Northland landowners can help with efforts to combat climate change by protecting and enhancing wetlands, according to Northland Regional Council biodiversity manager Lisa Forester.
Wetlands are important because they are the sponge and flood barrier that help keep waterways healthy, as well as being a major natural carbon store.
She said, historically, more than a fifth of the region was covered in wetlands. About 5 per cent remains, which is roughly half the national average.
A research update this month from New Zealand and international researchers has found a loss of more than 90 per cent of what would have been existing originally on New Zealand land.
The total area of wetlands in New Zealand is now reported as 249,214ha, just 10.08 per cent of the historical extent, according to the New Zealand Journal of Ecology.
The research was conducted by researchers at Manaaki Whenua - Landcare Research, University of Tehran, Iran, and Leibniz Institute for Agricultural Engineering and Bioeconomy, Germany.
The study, which was funded by the Ministry of Business, Innovation and Employment, showed that wetlands continue to be lost, with 5454ha developed between 1996 and 2018.
Forester said the carbon storage role of wetlands was worth more consideration in terms of climate change.
"Peat in wetlands acts as natural storage for carbon. However, if a wetland is drained the reverse happens as the peat dries out. Then it becomes a source of CO2, which contributes to greenhouse gases,'' she said.
"Research in the US has found that if 20 per cent of a catchment is in wetlands, flood peaks will be reduced by 60 to 80 per cent. In the winter they fill up and over summer the water is released slowly feeding streams and keeping water flowing.
"Wetlands are amazing wild places, providing a home for a huge range of animals and insects, lizards, plants and fish,'' she said. "Many are threatened species that are unique to New Zealand.''
Forester emphasised that the NRC's work was "not about rushing around trying to protect every wet patch".
As well as the typical raupō swamp, Northland has some unusual types of wetlands that are not always easy to identify. These include gumlands, seepages and ephemeral wetlands.
The regional council's land management advisors and biodiversity team members work closely with communities and landowners to assess the types of wetlands on their land and how they can be protected and enhanced, including providing support with funding applications to the NRC Environment Fund. Funding can be allocated to individuals and voluntary groups for eligible projects.
Further to this, the Ministry for the Environment (MfE) has recently published information to support councils and help landowners identify wetlands, taking into account the vegetation type, soils and hydrology.
As well as providing funding, the NRC has resources available such as the recently revised 'Looking after your wetlands' guide, aimed at providing landowners with practical advice around a number of issues such as weed and pest control and restoration planting advice.
Weeds are one of the greatest threats to wetlands. The first step is a weed audit, identifying which weed species already exist and how widespread they are. The NRC's online 'Pest Control Hub'
helps with the identification of weeds and how best to control them.
If using herbicides, it's important to always follow the manufacturer's instructions and make sure they are registered for use near water. Maintaining or restoring natural water levels in a wetland is one of the main ways that landowners can help wetlands improve and achieve a natural balance. Many wetlands become degraded or weedy because their water levels have been lowered by nearby drainage.
As well as having funding to support the fencing of wetlands and waterways, the council also has funding to support fencing and planting of erosion-prone land and the stabilisation of hill country farmland through the supply of poplars and willows. The aim is to reduce the amount of sediment coming off some of Northland's more marginal hill country and entering waterways, estuaries and harbours.
A monitoring programme of wetlands that have been fenced with the help of the Environment Fund has shown the benefits of the protection work.
"We want to be aspirational. We are down to 5 per cent. Can we grow wetlands to 7 or 8 or 10 per cent? The only way is to take opportunities and work with landowners to turn land not needed for farming back into wetlands,'' Forester said.