Fire Season

Wildfires have sprung up early this year and the cost of extinguishing them is growing exponentially because these days there is much more urgency to extinguish them. Helicopters with monsoon buckets are arguably the most useful tool, but they are expensive.  Back in the day when we were burning off large tracts of land in preparation for planting, we gave no thought to the emissions into the atmosphere. And still today I think as a nation, we can reduce emissions until we are blue in the face, but it just takes a volcanic eruption or wildfires elsewhere in the world to undo all that saving.

Our thinking was somewhat different back in the day because bringing fires under control became a matter of working out the options and priorities. We didn’t have the use of helicopters and our fire tanker had four minutes’ worth of water, and our vehicles plodded along without the speed of modern vehicles. Shovels and beaters were our standard equipment. We had dew ponds, but during dry times, they lacked water. But we learned about fire behaviour and how geography and weather played their part.

There was a wildfire on the shores of Lake Wanaka, the other day. It started at the bottom of the mountain and raced to the top. We would have had to allow the fire to burn up the mountain face, because putting manpower in front of a fire is stupidly dangerous. At the top of the mountain, the fire is likely to go out through lack of fuel and the rising oxygen on the slope would be no longer be feeding the fire. It may keep going burning down the other side, but those fires are slow and easier to stamp out. On a mountain slope, it was best to fight the fire on the flanks. A fire will flare, and then go down before it flares again, men just have to wait for the blaze to go down and then attack it.

These days it is possible to fight a fire on the mountainside using choppers, and depending on the situation, there is usually a rush to put it out. Firefighters have to consider the public perception, people think a wildfire needs to be attacked straight away, whether or not the action is actually doing any good in the greater scheme of things. They are also concerned about pollutant emissions.

A major contributor to wildfires is of course fuel. In past history, the mountains were under grazing leases, and to stimulate fresh, green grass growth, farmers burnt off the areas regularly. But, and fair enough, the grazing leases have been cancelled, so there is no controlled burning, therefore there has been a buildup of fuel and incidentally, wildling conifers. So when a fire does start, it is much more vigorous, creates larger flames and the general public worry more. The other need for urgency is that these days people like to build their houses within bush areas, so it comes down to the protection of property.

How do wildfires start? Well, there are the dingbats who light them! Some malicious, some accidental, some through sheer stupidity! Let’s not dwell on them. Lightning can cause fires, so we can put some down to Mother Nature. Here are a couple that I was involved with.

We had been planting at the Forest and Range Experimental Station, Craigeburn and were just part-way through our last day there when we noticed smoke. There was a grazier, but for the last three years he wasn’t allowed to burn, so there was a lot of fuel. We rushed back to the headquarters and found out later that John, who was on kitchen duty, had burnt the last of the rubbish, ensured it was out safely and covered the fire with rocks. Cleaning up, he found a Rinso packet. Rinso was soap powder used for dishes and laundry, it came in a cardboard box, much like a cereal packet. He decided to burn it, and as he watched a gust of wind picked it up and deposited it in tinder dry grass twenty yards away.

I should explain; the East side of our Southern Alps is a rain-shadow area. Worse, the effect of moist air from the Tasman Sea, rising and with altitude, losing its moisture, warms the air and so the North West winds are strong and warm with very low humidity. In those conditions, the fire danger becomes extreme.

At the time the wind was only puffing, but the humidity was low. The fire had burnt thirty five acres and we were pinching off the last little front. My team on one flank and another on the other flank. We had just twenty yards to meet and the fire would be out! The fuel was just three-year-old tussock, but the Nor’wester suddenly grew in strength and the fire gathered pace so we failed to pinch it off! The fire burnt rapidly and extinguished itself at the main road and a green lucerne paddock. It burnt over two hundred acres in a matter of minutes. The farmer was happy enough, he would have green fodder in a few weeks’ time!

I was in charge of a burn-off of around two hundred acres, which was the whole catchment of a small creek. We carried out the considerable preparation for the burn and while it is foolish to light up in volatile conditions it is also important to consider that a hot fire is needed to ensure a clean burn. More cost is involved if there are unburnt gorse sticks or slash. So while the forest enjoys one of the drier microclimates within the country, being close to the sea means the humidity can be too high for a clean burn, so it is best to wait for a northwesterly wind to die down before a change to the southwest. The burn was going well, but the northwesterly kept puffing, which was against the forecast, and the humidity was still dropping. Such conditions quickly become unpredictable. I had Ralf and his crew station on the southerly edge of the burn in case the fire jumped across the road. I pulled up in my vehicle to check, and they had laid out the hose and were prepared. A single red-hot frond of bracken fern landed exactly where the hose had been laid out, on the green grass. Green grass can usually be counted on as a firebreak, but not this time, that small fern-frond sprung into life setting fire to the green grass that had desiccated in the heat! All Ralf had to do was pull the cord on the pump motor. The fire quickly became so hot that we had to move the vehicles and the water from the two inch hose evaporated before it reached the seat of the fire! The wildfire scorched along so we attacked the fringes, but the main area that was burning was downhill and in the lee of the wind, so it was out by nightfall.

This demonstrates how easy fires escape in volatile conditions, it might well be exciting to see big flames and helicopters dumping water from monsoon buckets, but it’s dangerous work and an expensive operation – always someone pays! Fires are also devastating on wildlife. When the fire danger is high, don’t light any fires, even if you think you are an expert or are experiencing extraordinary circumstances!