There is a sharp dividing line between what works, and what doesn’t, in managing the forest.
It is Forest Road 25 deep in the Fort Apache Indian Reservation.
On one side of the dirt road, the tribe had recently completed an aggressive forest thinning project to remove thick stands of trees and clear excess debris from the ground. They had planned similar work on the other side, but had not gotten to it.
When the Rodeo-Chediski fire burned through the area last June, it raged in the crowns of the untreated stands of trees, leaving nothing behind but a ravaged moonscape.
Once the fire crossed Road 25, it hit the treated areas, dropped to the ground and burned itself out, returning to what is considered normal and healthy fire behavior. It singed the grass, but left the trees green and healthy.
"I was expecting it would be a lot worse," said Robert Lacapa, a tribal member and the U.S. Bureau of Indian Affairs’ forest manager for the reservation. "I was really caught off guard in regards to what we saw out there. I knew instinctively that it was our management treatments and what we had done that allowed us to be able to have these areas still in the green. I wasn’t a true believer before. But when it’s tested, by golly, it does work."
If there is one proven truth from the Rodeo-Chediski fire it is that forest thinning works, according to Lacapa and others who say large-scale treatments are needed immediately. That was proven repeatedly in the 2002 wildfire season. Fires that threatened communities were stopped near Prescott and near Pine when they hit small areas that had been treated, according to Forest Service officials.
Nowhere was the difference more stark than on the Fort Apache reservation, where the Rodeo-Chediski fire began. Areas that had been recently thinned were largely undamaged while those that had been left untreated were destroyed, Lacapa said.
Despite its successes, thinning is still being done only on a small scale in Arizona. Last year, 41,568 acres on the national forests were given some type of fuel treatment at a cost of $9.5 million, according to Forest Service figures. That includes such things as prescribed burning to clear underbrush and debris on the ground. It also includes treatments in grasslands. There are 11.2 million acres of national forest land in the state.
Even if the forests stopped growing, it would take almost 40 years to treat the 1.65 million wooded acres in Arizona at high or extreme risk of wildfires at the current rate.
That pace is unacceptable, said Wally Covington, a professor of forestry at Northern Arizona University.
The forests are so overgrown with trees that the land can no longer sustain them, Covington said. Where the land might have carried 50 or 100 trees per acre in its natural condition, there are now many hundreds, in some place thousands, that are competing for water and nutrients, he said.
Some places of the Apache-Sitgreaves National Forests had as many as 3,000 trees per acre before the Rodeo-Chediski fire, according to Forest Service estimates.
That overstocking leaves the trees weakened, unable to ward off insect infestations and ready to explode into a wildfire, Covington said.
Covington’s "presettlement model" is based on the concept that the forests are in such bad shape because of more than a century of mismanagement that has created unnatural conditions.
Aggressive fire suppression has altered the natural process in which periodic, low-intensity fires burn across the ground, killing off smaller trees and burning excess debris, Covington said. Now the forests are so overgrown that fire cannot be safely reintroduced until the forests are thinned to a more natural state, he said.
THINNING THE DANGER
The concept of thinning is simple enough.
It involves cutting out thickets of nuisance trees to return the forest to a more natural condition. Once those trees have been removed, excess buildups of fallen limbs and other debris on the ground are raked off the land. Then controlled fires are set to restore the land to a more natural condition, one in which fire can safely play its natural role of cleansing the forests.
Cost and controversy are the reasons thinning is not being accomplished on a larger scale, according to the method’s advocates.
There is agreement between federal land managers, scientists and most environmental groups that thinning works, and that it is desperately needed.
But the concept ge ts bogged down in disputes over what to cut, how much to cut and where to cut.
The biggest fights tend to involve tree diameter. Virtually every tree -thinning project that has been proposed by the Forest Service for the last decade that did not impose a diameter cap acceptable to environmental groups has been blocked by appeals or lawsuits, according to agency officials, appeal records and court documents.
The tree diameter that is acceptable to environmental groups changes. Some say a 16-inch cap is reasonable. Others advocate 12 inches, or nine inches, or six.
The underlying fear expressed by environmentalists in the thinning debate is that the Forest Service will use it as a mechanism to bring back large-scale commercial logging in Arizona. Large trees have commercial value. Small trees typically do not.
There is a scientific reason for diameter caps, said Brian Segee of the Center for Biological Diversity, an environmental group. Large trees in ponderosa pine forests are naturally resistant to fires, he said. It is the small trees that make up what are known as "doghair thickets" that heighten the fire danger, he said. They burn rapidly and carry the flames into the crowns of the larger trees.
Yet the Forest Service has continually tried to mix cutting large-diameter trees into what would otherwise be legitimate thinning projects to benefit commercial logging companies, Segee said.
"If you go out and cut large trees and leave behind the dog-hair thickets, that’s not going to reduce the fire danger," Segee said.
Forest Service officials agree that small trees are the main problem, and that large trees are more resistant to fire. But they say they cannot effectively treat forests to minimize fire danger with arbitrary diameter caps.
Treatments need to be dictated by what is needed on a particular patch of ground, said Tom Beddow, fire management officer for Apache-Sitgreaves. In some areas, large trees may be clustered, competing for nutrients and water so that none is healthy, he said. Such stands also have the interlocking tops that can turn into crown fires, as occurred with the Rodeo-Chediski fire, he said.
Selling marketable trees to timber companies can also offset the cost of thinning, allowing more ground to be treated, Beddow said.
"It’s a red-herring when you start putting diameter caps on forest health," Beddow said. "What we ought to be looking at is what makes the forest healthy and what’s the distribution of trees to continue with a healthy forest. The problem is we’ve got so many trees. It’s not just the little trees. It’s not just the big trees. It’s the whole age-class distribution."
Thomas Kolb, a forestry professor at Northern Arizona University, said there is no scientific basis for a diameter cap. While environmentalists frequently toss out the term "old growth" interchangeably with large trees, they are not the same thing, Kolb said. True old-growth ponderosa pines, generally those more than 120 years old, have distinct characteristics such as yellowing of the bark, he said. Big trees are not necessarily old trees, he said.
"It’s distressing that so much energy is placed on that discussion because it’s almost a trivial issue from my perspective," Kolb said.
Taylor McKinnon of the Grand Canyon Trust, an environmental group that has worked closely with the Forest Service to develop large-scale treatment projects in the Flagstaff area, concedes diameter caps are not a scientific standard. But if the Forest Service would agree to reasonable limits, there would be fewer delays from appeals and litigation, meaning most of the work that is needed could get done on the ground, he said.
"Opponents of a diameter cap will say there is no scientific rationale for it," said McKinnon, whose group generally supports limits on cutting that protect trees larger than 16 inches. "I would turn that around and say there is no scientific rationale for not having one."
There also are disputes about where to thin. Most environmentalists argue that efforts to clear out overgrown forests should be concentrated within a few hundred feet of communities to create a defensible space if a fire occurs.
Sandy Bahr, conservation director for the Grand Canyon Chapter of the Sierra Club, said that with so much to do and limited amounts of money to spend, it makes more sense to concentrate efforts in populated areas rather than trying to thin deeper in the forests.
"There is no reason to go into the back country because nobody’s going to be able to guess where the next fire is going to start," Bahr said.
Critics of that approach say it amounts to writing off overall forest health. They point to the Rodeo-Chediski fire as an example in which creating defensible spaces only around communities would have little effect. The fire started deep in the wilderness and exploded long before it reached populated areas.
Treating small patches near communities will not eliminate the danger of deadly wildfires, Covington said. Only treating around communities also does nothing to address the larger issue of deteriorating forest health, he said.
"Simply installing fuel breaks around our cities and rural developments, and forsaking the wildlands, would be an abdication of our responsibility to future generations," Covington said.
McKinnon said the Grand Canyon Trust has split from most of the other environmentalists on the issue of whether thinning should be confined to urban areas. Protecting communities while leaving the forest to deteriorate further makes no sense, he said.
"All of the things we are about — protecting and restoring ecosystems and the biodiversity they harbor - depend on those forests not burning up," he said.