretch of the Waikato River upstream of the Rangiriri Bridge, south of the Rangiriri pa site.
The project, funded by the Waikato River Authority, will see the islands replanted with culturally significant and ecologically appropriate native plants that are disappearing on the river.
NIWA wetland ecologist Kerry Bodmin said information from plant surveys conducted on the islands had found they were overrun with highly invasive pest plants, in particular yellow flag iris, alder and reed sweet grass.
"We also identified a few remnant native plants that will provide a source of seedlings for the restoration project."
NIWA and the Waikato Raupatu River Trust (WRRT), in conjunction with Landcare Research and the Department of Conservation have been working closely with whaanau from Maurea Marae to find out what plants and animal life local iwi regard as culturally important for the islands. That information will be included in the restoration plan to be completed by the end of September.
WRRT Policy Advisor (Strategy) Cheri van Schravendijk-Goodman said there had been significant changes in that stretch of the river over the past 25 years and identifying the plants that currently existed was an important step in understanding how to eradicate and manage them.
"There is very little available at a practical level to help people with River Island restoration."
The illustrated species guide will go some way towards filling that gap and enable people to increase their knowledge and understanding to create the right habitat to fully restore native vegetation on the islands.
"This is really a broad, holistic project, it's not just about the plants, it is also about traditional and contemporary knowledge transfer to restore and protect the health and well being of the whole Waikato River," Cheri van Schravendijk-Goodman said.
The plan for the western island, which is just over a hectare, is to use native plants to outcompete the pest plants. Harakeke will replace yellow flag iris, kahikatea will replace alder and purua grass will take on the reed sweet grass.
On the eastern island, which is slightly smaller, herbicide is being used to control the weeds followed by replanting.
The different approaches to pest plant management will be compared to see how each performs.
Meanwhile, work on the eastern island has already been undertaken with Waikato Regional Council spraying yellow flag iris to stop the downstream spread of yellow flag iris seeds.
The project also received assistance from the Waikato Catchment Ecological Enhancement Trust, and staff from the Waikato Area Office at the Department of Conservation.
