Back in the 1990’s, I was a camera operator on a wildfire experiment. The Northwest Territories’ wildfire team conducted burn tests on sections of forest to see how fire burned through different kinds of live wood fuels. Outside of Fort Providence, there were four large square plots of forest, each about 10-20 metres high. Some were dense forest and some had open areas. The plots were different combinations of evergreen trees with needles and deciduous trees with leaves. They were neatly shorn from the rest of the forest with breaks so technicians could move around them on all-terrain vehicles.
When a gentle breeze wafted in a consistent direction, the signal was given. A helicopter hovered in quite slowly towards one edge of a plot. Slung below the helicopter, was a long line with a small device which dripped a glutenous material that was burning. This ignited the forest floor. Sometimes they lit just a corner of the plot. On other plots, the helicopter dropped a line of flames along the whole flank of the square to replicate an approaching ground fire meeting the whole stand at once. The plots were burned one at a time.
The conditions were right. With the coniferous tree plot, the pine or spruce, the fire caught quickly. It wasted no time and raced up the trunks. It leapt even a bit higher into the air. It moved fast from tree to tree and it wasn’t clear if it was spreading between the tops, trunks or along the ground. That plot was quickly and intensely ‘all on fire'.
It was a carefully planned experiment and so plenty of fire suppression equipment was readily on hand. Each plot was extinguished fully after the data was recorded.
I was filming from another helicopter. We gently moved in over a plot which was a combination of different trees. We were high up, maybe 100 metres to stay clear of the heat. But I had a good zoom lens. The ignition helicopter was underneath us and it lit the edge of the stand before drifting out of my camera frame. The bright green leaves of aspen, alder or birch were bunched at the opposite end from the flames that were taking hold. My helicopter gingerly pivoted and in a parallel arc over the treetops, we followed the fire’s development. It again raced up the coniferous trees and with that steady breeze, moved through the stand in just a couple minutes.
But then, there was something I did not expect. The fiery advance wavered a bit. Had the wind changed? Was there a hidden swamp in there? It slowed right down. The flames lapped in the air a bit and then withdrew down the trunks. It was suddenly and surprisingly out, except for a bit of smouldering. It was astonishing. The bunch of leafy trees stalled and then extinguished the flames.
The scientists anticipated something like this, but the footage was so punctuated, so immediate and definitive. Despite the wind and flaming conifers right beside it, that part of the forest did not burn.
This marked the beginning of my interest in what is known as fire ‘behaviour’.
Fire is puzzling. Harkening back to childhood Thanksgivings when Uncle Peter mesmerizingly swiped his finger through the candle flame had me wondering for quite some time, "what is it?" It seemed dangerous and cool at the same time. I mean there it is, intentionally on the dining room table atop six tapered spindles of wax. But then, if we brush a candle with a napkin – Oh no - how things get quite out of hand!
Transpose that to our lifestyle here where the campfire warms the stew and aching shoulders from a long day’s paddle. But if the wind whips up the not-quite-out embers, we can have a major problem in no time.
Fire is the result of a chemical reaction when a material combusts and that is when its electrons rapidly break away due to very high heat. The material disintegrates and ‘fire’ is the visible part of the reaction. It’s sort of a streaming hot gas that keeps consuming materials around it.
It needs continuous heat and oxygen and something to combust (fuel) to keep going. Remove (or hamper) any of these and it goes out. The change in the tree moisture in the plot experiment changed the fuel and lowered the heat. It made it go out.
When we control fire it’s useful. But out in the open, fire can look like it kind of controls itself.
When it’s big, it’s frightening. The media shows us the towering billows of smoke stacked up to the sun on rolling mountain ridges, where fire is like a long advancing ribbon on the land. But fire doesn’t just rage. It can also creep. It hides out in disguised ashes. It pops and sparks. It can slither through grasses. And it has a long reach through embers in the wind. It can leap ahead of the current blaze and advance itself. It can create heat strong enough to combust materials without directly touching them. It crackles and fells trees. It even goes around dampness. Fire seems to be opportunistic.
In a way, this could be because fire has a natural role. It is meant to be able to spread. It plays an important part by regenerating the forest. The earth and sky conspire with an ignition signal – lightning, and that gets it going. It burns up old debris and creates a charred open area that invites in sun and moisture. Plants and animals come in. Pinecones open and release their seeds in the intense heat. The forest comes back.
The trouble is, we’re in the way. Our land, buildings, and towns are in that boreal forest zone, right in the path of fire. Not being nomadic, I have to think about fire and what to do about it.
I live in the valley which could very well be the direction from which a wildfire finds Whitehorse. Prevailing winds are southerly, sailing up from both British Columbia and from American mountain passes, converging at Carcross and then northward to the capital city.
But then again, maybe not. In 2023 an Ibex Valley fire, north of the city, activated concern for Whitehorse and a 1991 fire lapped at homes in Crestview coming down from Haeckel Hill. These old mountain ranges flanking Whitehorse funnel our fire consciousness and keep us alert.
I’m heeding the advice of the experts and I do a little something each year to improve the defences around my home. Here comes our summer season and I’m eyeing how to enjoy the land and, I hope, the sun. But my other eye is on the ‘what if’ of the situation.
I remind myself how I feel in October, when I’m breathing a sigh of relief that I didn’t experience the threat of a major wildfire, but I’m tuned to the fact that other Yukoners might have. I feel I owe it to them and to the citizens of Fort McMurray, Lytton, Yellowknife, Enterprise, Jasper, Kelowna and Los Angeles to get prepared.
This season, I’ll explore and share the challenges and good ideas encountered while getting ready for the risk of fires.
Ross Burnet lives in the boreal forest just outside Whitehorse. For 25 years, he’s been thinking about how to defeat embers. He will explore wildfire and how it can be prepared for in a column published every three weeks this summer.
