Underburn

libburn

Once upon a time, in the 1980s, my primary job involved prescribed burning (lighting fires under prescribed conditions). There are many reasons to do this: burn tree limbs and tops on the ground after logging to create spaces for trees to be planted and to reduce the intensity of any unplanned fire that might come along; to kill less preferred tree species and maintain a more “natural” regime of fire in the forest; to stimulate growth of forage and browse for wildlife. Certain aspects of working with prescribed fire were right up my alley–being outdoors, observing a natural process, collaborating with others. The more time I watched fires burn in the woods, the more I made connections between the variables that influence fire behavior such as terrain, weather, speed of ignition, fuel loading and so on. Endlessly fascinating.

But life changed and I moved onto other things. In the subsequent years, I’ve had many opportunities to stay marginally involved with fire in some capacity. My experience as a lookout and observer is unusual in the 21st century Forest Service. Firefighting has grown more exclusive and high-tech. And our culture doesn’t exactly encourage patience, solitude, and attention.

So last week I was surprised by the invitation to go out and do what I do. I made weather observations before the test fire was lit, then documented the fire’s progress with notebook and camera. I heard the familiar zip of flaming fuel whizzing out of the end of the drip torches as the lighters tipped them into piles of sticks on the ground. There was a cheerful crackling. Voices. The smell of wood smoke. The incessant whine of the Mark III pump sending water along fire hoses so the holding crew could spray down adjacent trees to keep the fire where we wanted it. I paused to measure rate of spread–how fast the fire moved forward and how fast it backed down the hill. Conditions were just right. Just enough wind. Just enough relative humidity to counteract the rising temperature. The lighting was finished by noon, and the top of the fire was dying down. Smoke billowed up Pine Gulch, more or less away from nearby cabins. The objective of this fire was to reduce flammable material up to the National Forest boundary. Beyond it lies private property, residences, mines. Things that are of high value, that cause us all to worry when wildfire is afoot. The acronym is WUI (pronounced WOO-ee)–Wildland Urban Interface.

My work was done by early afternoon, and the crew was mopping up–cooling the fire’s perimeter. The Mark III whined on. This coming week I’ll go back to take some post-burn measurements, and write my report complete with hand-drawn map. How much of the ground fuel was consumed? How far up the trunks of the residual trees did the fire scorch? Were any areas left unburned? Did any areas burn hotter? We shall see.