Fresh water wetlands

• Hamilton City

  Once had an extensive lake and wetland system. Remnants now include Lake Rotoroa (Hamilton Lake), Lake Rotokaeo (Forest Lake), and Horseshoe Lake. The Waikato River and its tributaries form an extensive gully system which contain small pockets of kahikatea and rare swamp maire forest.
• Hauraki district

  Includes the internationally significant Kopuatai Peat Dome and Firth of Thames wetlands. Also the Torehape Peat Mine, where the mined areas of peatland are being restored to a healthy wetland.
• Matamata-Piako District

  Matamata-Piako shares the Kopuatai Peat Dome with Hauraki District. This is New Zealand’s largest peat dome. It contains many threatened species and provides valuable habitat for native fish and birds. Entry to the dome requires a permit from the Department of Conservation, to protect this fragile ecosystem.
• Ōtorohanga District

  Contains the Waipapa Ecological Area where mountain mires were created after the Taupō eruption flattened the forest and deposited a layer of pumice. Sedges, tangle ferns, sundews and sphagnum moss grow on the peat, with swamp Coprosma and bog pine at the margins. The uncommon sedge Gahnia rigida grows here.
• Rotorua District

  Rotorua is famous for its lakes and geothermal features. Warm, swampy or steamy areas in geothermal fields may contain uncommon ferns like Cyclosorus that are normally found in the tropics.
• South Waikato District

  The Mamaku Plateau has high altitude wetlands among the native forest. These may contain sphagnum moss, rushes, manuka, flax and monoao (Dracophyllum). This district also shares many of the hydro lakes along the Waikato River with Taupō District.
• Taupō

  Home to New Zealand’s largest lake, Lake Taupō. It also has many wetlands at the lake edge, such as the extensive Tongariro River Delta and South Taupo swamp, and large flax wetlands at Waitahanui and Lake Rotoaira.
• Thames-Coromandel District

  The largest wetlands in this district are the estuaries, which are often backed by strips of freshwater wetland. For example, Duck Creek near Tairua Harbour, where fernbirds live in a diverse manuka-sedge wetland.
• Waikato District

  Contains a third of all the freshwater wetlands in the region. It is home to the extensive Whangamarino Wetland, several peat lakes and bogs and many riverine lakes created from the Waikato River’s meander across the Lower Waikato floodplain. It also includes the extensive Waikato River delta, where the river flows through a maze of swampy islands covered in kahikatea, flax, raupo, sedge and willow. Banded rail, bittern, fernbird and many other species live here.
• Waipā District

  Contains peat lakes formed at the end of the last ice age (over 15,000 years ago). The district council and National Wetland Trust are restoring Lake Rotopiko to create a National Wetland Centre. The Moanatuatua Scientific Reserve is one of the few sites in New Zealand where the rare giant cane rush (Sporadanthus) occurs.
• Waitomo District

  Famous for its caves and underground rivers. Has a system of freshwater dune lakes south of Kawhia Harbour which are fringed with raupō, flax and sedges. The lakes are home to dabchick, fernbird, crakes, bitterns, scaup and many species of native fish. There are also a number of kahikatea forests, particularly along the Mangapu River.

• Bogs - low nutrient wetlands

  Bogs are areas of low nutrient peat (partly decayed and waterlogged plant material) that are fed by rainwater alone and have high and relatively stable water levels. In these conditions, things decay very slowly. The dead plant material does not readily break down and builds up as peat, forming low domes, like the Kopuatai Peat Dome in the Hauraki Plains.

  The most common plants in Waikato bogs are jointed rushes, including the rare endemic giant cane rush (Sporadanthus) and the small wire rush (Empodisma).

  Other peat bog plants include:

  • sphagnum moss
  • orchids
  • sundews
  • bladderworts
  • sedges
  • umbrella ferns.

  Fernbirds, rare black mudfish, insects and the large orb-weaving spider live among the rushes in peat bogs. Many other types of bird and fish live on the more fertile edges of the bog. The rare cane rust month (Houdinia flexilissima) is found only in Waikato bogs, living inside the stems of the giant cane rush.
• Swamps and fens - fertile wetlands

  Fertile wetlands are fed by nutrient-rich ground and surface water, as well as rainwater. Their water levels vary seasonally and they are often flooded by water loaded with silt and nutrients when river or lake levels are high.

  Moderately fertile fens are found at the edges of low-nutrient peat bogs and peat lakes, and in depressions where there is some groundwater influence. Kahikatea, manuka and sedges may be found in these wetlands.

  Highly fertile swamps are greatly influenced by groundwater and surface run-off and may be found on the edges of lakes, in poorly drained river deltas and in wet gullies. Common plants include raupo, harakeke (flax) and some sedges. Swamps are very productive and support a wide variety of plants and animals adapted to seasonally changing water levels. They are readily invaded by introduced plants such as grey and crack willow, which can dominate the vegetation and degrade the wetland.

Types of swamp and fen vegetation

• Kahikatea forest

  Stands of kahikatea trees are a familiar sight around the Waikato lowlands. Native birds and other animals feed on kahikatea fruit and native bats may roost in them. Other trees that often grow alongside kahikatea include matai, kowhai, cabbage tree, and pukatea.

  Large stands of kahikatea swamp forest occur alongside the Awaroa Stream, which enters Lake Whangape, near Huntly.

  Find out more about kahikatea stands in the Waikato region.
• Mānuka

  This versatile tree grows in a wide range of habitats, not just swamps. Cabbage trees often dot the landscape in mānuka wetlands. Large populations of fernbird can be found among the dense mānuka.

  Mānuka wetlands are widely distributed across the region with major concentrations in the Waikato lowlands, including the Whangamarino wetland and the edge of the Kopouatai peat dome.
• Sedgeland

  Sedgelands occur in areas with still water, and are dominated by a wide range of sedges and rushes such as Carex, Juncus, Eleocharis, and Machaerina. Sedgeland is excellent fernbird and crake habitat, particularly where it grows alongside areas of manuka scrub or raupo.

  Sedgelands are widespread, but occur mainly in the large wetlands of the lower Waikato such as the Whangamarino wetland and the edges of Kopuatai peat dome.
• Raupō

  Raupō (bullrush) is a distinctive plant found in still, shallow water around lake edges and even ditches. Spotless crake and the threatened Australasian bittern often make their home in raupō.

  Large areas of raupō wetland are found in the Tongariro River delta at the southern side of Lake Taupō, and at the edge of the Lower Waikato lakes.
• Harakeke (flax)

  This hardy plant thrives in lowland swamps but can also cope in quite dry conditions. Cabbage trees are often scattered through harakeke wetlands and manuka may occur around the edges. Native fish, such as the giant kokopu, use flax and raupō at the edges of lakes and waterways.

  Flax dominated wetlands are most common in the Taupo area, particularly at higher altitudes (above 300 m). A large flax wetland occurs at Lake Rotoaira, with another at Waitahauni, adjacent to Lake Taupo.

• Drainage

  Drainage and cultivation have greatly improved our ability to farm land profitably in the Waikato region. But it has also caused the loss of 75 percent of our region’s wetlands. We must maintain our remaining wetlands to protect their biodiversity and maintain the services that wetlands provide (for example, flood management and improving water quality).

  Excessive drainage at the edge of peat bogs can cause a drop in the wetland’s water level. This can stop the formation of peat and changes the types of plants that grow there.

  It is not only drainage of wetlands or near wetlands that can affect their water levels. Changes further upstream, such as damming or channelling waterways, can change how much and when water reaches a wetland.

  Find out more about managing peat to protect surrounding wetlands.

  For policy information on diverting and damming water check out our Regional Plan.

   
• Hunting and harvesting

  Game bird hunting, eeling and whitebait harvesting are important traditions for many New Zealanders. Hunting and harvesting these species puts pressure on their populations, but it also encourages people to conserve wetland habitats. Conserving wetland habitats for hunting and harvesting has spin-offs for many other native animals and plants.

  Peat is harvested from some wetlands in the Waikato region (such as Torehape in the Hauraki Plains) for horticultural use. Drains are dug to lower the water level and dry out the top surface of the peat. The vegetation is removed and the dried out peat skimmed off the surface. At Torehape this is happening in sections, so that some natural vegetation is left to provide wildlife habitat. After the top layer of peat is removed, the water levels and native vegetation are restored to a functioning bog again.

   
• Grazing

  Stock with uncontrolled access to wetland areas can:

  • increase nutrient levels through their urine and dung
  • compact or erode the soil
  • disturb wildlife
  • graze on and trample wetland plants
  • open up sites for weed invasion
  • carry weed seeds in their hooves, coat, or dung
  • become bogged down and trapped.

  Wetlands, and valuable stock, can be effectively protected from each other with standard fencing.

  Find out more about grazing near wetlands and grazing in areas of native forest.

   
• Increasing nutrients

  Fertiliser applied to farmland can affect nearby wetlands through nutrient enriched run-off, leaching and spray drift. Nutrients can also enter wetlands during storms or floods, when eroded soil washes down into wetlands. While swamps play an important role in naturally filtering out sediments and nutrients, excess nutrients in wetlands, particularly low nutrient bogs, can change the delicate balance of plants and animals in the wetlands. At the margins of peat bogs, increased nutrients aid the invasion of exotic plants, such as grey willow.

  Research at Moanatuatua Reserve has found increased phosphorus levels in the peat bog, probably from top dressing (aerial application of fertiliser). Phosphorus has been show to inhibit the root growth of wire-rush, the main peat forming plant at Moanatuatua. Since 2002 the peat surface at Moanatuatua has shrunk by up to half a metre.

  Find out about the effect of nutrient enrichment in shallow lakes and the Waikato River.

   
• Plant and animal pests

  Deer, rabbits, hares, and pigs have become established in some wetlands and pose a threat to native plants and animals. Rats, cats, possums, hedgehogs and mustelids are also found in Waikato wetlands. They kill native birds especially during the breeding season when incubating birds are often reluctant to leave the nest. Young chicks and eggs are also taken, as are other native animals such as bats, lizards and insects.

  Exotic fish such as koi carp and rudd affect aquatic vegetation through grazing. They also affect water quality by stirring up sediments as they feed.

  Plant pests also threaten native biodiversity in many Waikato wetlands. They can grow very quickly and compete against native plants for space, nutrients and light. Grey willow, introduced in 1925, now covers over 10,000 ha of wetland in the region (one third of all the remaining area). 

  The exotic grass Glyceria maxima is a persistent problem for replanting programmes in some wetlands and requires ongoing management to stop it from smothering the young native plants. Other plant pests include various species of waterlily, parrot's feather and yellow flag iris.

  Our Regional Pest Management Strategy sets out management programmes for plant and animal pests in our region that need to be managed in order to protect our environment.

  Find out more about pests in the Waikato region.

   
• Fires

  Fires were a natural occurrence in wetlands, particularly large peat bogs. Many native wetland plants are adapted to fire. Some have underground rhizomes (runners) that can rapidly resprout after a fire. Others rely on fire for their existence as they grow in burn holes (small clearings created when fire removes the vegetation in localised areas).

  But wetlands now are much smaller than they used to be, and a single uncontrolled fire can burn most or all of a wetland. When a whole wetland is burnt, few plants and animals survive to recolonise the burnt area. Animal survivors in particular will not live for long without the cover and food provided by nearby vegetation.

  The lack of fires (because of necessary fire control) means that burn hole habitats are uncommon. This has caused some plants that depend on burn holes, such as the swamp helmet orchid Corybas carsei, to become threatened with extinction.

  In the 1980s two fires in the Whangamarino Wetland destroyed 57 per cent of the vegetation. These fires left large areas vulnerable to introduced plants. In areas of high fertility these exotic plants could dominate the native plants and prevent natural regeneration.