Waikato’s Whangamarino Wetlands recovering from massive fire

Signs of recovery are growing from the ashes of Whangamarino Wetlands after a scrub fire burned through more than 1000ha of vegetation in October.

The fire was first reported to emergency services on October 21 and grew to about 19km in diameter before Fire and Emergency NZ declared it contained and under control.

By the time the fire was brought under control, it had burned through about 1039 hectares of wetland, releasing an estimated $9.6 million of carbon into the atmosphere.

Initial Department of Conservation (DoC) estimates that weekend suggested the habitat could take up to 30 years to recover.

Now, more than 14 weeks after the fire, the department’s assessment is more hopeful.

According to a DoC statement released today, the internationally significant habitat has shown more resilience thanks to the healthy state of the peatland before the blaze.

The October Whangamarino Wetlands fire burned through about 1039ha, releasing an estimated $9.6 million of carbon into the atmosphere. Photo / Malisha Kumar

DoC Whangamarino ranger Lizzie Sharp said thanks to relatively high water levels in the peatland before the fire, only a shallow layer of the peat soils was burned.

“The wetland is showing signs of hope,” Sharp said.

“The peatland areas of Whangamarino were healthy before the fire as it wasn’t being actively drained and had good vegetation cover dominated by native plants, so we’re more confident about its recovery.”

While Sharp said the local environment could still take decades to regain its lost biodiversity, efforts were under way to aid recovery.

“It’s like the peat bog has lost its skin. It is still vulnerable and losing water more easily than it should. The new conditions are inviting for weeds like willow, royal fern and pampas.”

She said the recovery plan would focus on controlling invasive weeds and would give the native peat vegetation time to recover from their seed sources that survived the fire.

“Peat bog wetlands are normally low-nutrient environments and the plants living there have adapted to those conditions. The firefighting effort used water from nearby waterways which had much higher nutrient levels, so we want to understand how the wetland responds to this.”

This image of Whangamarino Wetlands six weeks after the fire shows native sedges and wire rush recovering. Photo / Department of Conservation

DoC principal science adviser freshwater Hugh Robertson said other peatland fires in New Zealand had emitted more than 200 tonnes of carbon a hectare, but the loss of carbon at Whangamarino was likely to be only about 50-80 tonnes a hectare because the wet peat soils did not burn.

“Peatlands are great carbon stores because the vegetation in them which holds the carbon decomposes very slowly, trapping it. It’s like the vegetation freezes in time,” Robertson said.

“However, peat soils are highly flammable, particularly when they’re dried out. Re-wetting our wetlands will make them less susceptible to the impacts of fires which in turn will reduce greenhouse gas emissions.”

The good news comes before World Wetlands Day, celebrated annually on February 2.

The day highlights the influence and positive production wetlands have on the world and brings communities together for the benefit of wetlands. It also raises global awareness of the significant role wetlands play for the planet and people.

Charred mānuka trunks among growing native peat sedge species, six weeks after the fire. Photo / Department of Conservation

Maryana Garcia is a Hamilton-based reporter covering breaking news in Waikato. She previously wrote for the Rotorua Daily Post and Bay of Plenty Times.