Fire Ecology

In wildfire risk control, 1 ‘size’ may fit none

By Mitch Tobin 

As the blame game continues in the wake of the disastrous Rodeo-Chediski wildfire, experts on fire ecology say they have scant research on a problem that may get worse in the Southwest.
Scientists in Tucson this week for the annual meeting of the Ecological Society of America said many parts of the West are vulnerable to unnaturally intense fires because of a solid century of human influence.
So it’s impossible, they say, to pick out a single cause for big blowups like the one in the White Mountains, or to prescribe a one-size-fits-all strategy for reducing the risks. In some cases, logging, brush removal and prescribed burns may lessen the hazard, but in other cases the treatments will fail.
“The thing that troubles us as fire ecologists is how grossly oversimplified the reasoning is, not just on the part of politicians, but by the general public,” said Paul Zedler, an environmental science professor at the University of Wisconsin-Madison. “That’s understandable because fire is such a complicated subject.”
It was only a half-century ago that ecologists conceived of fire as an external shock to the system, rather than a normal part of the forest’s life. Now, fire is accepted as a natural, cyclical factor that helps explain the distribution of various tree types.
But despite the federal government’s spending billions in recent years to fight fires and rehabilitate burned areas, the researchers said they still have far more questions than answers about fire and its effects.
In a sobering assessment of the current scientific literature on fires, Edward Johnson of the University of Calgary said researchers have published hardly any studies on:

* How ground fires rise to become the devastating crown fires that sweep from treetop to treetop.

* How the thunderheads created by rising smoke spread a fire with convection currents.

* The relative importance of fire suppression and land use changes, such as grazing and logging, in explaining fire behavior.

* What causes fires to go out.

* The effectiveness of fire suppression techniques.

At least $18 million will be spent to rehabilitate lands burned by the Rodeo-Chediski Fire, but researchers said little is known about the effectiveness of seeding slopes with grass and applying mulch to reduce runoff and erosion. Many also question the ecological wisdom of applying non-native grasses after fires.
After the 2000 Cerro Grande Fire near Los Alamos, N.M., the federal government spent twice as much on rehabilitation as it did fighting the fire, said Craig Allen, a U.S. Geological Survey researcher who was part of the recovery team. Crop-dusters applied 3 million pounds of mulch to steep slopes to prevent erosion, but it looks like the effort failed, Allen said.
This year in New Mexico, scientists wanted to study post-fire recovery techniques. But they couldn’t get 10 acres set aside as an untreated control because officials feared political fallout from downstream communities.
Despite the gaps in knowledge, some things about wildfires are clear, the scientists said in a consensus statement issued Monday.
In the ponderosa pine forests common to Southwest mountains, intense crown fires were historically rare because periodic, low-intensity ground fires consumed fuel before it built up. But with aggressive fire suppression over the past century, ground fires have nearly disappeared and forests that were once spacious and parklike are now choked with “doghair thickets” of young trees that provide flames with ladders to the forest canopy.
While stand-replacing crown fires are abnormal for ponderosa pines, they are a natural part of higher elevation spruce-fir forests and lower-elevation chaparral. “Eliminating crown fire in these ecosystems is not feasible nor ecologically warranted,” researchers said.
The ecologists’ statement favored cutting some small trees and removing brush around houses, but it stressed, “In some ecosystems it would accomplish little, and in others in which it could be beneficial, costs will be prohibitive.”
Commercial logging of forests can sometimes reduce fire risks, the researchers said, but chopping down old-growth forests is pointless since they are limited in area and are the least susceptible to crown fires.
Because it has taken more than a century for fuels to accumulate in Western forests, the scientists said solutions will be neither quick nor cheap.
“In coming years we’re going to see, I’m afraid, more Rodeo-Chediskis,” said Tom Swetnam, director of the University of Arizona Tree Ring Laboratory.


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