JEMEZ SPRINGS – Tom Swetnam was pumping gas at the station across from Los Ojos bar in the summer of 1971 when he saw the mushroom cloud of smoke boiling up over the walls of Jemez Canyon. The 15-year-old’s first thought: “Oh, my gosh, Los Alamos just got nuked.”
It took a moment for him to realize it was in the wrong direction. No Los Alamos nuke. Wildfire.
The son of the National Forest Service’s Jemez district ranger, Swetnam grew up with a hand-cranked phone in the front bedroom, hardwired to the fire tower. “All through the early 20th century Forest Service, their mission was to put fire out, and I grew up with that,” Swetnam said.
“Our life, especially in the summertime, was looking out for fire,” Swetnam said. “Fire was bad.”
Today, Swetnam knows better, though the view four decades later is complicated. Healthy forests need fire. The kind of conflagrations we are seeing on New Mexico’s landscape can be devastating, but low-intensity fires are essential.
Driving north out of the village of Jemez Springs recently, Swetnam pointed to canyon walls overgrown with Ponderosa pine thick as the hairs on a dog’s back. Past the little enclave of La Cueva, Swetnam turned his Toyota Tundra, chainsaw in the back, onto a jarring dirt road through the woods. To the east, smoke curled into light afternoon winds, rising from Redondo Peak, as the Thompson Ridge Fire spent an afternoon creeping through the forests of Swetnam’s youth.
Without the precise aerial imagery and mapping software used by the 21st century wildfire community, it is impossible to say with precision how much the Cebollita burned in its 1971 trek across the Jemez mesas. The best estimates put it at between 3,000 and 4,000 acres, small by the standards of today’s Southwestern wildfires. This year alone, New Mexico has already seen four fires larger, the nearby Thompson Ridge among them.
But in 1971, the inferno of Cebollita left a much larger mark on the Jemez. At the time, it was the largest fire the mountain range had seen since firefighters began snuffing out blazes in the early 20th century. Fire was returning to the mountains with a vengeance.
In a contemporary newspaper account, Swetnam’s dad, Ranger Fred Swetnam, called it a “fire storm.”
“It was like a monstrous serpent writhing and twisting in the air,” the elder Swetnam told a reporter.
On his recent return, the younger Swetnam recalled the chaos as the Cebollita crested a ridge above La Cueva. Busloads of firefighters filled the camp, and helicopters and slurry bombers filled the sky.
“It was like a war scene,” he recalled.
The ten o’clock rule
In the wildland fire community, they called it “the ten o’clock rule.” At the first sign of a spark, firefighters would swoop in, with the goal of putting out every fire by 10 a.m. the day after it was spotted. It dominated U.S. forest policy for much of the 20th century.
That’s what Swetnam signed up for back in 1978 when, after getting his degree in biology and ecology from the University of New Mexico, he signed on to a “helitack” team on the Gila National Forest in southwest New Mexico. Sweeping in from the air, the crews became part of that war scene that so impressed him as a teenager – air assault, putting out fires fast.
But by his third season as a member of the Gila Hotshots, Swetnam was beginning to see change. Forest managers saw problems created by their enthusiasm for fighting fires. Overgrown woods began burning with increasing ferocity once they did catch fire.
At first tentatively, managers began looking for opportunities to let fires burn. Instead of rushing in to put it out, Swetnam’s crew in some cases now just watched. “I got to go out on horseback and monitor the fire that was burning in the wilderness,” he said. “That was fantastic.”
Growth of ‘doghair’
The chainsaw in the back of the Tundra is one of the tools of Swetnam’s trade. The Arizona license plate on his truck reads DENDRO, short for “dendrochronology,” the use of tree rings to tell stories about the history of ancient forests.
Tromping through an overgrown thicket of spindly Ponderosa pines on the edge of a fire scar atop Virgin mesa, Swetnam expertly flipped over an old downed tree and pointed to fire scars burned into the bottom of its trunk.
After three years as a firefighter, Swetnam and his young family moved to Tucson, where he began working on his doctorate at the University of Arizona, studying the fire history of the Gila.
Today, Swetnam is a professor at the University of Arizona and director of its Laboratory of Tree-Ring Research, where he has been one of the pioneers in the use of trees like this to reconstruct the history of fire in the forests of the Southwest.
What the scientists have found in the years since a young Swetnam watched Cebollita Mesa burn was at first surprising.
On the base of the downed log, Swetnam pointed to the marks left on the old tree, where fires had repeatedly burned around its base, scarring it without killing it. Slices of downed trees like this, chainsawed in the field and hauled back to the scientists’ Tucson lab, reveal a story of a landscape that in centuries past burned frequently, once or twice a decade.
The fires burned along the ground, with flames a foot or two high, clearing out the little stuff. Left behind were big, hardened, fire-adapted trees in open, parklike settings.
After a millennia of that, the fire record for the Jemez Mountains stops around 1900, with the only fires after that tiny dots on the landscape as the ten o’clock rule took hold.
“Really frequent surface fire was the norm in these Ponderosa pine landscapes,” Swetnam said. “And then, right around 1900, they stop.”
Unhindered by fire, trees grew to fill in the gaps. Forest hands call such thickets “doghair,” and they are everywhere in the mountains of New Mexico. Instead of burning lightly across the ground, fire easily rises in doghair into the trees’ upper branches, their “crowns,” where it can explode into a widespread, forest-killing blaze.
Mapping the fires
Kay Beeley, part of a research team based at Bandelier National Monument, has built a series of historical maps of fire in the Jemez Mountains. Early in the 20th century, her maps show little more than a splotch here and there, the result of fire suppression stopping fires before they spread.
By the 1970s, firefighters start losing ground. Cebollita, the fire that so impressed a young Tom Swetnam, is one of three good-sized blazes that decade, but they look tiny compared to what came after. The 1980s were a wet decade, with little fire. But then, as you flip through Beeley’s maps decade by decade, the mountains seem to explode.
“Now, in the last 20 years or so, 30 years, we’re getting these conflagrations, these big, high-intensity crown fires,” Swetnam said.
And it is not just that more acreage is touched by fire, Swetnam said. The buildup of fuel, combined with drought and rising temperatures in a warming world, have turned fire in the mountains where he grew up into something completely different.
Las Conchas, the 2011 fire that at the time was the largest in recorded New Mexico history, marked a turning point. In its first day, it burned 10 times the area in the entire Cebollita fire of 1971. It spread so hot and so destructively that, after a post-fire visit, Swetnam described the landscape as “nuked.”
“No firefighter, I think, in the Southwest has seen that kind of fire behavior,” Swetnam said.
And that, Swetnam suggests, poses the central dilemma. The only way to prevent huge, destructive fires, he said, is to find a way to return natural fire to the system, clearing doghair where we can and finding ways to allow more natural, low-intensity fire to coexist in the woods with the people around them.
As Swetnam spoke, the Thompson Ridge Fire burning on Redondo Peak behind him captured the dilemma. Some dense, unhealthy patches of forest burned catastrophically, with fire destroying everything in its path, Swetnam said. In other places, including some areas where forests had been cleared, the fire dropped down to the ground and crews had to merely surround it and let it burn itself out.
“Is fire good? Is fire bad?” Swetnam asked. “Yes. Both.”