Friday, 17 February 2017

The Port Hills Fire

For those who don’t know much about my little corner of the world, Banks Peninsula sticks out of the eastern coast of Te Wai Pounamu – more commonly and prosaically known as the South Island of New Zealand. To Māori, the Peninsula was Te Pataka o Rakaihautu.

Captain Cook, named what he thought was an island after naturalist Joseph Banks and it was once an island until the great rivers that flowed out of the Southern Alps deposited enough gravels and soils to join it to the mainland.

It is the twin craters of ancient volcanoes whose seaward sides have been eroded through to the crater hearts, creating two deep-water harbours – Lyttelton and Akaroa – along with many other bays and inlets. The Māori name for Lyttelton harbour is Te Whakaraupō - harbour of the Raupō  - reeds that once filled the marshy area at the head of the harbour.

Before European settlement the 1150 square km peninsula was still largely forested with tōtara, tī kōuka, kahikatea, mātai, akaake, miro, puruhi, houhere, kānuka, mānuka, harakeke, tarata, kōhūhu, korokio, koromiko, nīkau, mānatu, makomako, whauwhaupaku, horoeka, horopito, matipou, kawakawa, rōhutu, karamū, tītoki…..and many other trees, shrubs, flaxes and grasses which formed the diverse coastal and hill forests that blanketed the land.

Most of this glorious and diverse forest was lost in the first 50 years of European settlement - either logged or burned. The Canterbury Plains and the Peninsula are among the most altered landscapes in one of the most rapidly altered countries in the world.

Along with the forest went the millions of birds that depended on it; and with the birds went the nutrient rich droppings that fed the bush and the soils that overlaid the igneous rocks. The land that the logging and fires exposed was mostly very steep and deeply folded having been formed by lava flows.  Many of the streams that trickled out of gullies dried up once the bush had gone.

Many of the old hill farms on the peninsula were marginal because the land is so steep and folded and, because of the loss of the deep damp litter of the original forest floor with nutrients provided by the droppings of millions of birds, the soils quickly lost heart. The loess erodes in the wind and rain and it dries out fast and hard. In light rain the exposed soil turns as slick as ice and in heavy rain into a sticky porridge.  Holes in the volcanic rock can collapse and trap animals. They can also harbour fire.  

The fire risk was massively increased when settlers planted fast growing gorse and pines to try to stabilise the land and to give shade and shelter to, and contain sheep and cattle.  Gorse quickly became a very harmful noxious weed because in NZ it flowers almost all year round, is highly flammable, broadcasts its fire resistant seeds widely, and nothing eats it.  Pines, which  tend to poison the ground beneath them, are invasive and flammable and co-exist very happily with gorse which colonises pine forest margins and spreads to open land.

The part of the peninsula to the south of Christchurch / Ōtautahi is known as the Port Hills which form a 300m barrier between the city and the port.  There are three roads into and out of the port other than the road tunnel: Evans Pass, which went up from Sumner and came down into Lyttelton from the east and was so badly damaged in the February 2011 earthquake sequence that it remains closed on the Lyttelton side; Dyers Pass, which runs over to Governor's Bay and is closed at the time of writing this because of the fires; and Gebbie’s Pass, that runs in through the low hills at the head of the harbour.

The scenic Summit Road which runs along the crater rim was meant to have a series of tea shops named after native birds of which only three were ever built and two remain.  The Summit Road was the creation of the visionary, Harry Ell. 

The three road passes and the Summit Road give people access to a wide variety of walks and bike paths on the hills and to the numerous small communities that have grown up in the bays around the harbour. 

It is fair to say that the Port Hills and the peninsula more widely, occupy a special place in Christchurch history and in the hearts of most of the people who live there.

Generally Christchurch turns its back on the sea because of the prevailing strong and cool on-shore easterly winds, and the city’s eastern suburbs are largely working class.  The hills have always drawn the more affluent and their interest pushes up the price of land. People have built homes on the hills and cliffs above the small Christchurch seaside suburbs of Sumner and Redcliffe and along the roads that lead out there from the city for generations because of a microclimate and the spectacular views across Pegasus Bay and / or the Southern Alps. 

The new housing developments west of the older hill suburbs are the latest encroachments on the hills, with higher density housing on the lower slopes, and lower density housing further up where the views are the best.

In addition to the encroachments of housing, some of the old hill farms have been subdivided into what are known in NZ as ‘lifestyle blocks’.  Mostly the people who buy these blocks have to work to earn the money to live on them, which is why they’re often referred to as ‘life sentence blocks’.

These blocks range in size from .5 of a hectare to 25 or so hectares, after which they become small farms.  Lifestyle blocks tend to have smaller paddocks than hill farms and the owners plant more trees – which is a good thing except they tend to plant fast growing exotic species like pines, conifers and gums.

The grass cover throughout Canterbury this time of year, other than the land under irrigation for dairying, is tinder dry. If grass is left long under fences - i.e. not grazed hard by sheep or sprayed, fire will track along fence lines igniting fence posts. These posts are treated with highly toxic chemicals that are released into the atmosphere when burned and fire can also smoulder in them underground.

There’s an increased fire risk from overhead power lines shorting onto trees or if a transformer is overloaded and blows, or when electric fences short onto dry vegetation – as well as sparks from exhausts, mowers etc.

Although Christchurch got normal rainfall over the last year it wasn’t enough to replenish soil moisture levels depleted by preceding years of drought. We’re in the driest part of the year so trees are stressed, leaf dries out and falls early, the litter on the ground becomes tinder dry and - wherever the sun can get at it - very hot.  It takes very little to ignite it. 

All vegetation will burn in certain conditions - anyone who has burned gum tree slash will know that even when green and soaking wet, once the water evaporates and heat gets to the oils in the leaf, it will explode.  The same with pines and gorse.  Arguably the key element in this fire was the heavy fuel of mature pine trees. All the really big wildfires in NZ have been in pine forests and most of the ones in the South Island have occurred in February. 

The Port Hills now have extensive commercial pine plantations, a lot of it owned by companies like McVicars, which owns the land the new Canterbury Adventure Park is on.  Commercial pine planters are notorious for not cleaning up litter from trimming trees or after logging. They’re not required to provide things like storage ponds for firefighting and their attention to fire breaks may not be all it should be.

The Fire

I first heard of the Early Valley fire at 6.30pm Monday and it had been burning for a couple of hours or so by then. A strong north-west wind was blowing that was forecast to blow all night and the following day.  

The Canterbury nor-wester is a foehn wind – dry, hot and powerful. That wind, plus tinder dry conditions and decades of poor land management, provided the conditions in which a fire  - if it got away – had the potential to roar right across the very steep pine, grass, gorse and bush covered hills. 

I had an ominous feeling that the fire was going to be a bad one. That feeling became worse when I heard about a second fire on Marley Hill to the east. Fire can’t be fought from the air at night or in low cloud cover and with power pylons and convection currents it’s highly dangerous even in daylight. The nature of the fire meant it was almost impossible to get in front of it from the ground.

If I, as a lay person, could work out that this first fire needed to be hit with everything that could be mustered while there was still daylight - how come the people managing the fire seem not to have done the same?  

I don’t mean the people on the ground - for whom I have nothing but praise - I mean those people whose job it is to assess the situation and deploy the necessary resources as rapidly and effectively as possible.

The situation seems to have been exacerbated by the intrusion of jurisdictional issues.  The rural fire chief who made the statement on TV that the rural service knows how to deal with rural fires while the urban firefighters just rock up and plug their hoses into a hydrant - may have betrayed a schism that has no place in an emergency service at any time, let alone when facing a fire of this magnitude.

It also exposes New Zealand’s rigid bureaucracy, which too often leads to an inability to respond fast and effectively.  In rescuing and housing animals, catering for exhausted firefighters, offering accommodation for evacuees and their animals - the public was sprinting far ahead of the authorities in the first two days.

The first responders to the fire were the professional firefighters from Christchurch city and they and various members of the public fought the fire initially but were struggling to contain it.  They had been deployed because the fire was at the edge of the city and there’s always a delay with the rural fire service because volunteer firefighters have to get from home or place of work to fire stations, get geared up and get to the fire.  The professionals from Christchurch were stood down and - because the fire was within Selwyn District Council boundaries - the Selwyn rural fire service then led on it.

By the time the second fire was reported further east along the Summit Road within city boundaries - it was too late to hit either fire with helicopters or fixed wing planes so both fires burned out of control overnight gathering massive energy and momentum. The two fires eventually joined up and the cold air sinking into valleys at night took it back down the hills and onto houses.

As to the anticipated wind change to north-east on Wednesday that the person leading on the fire hoped would blow the fire back onto already burned land - I’m not sure how a north-easterly wind would blow a north-westerly driven fire back on itself and it seemed to take no account of the fact that the second fire was to the east of the first. That aside, given the vagaries of convection currents in steep folded land and fire’s propensity to take lines of least resistance, it was obvious it was already in a state of extreme unpredictability.

This was not the biggest wildfire in NZ's history - what made the Port Hills fire so dangerous was that it was just 6 kms from Christchurch city centre.

If we are in an era of climate change driven east coast drought and increased fire risk, then these jurisdictional issues need to be sorted out and our reliance on volunteer fire services on urban margins may need to be reviewed. 

I’m not taking anything away from the volunteers of the rural fire service - they do an amazing job - but this situation exposes the logistical absurdity of rural versus urban fire services on city margins and of artificial lines of territorial demarcation.

Individual landowners' responsibility to minimise fire risk will need to be clarified and enforced - especially large scale commercial planting of exotic trees. One of the main problems in fighting this fire was finding sources of water for monsoon buckets. It seems ludicrous that an individual or a company may plant massive pine plantations on the hills above a city and its satellite settlements but not be required to build and maintain fire breaks and create water storage for fire fighting.

My father farmed on the eastern bays of the peninsula years ago and I remember his diatribes about bad land management and the horrors of a mix of dry grass, gorse, wilding pines and gums.  This fire was a disaster waiting to happen.  Of course native forest will burn but it is not as flammable as bone dry pine, gum, gorse, dry grass and houses. 

We destroyed the vast bulk of the original ecologically balanced forest cover on the peninsula. Pockets of it survived in gullies and dedicated people have invested lifetimes of work trying to protect and extend those pockets, control predators and encourage native bird populations.  A fair bit of that regenerating bush has been destroyed and that’s beyond heart breaking.

There’s a battle going on for the heart and soul of the world, which this situation exemplifies - between those who want to sustain, nurture and co-exist and those who see the world as something to be pillaged for short-term gain, and/or as their playground.

1 comment:

  1. Hi there Lynn,
    Thanks for that very complete account which included the great taboo subject of climate change.
    I live in Heathcote and noted the length and dryness of the grass earlier this year. The seeding grass gave the hills an unusually light brown appearance. I said to a number of people that I thought the fire risk was unusually high. But I had no idea it would happen this way because this fire was of a different magnitude of intensity than any of the hill fires I’ve seen over the years.
    I thought and read a bit about the flammability of various plants and trees, as well as the many possible ignition sources. It seems likely that most of the fires we see start in long grass or dead foliage near roads and human habitation.
    So, I think it comes back to land use and the dangerous mix of the remnants of grazing blocks and lifestyle blocks. Given the number of humans in the vicinity, it would be difficult to eliminate all the sources of fire (though this should be addressed as well).
    The best suggestions I've seen are "fire zones" where high risk areas are required to take fire prevention measures. The other one is that we try and restore the native bush and ensure that these regenerating bush areas are somehow protected though buffer zones of fire resistant species. There has been quite a bit of work on the flammability of various native and exotic plants which should be drawn on.
    The related issue on the hills is soil depletion and erosion. The more recent land uses all cut into the steep hills and accelerate loss of fertility and erosion. There are many ‘under-runners’ in Heathcote Valley that run for hundreds of metres and large sections of slumping land. So much of the flooding problems we are having are related to the huge quantities of soil washing into drains and waterways.
    There have also been suggestions of an urgent review or inquiry into fire danger and a sustainable strategy to counter the increased risks. I feel a bit sceptical about these measures happening when so much of local government and the general population are still lagging so far behind on climate change and there is such poor leadership from central government.