The Santa Ana wind, which hits Southern California like a parched hurricane almost every fall, followed an unusually dry winter and spring this year. The California summer was, as usual, hot and rainless. An autumn with dry earth, dry trees, dry grass—all it took was a spark.
The sour though sensible aftereffect of the Malibu and San Diego County fires is that California homeowners are beginning to look at their trees and plants not as beloved and beautiful green stuff but as fuel for a future fire.
The lingering edginess and increased sensitivity to this threat is a lot like the way Californians feel about earthquakes. It would be nice to put the wineglasses up there on a shelf over the sink, but in a quake those glasses would be dangerous missiles. Similarly, it would be lovely to have that oak tree at the corner of the house shading the deck, but fire could race up the tree trunk to the roof. Now, in fact, wooden decks are strongly discouraged, and should be replaced by stone or cement patios. A rose-covered cottage is now perceived as a firetrap.
When your biggest investment is a house in fire country, every green thing that could turn brown starts to look like "flammable material," in the terminology of firefighters. Indeed, a relatively new law requires Californians to remove dead, brown flammable material and to severely thin out even potentially flammable green material. Property owners must maintain a lean, clean relatively bare zone in an area of 30 feet immediately surrounding a house, plus a "reduced fuel zone" in the remaining 70 feet or to the property line.
It's quite a precedent. On the positive side, the clear space makes the house less likely to ignite, though in a high wind all bets are off. The bare area makes defending a home less dangerous for firefighters. But this cleanup also means no more picturesque tall grasses; no more woody trumpet vine or wisteria winding up the front porch pillar; no more paths carpeted with pine needles or wood chips; no groves or tall hedges, since under the law, trees must be at least 10 feet apart, 30 feet apart on a slope.
Home gardeners are advised to space shrubs as well as trees far apart to prevent fire from jumping from bush to bush. A disconcerting passage on this topic from one University of California advisory (PDF) reads, "The actual between-plant spacing depends on one's aversion to the risk of fire spreading to one's home, and the associated chance of losing it." We presume that all those property owners not averse to collecting insurance (and not worrying about losing the photo albums, CD collection, and the family cat) can go ahead and put their azaleas in close formation.
The California Department of Forestry and Fire Protection Web site features a folk song—no kidding—about cleaning up your yard, and a scary movie ("Without 100 feet of defensible space, this house never had a chance.")
Some Southern Californians, eager to protect their real estate, have already complied with excessive enthusiasm, clearing their plots down to bare earth. This produces not only a very dreary yard but also a yard vulnerable to erosion, exposing the house to yet another California disaster—mud slides. (Plants shorter than 18 inches are allowed near the house. Well-watered flowers and succulent plants are recommended.) But bare earth doesn't stay bare; weedy annual grasses sprout fast, and when they die back, they're exceedingly flammable.
Beyond the idea of succulent plants—things like sedums and cacti that store water in their thick fleshy tissues—experts don't agree on what plants would be especially helpful. There is agreement (PDF) on what trees to avoid—junipers, pine trees, eucalyptus, and Italian cypress. Unhappily, pine trees and cypresses happen to be the particular favorites of the owners of Mediterranean-style luxury homes. (Here's more information on what not to plant and a map of which areas are at greatest risk.)
Of course any tree or plant will burn if the fire is strong enough, but well-watered plants do burn more slowly. So the advice is to keep your plants watered, get rid of debris, and lop off dead branches. All these steps are certainly reasonable (assuming there will be water for irrigation), but they underestimate the power of wind-driven smoldering wood. In November's Malibu fire, embers were flying horizontally in a 60-mph wind. With conditions like that, you could put a moat around your house and it would still catch fire.
The soon-to-be-mandatory vegetation whacking applies to what's in the homeowner's garden. But for years there has been a movement to have fire prevention extend farther into the wild, specifically to cut wide fire breaks through the native chaparral or initiate controlled burns of that native vegetation.
These are not great ideas. Like the bare yard space, the bare ground would sprout weedy grasses. And much would be lost. The chaparral plants, aside from being habitat for a lot of creatures, have deep roots that hold hillsides and cliffs in place, a useful trait in earthquake country. The plants catch the moisture of the winter rains and evaporate it back through their leaves into the atmosphere, beneficial in wildfire territory.
When you fly from San Francisco to San Diego, the olive-green velvet you see on the thinly populated hills below is chaparral. It's a dense, complex interweaving of low trees, shrubs, and plants, including scrub oak, ceanothus, manzanita, and sage. (The word chaparral is derived from a Basque word for a thicket of dwarf oaks.)
The same sort of mixture of vegetation, adapted to hot, dry summers and mild, rainy winters, grows in the south of France and is known as the maquis, a word with heroic connotations. The French resistance to the Nazi occupation was known as Le Maquis, from the phrase "prendre le maquis," to take to the hills.
One of the late Ronald Reagan's great pleasures when he took to the hills at his ranch above Santa Barbara was to attack the California maquis with a chain saw. Under the new state law, homeowners must be out there emulating the late president, or pay a $500 fine.
What makes that green velvet frightening to some is that many of the chaparral plants are combustible—it's the way they evolved to keep their species going in a fire-prone environment. For some of the plants, the strategy for weathering the dry summers is to become resinous, thus flammable, and to sprout back from the surviving crown within weeks after a fire. Others have seeds that actually require fire to germinate—either the heat causes the seed coat to split or the nitrogen dioxide in smoke sets off a reaction that causes the seed to crack and put out a green seedling the first time it rains.
Patches of the chaparral burned and renewed themselves for centuries. No one cared much until 40 or 50 years ago, when cities expanded. We've become frighteningly house-centric in our vision of how to manage the land.
One of the continuing and fascinating problems for all gardeners is how to learn to live with the power of natural forces. The chaparral plants adapted to live with drought and fire. Spacing out the trees and getting rid of dead wood seems for now to be our adaptation to the same fire-prone climate. Still, something will be lost if Southern California's hillsides turn into a mosaic of fire-retardant fortresses, with a landscape of isolated trees, stone terraces, and little flower beds mulched with colored pebbles rather than wood chips. These gardens will not blend gracefully into the natural surroundings. Homeowners may look up from their chain saw work and think, the groves of native oaks, the masses of blue-flowered ceanothus, the sage-scented air—weren't these a big part of why we wanted to live here?