Te Matapuna Wetland

Project Tongariro and Department of Conservation are busy restoring the Waimarino Recreation Reserve by removing willow trees in this part of the South Taupo wetlands. Waimarino is a rich mix of dry land, wetland and open water lagoon, with native plants and birds important to wildlife conservation, all of which will benefit from removing grey and crack willow currently choking the reserve.

Much work has already gone ahead through aerial spraying and ground control of the willows over the last two years and this will continue this summer. We will be monitoring the bird life and how it responds to the work.

If you notice us scrambling around with our kayaks and feel a bit curious then please come over and chat with us, or maybe accompany us into the reserve and join in?

Project Tongariro is an incorporated society supported by a dedicated volunteer force, with important projects across the Tongariro National Park and area. If you would like to learn more then please contact us on 07 386 6499 or email info@tongariro.org.nz


WAIMARINO WETLAND RESERVE AND MAORI TRUST LAND - AERIAL VIEW

Saving a swamp may not sound a very exciting or glamorous project to take on but that is exactly what Project Tongariro is working on in conjunction with the Department of Conservation in Turangi. The Waimarino Wetland near Motuoapa, where efforts are being concentrated, is part of the much greater South Taupo Wetland that extends around the southern edge of Lake Taupo between Motuoapa and Waihi.

From SH 1 near Motuoapa there are few visual clues of the large body of water lying between the road and the base of the bush-covered headland jutting out into the lake and protecting Motuoapa Bay. A short climb, however, along the track behind the Motuoapa Motels to a lookout over the bay reveals a different picture. The triangle of water and swampland contained between SH 1 and the headland is spread below, contained by the narrow strip of beach and scrub connecting the headland to the mouth of the Waimarino River and the band of bright green crack willows edging Motuoapa Bay. Thin parallel strips of vegetation running through the wetland mark where the Waimarino River once ran when in earlier times it entered Motuoapa Bay. Artificial raising of the level of Lake Taupo to feed hydro electric power stations along the Waikato River has increased the original size of the wetland, which in the past was an important source of food to Maori living in several villages that once stood along the lakeshore near Motuoapa. Cliffs behind the villages and on the headland were used as burial sites.

The word swamp doesn’t usually conjure up beautiful mental images – just visions of mucky mud and weeds - but the Waimarino Wetland is a surprisingly serene and beautiful place. It provides very important habit for a number of threatened species of birds, two rare species of native buttercup and a native snail found only on the headland and on Motutaiko Island in Lake Taupo. Birds commonly seen on the water are cormorants, scaup or black teal, black swans, mallard and paradise ducks, and white-faced herons, while grey warblers, silver-eyes, chaffinches are common in scrub areas and bell birds and tuis occupy the extremely tall kanuka forest on the headland. Less frequently seen are the secretive spotless and marsh crakes and bitterns although booming by the latter indicates their presence. Fern birds frequent patches of manuka and although hard to see are located by the double ‘tick’ sound of a pair of birds.

 

So why does this wetland, or swamp need saving?

It seems healthy enough. Most of the Waimarino Wetland is owned by local iwi but a portion of it, which extends onto the lower end of the headland, is conservation estate. The department is concerned about the spread of Grey Willow (often called Pussy willow), which has gradually infested the entire South Taupo Wetland. Grey Willow spreads easily by producing vast quantities of seeds that are carried by the wind.

 It had started appearing in Lake Rotoaira to the south of Lake Taupo and the fear was that it would soon be found in Tongariro National Park and the Kaimanawa ranges. If left to grow unchecked in the Waimarino Wetland it will eventually choke it to death. Environment Waikato shares DoC’s concerns as they are tasked with looking after the health of Lake Taupo. A decision was made to start with trials on the Waimarino section. And this is where the Tongariro Natural history Society comes in.

With its pool of volunteer workers already doing conservation work in the Tongariro Taupo Conservancy it was the ideal organization to carry out the work to find out just what was in the wetland and to carry out trials to work out the most effective way of eradicating the willows. Scientific expertise is supplied by DoC and funding for the work has come from the Waikato Ecological and Environmental Conservation Trust. Walking around in the mud in thigh waders to do this work is hard going, and often entails pushing through flax and scrub laced with blackberry. There are also the dangers of stepping into holes or the very deep mud in the old stream beds, which can be difficult to get out of without assistance!

Areas of willows have been treated with herbicide, either by cutting and pasting the stumps, drilling holes into the trunks, or by boom spraying by helicopter. The herbicide used is one that did not target monocotyledons such as cabbage trees, sedges, toe toe and raupo and only patches that were almost entirely grey willow were sprayed. Follow-up checks on the areas controlled show how successful and cost effective the spraying was compared to the other methods. Under dead willows that had been sprayed were healthy sedges and other cotyledons. Patches of an introduced water weed that also has the potential to choke the wetland were also killed by the spray. The other more labour intensive methods will still have to be used, however, on willows that stand within or along the edges of native vegetation.

Local iwi have watched the work being done in the wetland with great interest and some are now keen to clean up the areas of willow on their land. They see the potential of the Waimarino Wetland as a place for bird watching, possibly from boardwalks or hides.