Southern wetlands are fragile, important to the environment, and under increasing threat writes AMY MILNE.
Wetlands are the earth's kidneys.
They are filters that purify and store massive amounts of water. It's wetlands that maintain the health and balance of surrounding areas by supplying a food source to thousands of plants and wildlife.
Southlanders have world-class wetlands on their doorstep but they're under threat and it's getting worse.
In the past three years two fires have destroyed almost 2000ha of the Awarua-Waituna Wetlands. The bigger of the two was at Seaward Moss wetland, near the Tiwai Point aluminium smelter, sweeping across about 1300ha. The second was further northeast at Waimahaka.
Both were the result of burn-offs on nearby private land that went wrong.
These are the source of huge frustration for Conservation Department (DOC) Awarua-Waituna Wetlands project manager Sally Chesterfield and Awarua-Waituna community relations ranger Polly Bulling.
The quick and rapid destruction these fires have caused in these areas will take years to repair. They are never expected to return to their original states.
"Unfortunately we don't have a super-sized dialysis machine to plug into," Ms Bulling says.
The most recent of the two fires ignited on December 29.
It started after spreading from a burnoff at Waimahaka on land belonging to Murray Maxwell.
The blaze destroyed 584ha of land, including about 280ha of land within DOC's Awarua-Waituna Wetland catchment, before it was officially put out on January 12.
Six helicopters (for the first two days), five fire crews and 12 support staff spent hundreds of hours fighting it, Ms Chesterfield says.
The area's thick peat soil, reaching up to 2m deep, and massive underground tree-root systems made it almost impossible to put out hotspots metres below the surface.
The total cost of fighting it stands at about $500,000.
Southern Rural Fire Authority principal rural fire officer Mike Grant says Mr Maxwell did not have a valid permit to light a fire on his property. He had obtained one at some stage but it was out of date and not specific to the fire he lit on December 29, Mr Grant says. He has since been billed the $500,000 cost of putting out the blaze.
It highlights the importance of people reading their fire permits to ensure they understood what they are allowed to do, he says.
Out of the 800 or more permits issued each year, only about 0.5 per cent resulted in an uncontrolled burn.
Despite the authority being confident its permit system is sound, Mr Grant says it is reviewing parts of it and has agreed to meet concerned stakeholders later this year to discuss any concerns.
Nevertheless, any fire can easily become a deadly one, especially in a wetland.
A big fire on conservation land can displace and kill hundreds, if not, thousands of individual native animals, insects and plant species, Ms Bulling says.
It also opens the land up to weed invasion and huge continuing financial costs associated with fighting it, Ms Chesterfield adds.
The 1300ha of wetlands destroyed at Seaward Moss reserve, near Tiwai, three years ago is one prime example.
While it's showing positive signs of regeneration, so is the invasive weed spanish heath as well as pests such as rabbits, hares and deer.
The weed had been a problem for a long time before the fire, but it was manageable. Since the fire it has become more aggressive in the area and is increasingly hard to fight.
"What was a little scab has become a giant one," Ms Chesterfield says.
Spanish heath is prolific; it grows fast and releases up to 9 million seeds every two years. The seeds can lie dormant in the ground for five years before sprouting. Fighting it was both expensive and invasive.
The weedkiller to destroy it literally "burns everything" in its path and, because of this, can't be applied by a broad-stroke technique, such as aerial application.
It has to be carefully applied manually to each individual spanish heath plant on the ground, making controlling it labour intensive and therefore very expensive, costing about $80,000 annually.
"The saddest part is it could all have been prevented," Ms Chesterfield says.
"Every time there's a fire our energies get diverted away from other conservation work to make sure these areas are coping okay."
- © Fairfax NZ News
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