Port Hills fires: Decades of conservation work up in flames (Video)
Decades of conservation work has gone up in smoke as the Port Hills fire rages across some of the region's last remnants of native forest.
While the fate of several important reserves remains hidden beneath smoke and beyond cordons, some reserve land has been confirmed destroyed.
The fire spread across the hills at a rapid pace, finding plenty of ammunition in the highly flammable gorse, broom and pine forests threaded across the hills.
There are 39 reserves on the hills, containing some of the few examples of native forest in Canterbury.
Among the largest is the Ohinetahi Bush Reserve, owned by the Summit Road Society, which has been severely damaged by the fire.
The 150-hectare reserve is protected by a QEII covenant and contains regenerating native forest home to a native bird population.
More than half of the reserve had been affected by the fire, society member Tony Edney said, including the destruction of a kanuka forest thought to be 80 years old.
"It's [been] decades of work. Decades of work.
"We're all just trying to come to terms with what's happened."
He watched the fire roar down the valley from his Governors Bay home, overcoming the wind.
I was under the impression the reserve may be relatively safe because it was a steep slope and fires tend to go up rather than down.
"Despite having the contour and the wind against it, the fire progressed quite rapidly downhill.
"We've got a large part of our central reserve that has been torched. There's not a lot left standing."
Thousands of hours of work had been lost, gone with the native forest at the reserve's centre.
"It was a fabulous habitat for bellbird and there were a lot of other natives starting to come up through the kanuka. It's been a real blow to us, losing that really important resource."
The fate of other reserves was not yet known, as those responsible stay away to allow firefighters to do their work.
There were fears for the recently re-opened Sign of the Kiwi, but it escaped the blaze, the Christchurch City Council said.
As of Friday night, the extent of the damage to other reserves nearby was still unknown, due to access difficulties.
Aerial imagery shows extensive vegetation loss around Kennedys Bush, one of New Zealand's oldest scenic reserves, but the bulk of it appears to have had a lucky escape.
The condition of nearby Sign of the Bellbird, however, remains unclear.
'THANK HEAVENS FOR SMALL MERCIES'
Further towards Tai Tapu, some good news. The Omahu Bush Reserve, one of the finest blocks of native bush on the hills, appears to have escaped unscathed.
The 150 hectare reserve, which is home to dense, regenerating native forest, joins with Gibraltar Rock.
Omahu Bush honorary ranger Paul Tebbutt said it appeared the bush was safe.
"From what I understand, there's been no damage there. I haven't been able to get there because the road's closed... but I'm pretty confident there's been no damage to that reserve," he said.
The reserve is owned by the Summit Road Society, which also owns the heavily damaged Ohinetahi Reserve.
"If we've lost Ohinetahi, than that's a huge blow. I suppose if we're still got [Omahu] then that will be something for us to go and have a cup of tea while we think about what we're going to do with Ohinetahi.
"Thank heavens for small mercies."
Any loss of native ecosystems would be devastating due to their rarity in Canterbury.
There had been enormous effort into returning native birds such as bellbirds and tomtits to the hills.
"There's very little dryland forests left either on the Canterbury Plains or the foothills, so loss of any of these is hugely significant," said Dr Colin Meurk, a Landcare Research ecologist.
"There's been a huge amount of smoke pouring out of those general areas, but it's been hard to tell just how much has gone into the heads of those gullies where a lot of that remnant forest is most surviving."
He said people may have lost a lifetime's worth of work to the fire.
Rangers and volunteers had been trying to return species such as bellbirds, tomtits and tui to the hills.
"The rangers have been working assiduously on not only restoring the vegetation but doing a massive amount in terms of predator control and building up wildlife numbers.
"I've just been thinking about all of that work that those dedicated people have been doing, both those employed by the council and DOC, but also hundreds of volunteers over many years.
"It really is horrifying."
The Port Hills were vulnerable to quick-moving fires due to its large area of flammable plants, said Lincoln University senior ecology lecturer Dr Tim Curran.
Older gorse plants in particular were highly flammable, as was bracken, pine trees, and native kanukas.
"You've got a fuel mix there which means large chunks of the Port Hills and the Banks Peninsula are actually covered in this quite flammable vegetation," he said.
"If you get an entire tree going up you're going to get a very intense, hot fire. If the fuel is continuous enough you're going to get a canopy fire, which is what we've seen.
"You've got the fire moving through the canopy, so it gets very hot and can burn very quickly and can be quite devastating."
He said it was worth considering ways to reduce the flammability of the vegetation on the hills.
As the destroyed plants re-grew, it was likely the area would look different in the short term.
"There will definitely be some short term changes to the vegetation, but over time it may start to return to these communities or even go off and form what are known as novel ecosystems - new mixes of species we haven't seen before."