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American Society of Landscape Architects


March 2004 Issue

Crying "Fire!" in a Crowded Landscape
Do Firewise initiatives ward off—or help spark—catastrophic wildfires?
By Kim Sorvig

Crying Paul Grupp Photo

"I’ve never seen the sunrise so bright," ASLA’s past president Dennis Otsuji recalls his wife saying. "It’s bright orange to the east."

The date was October 26, 2003, and what they were seeing was the glow of the Cedar Fire, 10 miles from their San Diego home of 18 years. One of seven wildfires that scorched 600,000 acres from Los Angeles to the Mexican border in a week, the Cedar Fire ultimately destroyed nearly 1,500 homes and killed 15 people.

"It was smoky," Otsuji, FASLA, remembers, "and I said, ‘uh-oh, another fire.’ An hour later they were telling us to get out."

The Otsujis’ property is located in a quiet suburb near Poway, on San Diego’s hilly northeast side, which is punctuated with small canyons where chaparral and eucalyptus thrive. Grabbing their pets and a few possessions, the Otsujis fled down the main road south.

"As soon as we started, the roads were jam-packed. We were just basically parked trying to get out of there," Otsuji says. On their heels came 100-foot-high flames, rushing before the Santa Ana winds. Otsuji figures that a slight change in the wind direction is the only thing that saved him and many of his neighbors from a fiery death.

Shortly after the evacuees escaped, the winds changed again. The fire swept up the valley, devouring long-neglected understory beneath the eucalyptus and sometimes jumping into the canopies. When the fire reached the Otsujis’, the house burned so fast and hot that nails from the wood deck dropped to the sooty ground in perfect rows.Blue-glazed planting pots shattered symmetrically, leaving cylinders of baked soil holding small singed palms. Structural concrete spalled in the heat. Aluminum was reduced to unidentifiable puddles, yet a plastic trash barrel survived, its warped and bubbled side still bearing the legible inscription "City of San Diego."

Bob Younger woke at one in the morning, smelling smoke. His wife Sandra, a consultant to San Diego landscape architects Deneen Powell Atelier (DPA), slept on. Bob called the nearest fire station, three miles away, and was told that the fire was moving in a direction that didn’t threaten their house. Two hours later, he and Sandra woke again to see fire coming across the far side of Wildcat Canyon, which their house overlooks. "We thought, ‘ok, it’s the other side, we’ve got a little time,’" Bob says. "Literally seconds later we saw it right here."

Wildcat Canyon is textbook "Urban Wildland Interface," the term firefighters use for areas where residences spread into rugged wooded landscapes. The steep hills are covered with a mix of chaparral and coastal sage—two fire-adapted vegetation communities—and oak groves are in the stream bottoms. It has views clear to Mexico and was exactly where the Youngers wanted to live. "It put our hearts at rest," says Sandra.

If any home should have been fire safe, it was the Youngers’. The contractor took every fire precaution with the house, and the Youngers had spent $10,000 on officially recommended landscape measures just a month before the fire. "This house was built with all the fire-safe things in mind—stucco outside, flush windows, sealed soffits," notes DPA’s Jon Powell, ASLA, a close friend. "Below the house was pretty much cleared, all the correct stuff, low plants, no touching canopies, trimming in between, all that." In addition, the Youngers had a second firebreak created farther from the house and added a 10,000-gallon water tank with gravity-feed sprinklers. "Even though the power went out," says Bob, "it dumped all that water into this house, but it didn’t make a lot of difference."

The Santa Anas were gusting to 70 miles per hour in Wildcat Canyon that night. The fire blew out the windows, in some places without touching nearby vegetation. "Once the fire’s inside, there’s really nothing you can do," notes Bob Younger. "The kitchen had granite countertops, and you could crumble the granite in your hands." Based on that and a melted porcelain tub, insurance experts estimated temperatures at nearly 5,000 degrees.

Twelve of the fifteen people who died in the San Diego fires perished within a mile of the Youngers, who were the last people to get out of Wildcat Canyon alive. "Considering the intensity of the fire and how quickly it moved, it’s remarkable more people didn’t die," says Sandra. She and Bob, with their dogs and Bob’s wildlife photographs, drove through fire and smoke "so thick we literally couldn’t see anything," she recalls. "I couldn’t see the road. This bobcat jumped out of the bushes, running from the fire, right in front of our car. I could see him just enough to know he was running down the road, and I followed him. That’s how I knew where the road was."

What is unusual about these two stories, beyond personal tragedy and courage, is what they say about landscape ordinances that promise fire safety through vegetation removal. If those promises were reliable, neither the Youngers’ nor the Otsujis’ house would have burned.

With 33 years of landscape practice in San Diego, Dennis Otsuji is no newcomer to this naturally fire-prone region. Newcomers, clueless about regional conditions, are often faulted (sometimes justly so) for being in denial about fire issues and for refusing to clear their landscapes. Otsuji, an advocate of regionally adapted design, knows the issues well enough to have helped revise fire codes that he calls haphazard. He and his neighbors had taken steps to protect their houses and landscapes.

"I thought I knew our weak points," says Otsuji, "and changed them. But on our street it was hit or miss. My neighbor above, the fire went all the way to his fence, burned all the eucalyptus trees, singed all his plant materials against his house, didn’t burn his trellis, which is wood." But in almost identical conditions at the Otsujis’, when the fire rushed up a vegetated cut slope to their property line and a wood deck, it didn’t stop. "It followed the manufactured slope on our side, came in the yard, caught the house on fire, and that was it. And then it skipped two houses and got one more."

Otsuji had designed and built the garden himself. It should have met most of the guidelines advocated by "Firewise" groups, whose federally funded publicity places extreme emphasis on "defensible" (cleared) landscapes. Japanese influenced in style, the garden contained primarily ground cover and small trees, their canopies not touching, and it was subdivided by water features, pavement, and the courtyard-based design of the house itself. "Things we did," Otsuji notes, referring to the whole neighborhood’s efforts, "stopped the fire in certain situations but not others."

If a seasoned landscape architect, well versed in local conditions, can’t guarantee the safety of his home by following landscaping codes, how can those codes help homeowners with less expertise, or people who are in complete denial about the dangers of fire?

The Youngers may not have Otsuji’s depth of personal experience in landscape management, but they made sure to comply with the best official advice they could get. Following the letter of Firewise regulations did nothing to protect the Youngers or their neighbors. None of the houses on the Youngers’ hill survived, although all were built similarly for fire resistance. On the far side of Wildcat Canyon, though, two houses stand surrounded by uncleared and unburnt greenery. A small fire burned there three years ago, and was contained by firefighters. "What burned then didn’t burn now," notes Bob Younger. As Powell puts it, smaller local fires prevent the catastrophic ones. Precautions like the Youngers took could withstand such lower-intensity fires, but as fires burn ever hotter, says Powell, there’s no defending against them.

When cleared "defensible space" fails to defend homes where recommended precautions have been taken, something is wrong. At the least, Firewise clearing puts an official stamp on a false sense of security. At worst, clearing appears to contribute to regional conditions that are making intense wildfires more frequent and more volatile.

What is happening when fire-prevention recommendations, produced by experts, often enforced by law, and followed conscientiously by the Otsujis, the Youngers, and probably countless others, fail to deliver the promised protection?

This question can only be understood by analyzing whole landscapes and multiple issues, an approach landscape architects need to bring to this critical policy debate. What are the unintended consequences of fire-prevention policies in fire-prone ecosystems?

"There are so many factors involved in fire behavior," says one disgusted firefighter who wishes to remain anonymous, "that to advocate using one single factor for control is misinformation of the lowest sort." Yet Firewise codes, publicized at immense taxpayer expense, hammer away at a single issue—landscape clearance, a.k.a. "fuel modification" and "defensible space." Although some codes also advocate resistant building materials, improved access roads, and even zoning restrictions, the first message to the public is always, as Otsuji puts it, "Mow down all the trees."

Mission Trails Regional Park, a 4,500-acre open space a few miles south of Otsuji’s house, illustrates the complex roles that landscapes play in fire zones—roles not always well recognized even when they save property and lives.

Ranger Sue Pelley has fought wildfires alongside volunteer and professional firefighters, but today she concentrates on Mission Trails’ role in public environmental education. When the recent fires roared through the chaparral and coastal sage of the park’s northwestern half, she says, "it was almost ideal as far as the kind of fire we’d like to see"—that is, one that will clear out growth. The chaparral, with its typical mix of resinous plants like Ceanothus (many species of "California lilac"), burns hot enough to expose bare mineral soil, required to germinate many fire-adapted species. In coastal sage areas, the fires burn less intensely, removing grasses. Even before Firewise regulations, residential clearing had destroyed some 90 percent of coastal sage communities, once dominant across southern California.

The park landscape stopped the fire, sparing not only Mission Trails’ multimillion-dollar visitor center but also neighborhoods beyond the park. "It just stopped at the San Diego River," says Pelley, "running out of fuel and reaching moist ground. Time of day and temperature played a big part as well." In San Diego, like most urban areas, many of the stream courses that once acted as natural firebreaks have been paved over. Other valleys have become open space and may actually conduct fire into neighborhoods due to lack of maintenance. In the case of Mission Trails, the natural conditions conserved in the park protected adjacent neighborhoods.

Not all the neighbors recognize their debt to the park’s native vegetation. One neighborhood, outraged by the loss of several homes, "didn’t want anything to be allowed to grow back in Mission Trails. They just wanted iceplant (a hard-to-burn succulent ground cover) planted everywhere."

Pelley understands the fear and frustration that drive such demands, but blaming vegetation for doing what it is adapted to do is no solution. "The idea we have to erase," she notes, "is that we can prevent forest fires. Smokey the Bear has been telling a story for a long time, and that’s not really the story we need to tell."

The story people need to hear is specific to region and ecosystem. Current wildfire research is displacing conventional wisdom based on "short periods of study and not enough information," Pelley says, but even so, there is too much one-size-fits-all theorizing. For example, here in the chaparral, she says, "a lot of fire management practices are being based on data from pine habitat, which is completely different." She cites California biologist Richard Halsey’s research showing that while historical fire suppression in pine forests has made stands denser and crown fires more frequent, wind-driven chaparral fires have been a constant over the past 500 years.

Regulations based on canopy conifer forests aim to eliminate underbrush and leave thick-trunked, well-spaced trees. These concepts don’t deal with the reality of chaparral, which can be crudely called "all brush and no trees," with high winds fanning flames to enormous lengths. Both Pelley and Otsuji note that San Diego County’s clearance requirements—from 30 to 100 feet—are inconsistent, while Powell expresses dismay that "the fire department is becoming the single overriding force in urban design." Echoing the Youngers’ experience, Pelley says, "I think massive clearing is altogether foolish because nothing’s going to protect your structure if the wind’s blowing."

Southern California has enforced landscape-clearing regulations for years (see "Design Under Fire," Landscape Architecture, December 2000). Yet even Ventura County, which guarantees compliance by clearing reluctant owners’ properties for them, had two vast fires this year. There, even some of the most cleared landscapes imaginable—agricultural ones—burned: vineyards, orange groves, even boxed ornamental nursery stock.

Simplistic dogma about clearing still abounds. Near the barely spared town of Julian, 40 miles east of San Diego, just beyond an utterly charred state park, the California Department of Forestry still displays a typical sign. "Reduce your risk of wildfire," it exhorts passersby. "Clear 30–100 feet away. Make it safe to stay."

"What they really need to look at is policy change and building material changes," says Pelley. But zoning changes would provoke lawsuits, and fireproof construction costs both homeowners and developers. Far easier to get people to enlarge lawn- and shrubscapes and let them think this makes it "safe to stay."

A false sense of security may be the least of the damage done by fire-prevention clearance. There is growing evidence that clearing actively contributes to conditions that are making fires more intense, frequent, and uncontrollable across the United States and the world.

"If someone told these homeowners," one landscape architect mused, "that a logging company was about to remove 50 to 80 percent of the vegetation around their home, they’d scream bloody murder." Yet that is the average required by Firewise regulations for distances that add up to astonishing acreages (see "Doing the Math").

The effects of removing significant percentages of existing vegetation from an area are well-known. Organic matter that would normally fall as leaf litter and compost into the soil is removed. This decreases the soil’s capacity to retain water and make it available to plants, and it also lessens the soil’s structural stability. Removing vegetative cover, which normally holds soil in place, leads directly to soil erosion, which removes yet more organic soil in a vicious cycle. Runoff also increases so that less precipitation stays around long enough to infiltrate the soil. With canopy shade removed, the soil bakes and crumbles, eroding more easily. Soil temperatures rise, as well as localized air temperatures. Last but far from least, the cleared vegetation no longer absorbs CO2; the loss of CO2 "sinks" is being urgently monitored as a leading cause of global warming.

Warming and drought, in fact, are the common threads through all the effects of clearing. Drought is what is really driving wildfire today; the California Department of Forestry’s own pamphlets state this flatly, and hardly anyone disagrees. Parched soil with dry, stressed, and dead plants provides ideal conditions for fire. Relatively small increases in air temperature can transform a calm burn into an inferno. The same temperature changes, linked to global warming, are believed to be responsible for gustier winds and sudden fluctuations in weather—both of which make fire harder to fight. Clearing on the scale demanded by Firewise regulations contributes to each of these dangers.

Scientists are only beginning to quantify the relationships among clearing, drought, and fire, but that is no excuse for ignoring the likelihood that clearing to prevent fire is like damming rivers to prevent floods. Processes like flooding and fire are inevitable, and even though a "prevention" strategy may work in some cases, it can actually worsen the problem.

Although the political and social issues of wildfire are immense, landscape architects have a contribution to make. Without a whole-landscape view of fire, drought-driven conflagrations will continue to intensify, and accepted "safety" measures will become increasingly ineffectual (see "Alternatives,"). "This might be the right time for the national ASLA to put a task force together," says Otsuji, calmly thinking ahead beyond his personal losses. Along with landscape ecologists and planners, our profession might just have the beginnings of answers that work better than "clear away, safe to stay."

A resident of Santa Fe, Kim Sorvig won the 2002 Bradford Williams Medal for landscape writing.

(These resources were originally listed at the end of the article "Will Wildfire Ravage Our Profession?" Landscape Architecture, December 2001, and have been modified for this article.)


  • Colorado Plateau & Land Use History of North America Project posts many good papers at A subpage—/Biota/wildfire.htm—is specific to fire-adapted forest ecology.
  • "Effects of Fire Suppression on Ecosystems and Diversity," by John D. Stuart, and many related articles can be found at
  • "Forest Restoration in Southwestern Ponderosa Pine," Dennis Lynch et al., in Journal of Forestry, August 2000.
  • In Fire’s Way: A Practical Guide to Living in the Wildfire Danger Zone, by Thomas Wolf; University of New Mexico Press, 2003.
  • Mapping Wildfire Hazards and Risks, edited by R. Neil Sampson et al.; Food Products Press, 2000.
  • Stephen J. Pyne’s books on fire history: America’s Fires: Management on Wildlands and Forests, 1997; Fire in America: A Cultural History of Wildland and Rural Fire, 1997; Introduction to Wildland Fire, 1996; Wildfire: A Reader, 2001; World Fire: The Culture of Fire on Earth, 1997.
  • Wildland-Urban Fire Research publications can be found at
  • Yellowstone and the Fires of Change, by George Wuerthner; Dream Garden Press, 1989.

Conventional Fire-Protection Organizations:
(These groups tend to favor aggressive vegetation removal.)

Doing the Math

Official policy ignores the concern that clearing vegetation may actually increase fire-prone drought conditions. "Firewise" clearing (taxpayer-funded vegetation removal initiatives) is rapidly expanding to affect millions of acres. The seriousness of this issue becomes clear when you look at some rough calculations.

To examine how a simple rule like the "100 foot clear zone" can affect a region, let’s consider a hypothetical region (size, population, and policies similar to Ventura County): San Combustíble County (SCC), California, has 1,180,800 acres (about 1,845 square miles) and is home to 753,200 people in 243,234 households.

Every year, the scc fire department requires 15,000 households to clear vegetation 100 feet around each residence. The average house is 2,500 square feet, and the clear zone is 60,000 square feet. It is also required that 10 feet on either side of a driveway be cleared. The average rural scc driveway is 1/4 mile. Cleared edges are 26,400 square feet. The total clearance is 86,400 square feet, or 2 acres (not including house footprint or driveway surface).

The total for 15,000 houses: 29,752 acres, or 46.49 square miles, cleared annually, increasing with new development. (At this rate, the state of California would clear 2.5 million extra acres per year.) The annual fire clearance is 2.5 percent of the county. But—here’s the rub— scc, like many parts of the United States, has only 10 to 15 percent not already cleared, of which fire clearance affects 25 percent.

In scc, an acre of forest/scrub produces 2.67 tons dry weight of vegetation per year (the green weight is at least double that). San Combustíble regulations (like those in many real counties) define clearing as removal of 50 to 80 percent of vegetation. On nearly 30,000 acres cleared for fire "prevention," these percentages remove 15 to 24,000 tons. (scc’s dump charges only $5 per ton, totaling nearly $100,000. Even if chipped, the greenwaste covers an acre and is 5 feet deep.)

scc calculates stormwater using the familiar Runoff Coefficient "C" based on surface cover. For cleared cultivated land, C is about .2 higher (meaning 20 percent more runoff) than the average for a mix of woods and grassland.

Like much of nonmountainous southern California, San Combustíble County gets 10 to 15 inches of precipitation in a normal year. Usually about half of that evaporates. An increase in runoff of 20 percent means the loss of about 3 inches of that precipitation. Removing greenwaste from soil decreases the soil’s water retention, compounding runoff losses.

Removing canopy decreases shade and creates heat islands that are 3 to 8 degrees (Fahrenheit) hotter than surroundings. Even a one-degree rise dries soil and fuels more quickly and can change fire behavior significantly.

Although actual figures would depend on detailed soil and climate measurements, San Combustíble County soils normally have 7 or 8 inches of water available annually after evaporative loss. Clearing can be guesstimated to reduce that by 3 or 4 inches. The decrease is more than 50 percent of normal availability and 25 percent of total annual precipitation. These effects spread well beyond the 30,000 acres cleared each year and obviously involve significant trends toward drought.

Ordinary clearing—for agriculture, timbering, and urbanization—is known to cause the kinds of soil and runoff problems discussed here, leading to drought, spreading deserts, and global warming. Clearing for fire prevention is no different. The policy is literally backfiring, worsening regional conditions that favor increasingly intense fires in exchange for "defensible space" that offers little reliable protection.

For landscape design & management

  • Acknowledge the climate-changing effects of human activity like clearing, and factor those effects back into models, predictions, and policies. Likewise, think critically about blaming nature alone for fires.
  • Design parks as whole-community firebreaks, rather than clearing separately around every house. Incorporate wetlands, even constructed ones, in these zones.
  • Where clearing and thinning remain necessary, ensure that organic matter returns to the soil (via controlled burning, composting, or browsing of small woody materials). This argues strongly against industrial logging as "fire prevention" and should seriously limit even local small-diameter-wood extraction without nutrient replacement.
  • Restore whole forests to decrease drought conditions, along with reforestation aimed against global warming. Note that this would require a different approach than the Bush administration’s "Healthy Forests" initiative.
  • Consider community-based controlled burns—an intriguing idea from Bob Younger and Jon Powell. Divide urban—wildland zones into fire management associations, with a scheduled patchwork of controlled burns. Residents, under fire department supervision, could provide a workforce for intensive management of low-intensity preventive fires.

For construction

  • Provide exterior sprinkler systems, triggered by advancing flames or flying firebrands, functional during power outages, with heat-resistant hoses/pipes. Sprinklers wet surfaces to slow ignition, but they cannot put out a roaring fire ("You’re lucky," says one firefighter, "to put out a structure fire with 30,000 gallons").
  • Require resistant exterior materials and design details, which are more effective and less environmentally costly than widespread clearing.

For zoning and policy

  • Recognize the role of vehicles as fire starters. According to California Department of Forestry statistics from 1996 to 2000, nearly 41 percent of all wildfires were caused by vehicles and machinery. Require developments in fire-prone areas to rely on shared transportation and to design transit systems with evacuation in mind.
  • Forbid development without fail-safe access routes. Most deaths in wildfires occur when firefighters and/or residents are trapped with only one way in or out. Cul-de-sac systems should not be permitted in fire-prone areas.
  • Reevaluate zoning and insurance. Even well-informed people choose to risk living in beautiful, dangerous places. This is unlikely to change. Instead, laws should require personal responsibility in return for privileges. Hold developers as well as individuals to construction standards and insurance as in earthquake and flood zones.

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