Sunday, 10 August 2003

GUEST OPINION

Living with fire

We can either have regular, planned, low-severity surface fires and smoke, or irregular, unplanned crown fires and smoke.

Without controlled burns, the Catalinas will face another catastrophe

By Thomas W. Swetnam

SPECIAL TO THE ARIZONA DAILY STAR

The Aspen Fire was the "big one" that residents of Summerhaven have worried about for many years. Last year's Bullock Fire was just the preview. Now, amid the ashes and ruins on the mountaintop, residents, forest managers, and county officials are all considering how the rebuilding and restoration should take place. New zoning and building codes are in the works.

Most people recognize that this is an opportunity to do the right thing for mountain residents and visitors, and for the mountain itself. Although we have heard much in recent days about the need for new buildings to be "fire-wise" and to have "defensible space" as protection from future fires, there has been little public discussion on what to do about the larger landscape that encompasses Summerhaven.

The Santa Catalina Mountains, like most of our pine and fir covered "sky islands" in Southern Arizona, were often visited by fire over the centuries before Euro-American settlement. Lightning and American Indians frequently set fires on the mountain. Tree-ring studies carried out at our University of Arizona laboratory indicate that burns the size of the Aspen Fire probably occurred once every 20 or 30 years, and smaller fires occurred within parts of the Catalinas as frequently as two or three times per decade. These frequent fires were generally of low severity; they burned along the forest floor with flame lengths of one to several feet in height. The surface fires maintained pine forests as open parks, with little fuel accumulation in the understory.

The first fire to be fought in the Santa Catalinas occurred in May 1900. A handful of government surveyors just happened to be on the mountain examining the timber and range resources for a new forest preserve. They stopped the fire with makeshift shovels and cut-off tree saplings used as flame beaters. Effective fire fighting by the Forest Service throughout the 20th century assured that this was the last fire larger than 10,000 acres to occur in the Santa Catalinas until the Bullock Fire last year. The lack of frequent surface fires led to heavy fuel accumulations and closed-canopy forests. Combined with drought and wind, these forest conditions led to the unusually severe fire behavior of the Bullock and Aspen fires. The contrast couldn't be greater between then and now: in 1900 a few firefighters used tree saplings to beat down surface flames; in 2002 and 2003 dozens of elite hotshot crews and huge helicopter tankers struggled in vain against walls of flame roaring up slopes and ridges.

So now what? The "big one" has occurred, so can't we just rebuild fire-wise structures in Summerhaven and all will be well? The blunt answer is: "No." There is still considerable danger of future conflagrations in the Catalinas. In fact, the danger may even be heightened in coming years in certain areas on the mountain. Consider that the Bullock and Aspen fires burned with high severity over about 30 to 40 percent of the total area within the perimeters of the burns. "High severity" means that the canopies were completely burned or killed by what is called "crown fire." Over the rest of the area, 60 to 70 percent burned either as low to moderate severity surface fire, or it did not burn at all. So this means that most of the forested area on the mountain still has considerable fuel accumulation, and many of these areas will probably burn severely in the future if we do not act.

If you doubt that the danger still exists, I suggest that you take a walk out onto Sykes Knob off the Catalina Highway, and take a look west and north up Marshall Gulch toward Summerhaven. Yes, the slopes and forests above Summerhaven are toasted, and won't be a major fire hazard for some years to come - but the gulch itself is still crowded with living and dead trees that will provide ample fuel for another fire run toward the heart of Summerhaven during a future drought and wind event. The same goes for the Rose Canyon and Palisades areas, where the housing developments were mostly spared - this time.

In some ways the mosaic of burned and unburned forests is good news for the mountain - but only if we do not squander the opportunity provided by the Bullock and Aspen fires. Now is the time to think strategically and boldly about our stewardship responsibilities for the whole mountain, not just the rebuilding of homes and businesses. The areas of the mountain that had surface fires of low to moderate severity during the Bullock and Aspen fires will need further treatments if we are to avoid losing buildings, valued watersheds and wildlife habitats in the future.

From experience elsewhere in the Southwest, the first surface burns in pine and fir forests after more than 100 years of fire exclusion usually accomplish considerable reduction of dead fuels (i.e., grasses, shrubs, branches, logs, etc.) on the forest floor, killing off many small-diameter trees, and the raising of canopy levels above the surface. The killed trees and scorched foliage, however, will soon fall to the forest floor, and so the amount of dead fuels will soon rise back to high levels. If we don't follow up with prescribed surface burns within a few years, the fuel levels will be just as dangerous in some areas as they were before, if not more so. It will take several burns at intervals of about 5 to 15 years before dead fuels are decreased, forest canopies are opened up, and a safer and more sustainable forest is restored. Repeated burning at decade or so intervals will then be needed to maintain healthy, pine-dominated forests.

We need to begin planning for landscape-scale forest thinning and prescribed burning in the Santa Catalinas, including the Oracle area. Chainsaw work should be focused around homes and communities to achieve defensible spaces. Paying for this work, deciding what gets cut, and disposing of the thinned trees will be difficult - but all of this will actually be the easy part. The hard but essential part will be implementing and sustaining a long-term program of prescribed burning over the rest of the mountain. This will entail using surface fires to burn over very large areas. Thousands of acres will need to be burned during seasons and years when it is safe to do so. The opportunity for beginning this large, landscape-scale effort will never be better. In the low- and moderate-severity burned areas, the Bullock and Aspen fires have begun the forest restoration process by consuming some of the accumulated fuels. Fire-control lines are in place and could be maintained, and the high-severity burn patches will provide fuel breaks in the short term.

Implementing a landscape-scale restoration effort in the Catalinas will be especially hard because there will be risks involved, and there will be plenty of smoke. The risks of "escaped" prescribed fires are always present (recall the Cerro Grande Fire and Los Alamos disaster of 2000), but these risks can be minimized when managers are well-trained and the urban areas at risk are well-prepared.

The residents of the Santa Catalinas, Oracle and Tucson need to ask themselves this hard question: Are you willing to accept, but also to help minimize, the risks of prescribed fire, and to tolerate the smoke? If not, then I believe the consequences will be more Bullock and Aspen fires, and continued loss of our watershed and habitat resources on the mountain. We can either have regular, planned, low-severity surface fires and smoke, or irregular, unplanned crown fires and smoke.

We all understand that there are many reasons why such a mountain range-scale effort may not work. The costs, the risks, and the smoke are all daunting. But there are hopeful examples out there to look to for inspiration. The closest at hand is the Rincon Mountains. Since the 1970s Saguaro National Park has had a landscape-scale "natural" and "fire use" program. Parts of the top of Mica Mountain have been burned by surface fires as many as four times since the 1970s - and the forests show it. Simply put, most of the forests on this mountain are not only open and beautiful park lands, but they are also more resilient to fires than almost any other large forested area in the Southwest.

Can people coexist with fire? That is the most difficult question. One last example suggests that it is possible, if people are willing: Until the 1940s and '50s rural people in the Southeast coastal states lived within and near millions of acres of southern pine forests that burned almost every year. Woods' burning was a way of life, and it was widely recognized as essential and healthy for the forests. The Apache people of the Southwest also knew this fact of forest life. If we want to keep our forests and watersheds, while also living within them, we must learn to live with fire, too.

* Thomas W. Swetnam is professor of dendrochronology and watershed management and Director of the Laboratory of Tree-Ring Research, University of Arizona. He currently serves on Gov. Janet Napolitano's Forest Health Advisory Council.