Wetlands and lakes
A wetland is in general terms any land that is permanently or frequently wet and supports a natural ecosystem of plants and animals adapted to wetland living. Wetlands include streams, swamps, bogs, lakes, lagoons, estuaries, mudflats and flood plains.
Our district has very few wetlands and only a few minor lakes. Historically around 90% were drained when the land was converted to pasture. Those that remain make up small farm ponds and dams, however together these are significant habitats for water birds, fish, eels and insects.
Many farmers, recognising the conservation value of wetlands, are now fencing and restoring these areas on their land. There are an estimated 600ha of wetlands in the district. Most of these are on private land.
Healthy wetlands with dense vegetation serve important ecological functions in the landscape. Not only do they provide critical pockets of habitat for native and game species, they also benefit surrounding farmland.
The damp soils and dense native vegetation can:
- break down nitrogen from surface runoff and leaching (denitrification),
- filter and break down effluent particles,
- trap sediments in overland flow,
- trap harmful micro-organisms such as bacteria which are either retained by the soil, or killed by exposure to sunlight, and
- protect the surrounding land from flood damage through absorbing and slowly releasing water.
Wetlands are also sources of mahingakai (eels), rongoa and traditional materials such as flax. Coastal wetlands such as estuaries are highly productive nurseries for fish. Many wetland areas are also used recreationally.