Wildfire Preparedness

Why Central and Southern California Burn

Our region is characterized by a Mediterranean climate: mild, wet winters followed by dry, hot summers. In the several months following the last rain, humidity in the region steadily drops — especially inland. These dry conditions create a perfect environment for wildfire to spread once ignited. Much of the vegetation covering our mountains and foothills is part of a unique ecosystem called chaparral, and over time, it has adapted to these climactic conditions.

Chaparral consists of hardy shrubs and other plants that can tolerate the long summers with no rain and the constant sun. Plants like chamise, ceanothus, scrub oak, manzanita, sumacs, and many other species of evergreen shrubs cover the sun-beaten slopes of the mountain ranges crisscrossing the area. These species are adapted to cope with drought and extreme sun exposure. More importantly, these species are adapted to infrequent but high-intensity fire. Utilizing special mechanisms such as resprouting from burls and roots in the soil or having seeds that only germinate when exposed to chemicals in smoke, chaparral plants are able to recover following a wildfire.

There are many misconceptions about the role of wildfire in chaparral ecosystems, and how our communities should best prepare to live amongst this fire-prone landscape. Fire here plays a different role than it does in conifer forests, and it is important to distinguish the two ecosystem types.

Natural Fire Ecology

We often hear that chaparral is “supposed to burn,” but that doesn’t tell the whole story. Before humans settled this area, we know from a variety of scientific evidence that chaparral burned on average every 30 – 150 years. Different mountains and areas burned more or less-frequently than others, but ultimately the chaparral communities of this part of California burned two to three times per century or less. This is in contrast to mixed-conifer forests in California, which historically burned one or two times every 20 years. Some plants like manzanitas have been found to be well over a century old in chaparral communities. That’s right, old growth chaparral isn’t a fantasy — but very few stands remain. In a time when there is a lot of talk about prescribed burns, fuel load reduction, forest thinning, and brush-clearing, it is easy to forget that if it weren’t for humans, wildfires would only ignite by lightning strikes. The Los Padres National Forest has one of the lowest incidences of lightning-ignited fires in the western United States — less than 3% of the wildfires in our region since 1917 were caused by lightning.

However, once wildfires start in the chaparral-covered hills around our cities, they are naturally intense and burn every part of the shrubland community. These are known as a crown fires because they burn both the understory and the canopy of the ecosystem. Crown fires here are completely normal, typically replacing entire stands of chaparral at once — and chaparral species are adapted to them. Once a wildfire blazes through an area, these shrubs immediately begin their post-fire cycle: “fire followers” quickly emerge, scrub oaks resprout from their root systems, many manzanita species resprout from underground burls, and ceanothus seeds germinate quickly in the charred soil. This is a process best left unaided as large burned areas are difficult to restore by planting shrubs and dispersing seed due to the precise timing, species composition, and conditions needed to successfully restore native species assemblages in burned areas. Of course, we like to monitor these areas in the years following a fire for invasive species such as Cape ivy, yellow starthistle, Spanish broom, and others, removing infestations when we can.

There is one major aspect of fire in our region that isn’t natural, however: increased frequency.

Fire Frequency

Some of the largest and most destructive wildfires affecting the Los Padres National Forest were started by human activity. The 1985 Wheeler Fire was started by an arsonist, the 2006 Day Fire was started by someone burning trash, the 2003 Piru Fire and the 2007 Zaca Fire both started because of sparks from machinery being used near dry vegetation, the 2009 Jesusita Fire ignited because of sparks from a weed whacker being used for unapproved trail maintenance, and the 2016 Soberanes Fire was the result of an illegal campfire. Combined, these fires burned over 600,000 acres of both private and public land and destroyed hundreds of buildings. But if they had not ignited from human activity, those fires would not have occurred.

As more people pack into our region, the chance for wildfires to ignite increases, and they are occurring far more frequently than they did centuries ago. Over 56% of the Los Padres National Forest has burned just in the last 20 years and many of those areas have burned two or three times in the last 50 years. The Los Padres has one of the most negative fire interval return departure (FRID) values of any national forest in California, meaning that fires occurring in the same area are doing so with less time between them.

Fire is occurring too frequently for many of our native chaparral species to keep up. For example, species that only grow from seed following a fire are not given a chance to mature and produce more seed if another fire occurs in the area too soon. Eventually, areas that burn too frequently for too long will undergo “type conversion” — the permanent conversion of native chaparral to nonnative weeds and grasses. These nonnative plants do not stabilize the soil or provide food and shelter to wildlife nearly as well as chaparral species. And there’s evidence that grasslands and invasive weedlands burn more quickly when wildfires do ignite, putting people and homes in their path at greater risk.

An often-recited myth is that wildfire suppression over the last century has caused an unnatural amount of vegetation to build up, increasing the likelihood of large and intense fires. This logic does not apply to chaparral and the latest science suggests that modern fires in our region are not outside of historical norms for fire size. Chaparral is naturally characterized by dense, dry shrubs. These plants may often seem dead, but are actually uniquely adapted to tolerate drought and intense sunlight. Next time you are hiking through the chaparral, take some time to look closely at the shrubs around you. Most plants have dead limbs attached to healthy, live plant parts. In our region, the myth that vegetation is too dense or that it is “decadent” or dead because of past fire suppression efforts can have real consequences on the management of ecosystems that naturally experience intense but infrequent crown fires. When chaparral wildfires do ignite, we fully support efforts to suppress them as quickly as possible.

The Wrong Approach

Many of the ideas for how to protect communities involve vegetation removal in remote areas and large-scale landscape alterations. This approach may involve activities such as prescribed fire, vegetation thinning, and fuel breaks — techniques that are often ineffective in areas dominated by chaparral and will not alter regional wildfire trends.

Prescribed fire only exacerbates the type conversion process and doesn’t necessarily reduce an area’s risk of burning later, with studies concluding that it is not a cost-effective method in chaparral. This can be easily seen by overlapping wildfire burn areas in and around the Los Padres National Forest. For example, the 2017 Thomas Fire burned most of the areas burned by 1985’s Wheeler and Ferndale Fires, areas burned by the 2003 Piru Fire and 2006 Day Fire, and canyons that burned in the 2008 Tea Fire and 2009 Jesusita Fire. The 2016 Soberanes Fire burned over half of the area burned by the 2008 Basin Complex Fire in the Monterey Ranger District. Prescribed burns in chaparral would probably have to be conducted very frequently (every five years or less) in order to be effective, and as described above, overly-frequent fire in chaparral can have serious environmental consequences.

The timing of prescribed burns is also of concern to fire scientists. Prescribed burns must be conducted during a narrow window in order to be successful due to vegetation moisture levels and weather conditions, meaning they are often done in winter or spring when many wildlife species are breeding and birds are nesting in the area. Prescribed burns during this time may heat up the moist soil to the point that seeds are damaged by the resulting steam. And there is always the risk of prescribed burns escaping and becoming full-fledged wildfires. Likewise, clearing or thinning vegetation in the backcountry would do little to stop the spread of wildfires.

There is evidence that Native Americans used prescribed fire along the central coast before Europeans settled in our region. However, scientists have determined that prescribed fire was being used to purposefully convert the dense chaparral to grasslands to allow for movement across the landscape, the creation of open hunting areas, the selection of edible herbaceous plants, and the reduction of habitat for potentially dangerous predators such as grizzlies — not to reduce the incidence of large wildfires. Many of the areas that were converted from chaparral to grassland were then maintained by European settlers once they arrived.

You can read more about the issues with prescribed fire in chaparral ecosystems here.

Fuel breaks are another method commonly employed in the Los Padres and throughout nearby public and private lands. A study in 2011 showed that in the Southern California national forests — including the Los Padres — fuel breaks often do not stop wildfires, especially when weather conditions such as strong winds are present. The 2017 Thomas Fire and other large, wind-driven wildfires in our region easily jumped fuel breaks, highways, and other land features due to embers being blown far in front of the fire’s leading edge. These wildfires tend to be the largest and most destructive, and unfortunately fuel breaks are often ineffective in slowing their movement. For example, the Thomas Fire completely jumped a network of 70 miles of fuel breaks in the national forest around Ojai and Lake Casitas, and the fire was moving too quickly for firefighters to safely access these areas.

Despite the science, remote fuel break projects are still approved throughout our national forest. These fuel breaks are often built far away from communities at risk, and they involve initially clearing most mature vegetation and favoring regrowth of nonnative grasses and weeds. A common method of establishing fuel breaks involves mastication, or the crushing of vegetation down to bare soil. This method has been shown to reduce bird numbers by 60% and can have significant implications for biodiversity. Fuel breaks can be as wide as a football field and several miles long, removing prime habitat for many plant species that are only found in small populations along ridges in our region such as the Refugio manzanita. These plant species provide food and shelter to native birds and insects that are critical for ecosystem health. The size and length of fuel breaks and their composition of nonnative plants unfortunately makes them likely conduits for invasive plant movement into new areas, further impacting native plant and wildlife habitat.

Recommended Reading

We base all of our positions on the most current and best available science. Many of the studies whose results and recommendations contributed to our understanding of fire ecology in and around the Los Padres National Forest are cited above. Check out our Fire References page for a full list of scientific journal articles, books, and other materials we recommend reading for more information on these complex and important topics.