An aerial view of the damage caused to the ecologically significant Kaimaumau wetlands after it was devastated by fire this past week.
An aerial view of the damage caused to the ecologically significant Kaimaumau wetlands after it was devastated by fire this past week.
Full recovery of the Kaimaumau wetland following last week's massive fire could take more than a decade — and that's only if invasive weeds are kept out and no more draining is carried out in the area.
The fire, which started on Saturday and was largely contained byWednesday, swept through more than 2000ha of the roughly 3000ha Kaimaumau-Motutangi wetland complex.
Department of Conservation Kaitaia operations manager Meirene Hardy-Birch said it was one of New Zealand's most ecologically significant wetlands.
With less than 10 per cent of the country's original wetlands remaining, its conservation was of national significance.
It was likely the fire had led to a decline of several threatened species and the habitat they relied on, such as a nationally critical sun orchid called Thelymitra ahipara which was found at only one other location in New Zealand.
Typical wetland vegetation at Kaimaumau before the fire. Photo / DoC
It was also a key site for the threatened-nationally critical Australasian bittern or matuku and the at risk-declining black mudfish.
Without knowing exactly where the fire had been, how fast it had travelled or how deep it had penetrated, however, it was not yet possible to assess the effects on any threatened species or the overall ecosystem.
Spiranthes australis or ladies tresses orchid is one of the at-risk plants found in the Kaimaumau-Motutangi wetland. Photo / DoC
In the short term some species could benefit because fire created open spaces, which favoured threatened plants such as orchids because they were relatively short and demanded plenty of light.
For example, an area at Lake Ohia affected by fire about 10 years ago now supported the largest population of threatened bog clubmoss in Northland.
''But the benefit of fires to threatened plants will come at the expense of other wetland species, such as mudfish and bittern,'' Hardy-Birch said.
Some vegetation would not recover but other plant species would re-establish from seed or underground roots and shoots, as long as the fire hadn't penetrated the peat or travelled slowly and cooked everything in it.
The Australasian bittern or matuku is nationally critical, the same conservation status as the kākāpō. Photo / Terry Oliver-Ward
While fire was a natural process in 'gumland' wetlands of the Far North — occurring naturally before humans arrived due to lightning igniting the flammable peat soils — the increased frequency of fire was a major threat.
''A full recovery of the wetland vegetation may take some time. Research indicates it can take 10-15 years for wetland vegetation to recover to the pre-burn state. This highlights the risk that repeated and frequent burning may have,'' she said.
It was critical weeds were not allowed to dominate as vegetation returned.
Kaimaumau was already under threat from Sydney golden wattle and other fire-adapted Australian weeds that could quickly take over, leaving no place for indigenous species.
Hardy-Birch said weed control would be crucial in healing Kaimaumau, as was maintaining a high water table unaffected by drainage.
Forest & Bird Northland conservation manager Dean Baigent-Mercer earlier told the Advocate the Kaimaumau wetland had been ''under attack'' in recent decades from drains dug around its edges, illegal swamp kauri mining, illegal wetland conversion, peat mining applications and applications for water extraction for avocado growing — as well as recurring fires.
''It's past time we gave Kaimaumau a break, blocked up the drains and give appropriate respect and protection,'' he said.
