USA — Los Angeles. San Diego. Santa Barbara. These are some of the most recognizable locales in the United States, if not the world. The mere mention of these names evokes visions of sun-soaked beaches, warm breezes, glamorous homes, legendary traffic and the vibrant, pulsing buzz of humanity and culture.
Yet as locals know, these regions of unparalleled fame and economic importance are also united by another feature: devastating wildfires.
Southern Californias fire ecology is unlike that of anywhere else in the United States. Fire control strategies developed for mountain forests dont have the same results here. Year after year, wildfires continue to incur tremendous economic and emotional costs to homeowners and communities.
We have averaged something like 500 homes per year lost since the 1950s, says U.S. Geological Survey and UCLA fire ecologist Jon Keeley. Now despite very effective fire suppression efforts, the situation seems to have only gotten worse, so that since the year 2000 weve averaged a loss of a thousand homes per year from wildfires.
Why are southern Californias fire losses worsening? What factors drive southern Californias fire risk and fire ecology? Are there solutions that can help southern California communities manage their fire risks, while sustaining native habitats and species?
To support the many public agencies on the frontlines of fire management, USGS scientists are tackling these questions as part of the USGS Southern California Wildfire Risk Scenario Project. A new film introducing this project Living with Fire seeks to jumpstart conversations about wildfire science in southern California, and is now available on the USGS YouTube channel and for download.
A big picture approach
The goal of the fire risk scenario project is to reduce housing losses in the future and at the same time minimize wildlife habitat losses.
The weather conditions that cause these fires occur every year, thus in southern California we need to change the way we look at fires, says Keeley, who co-leads the project with Alexandra Syphard of the Conservation Biology Institute, Ross Bradstock of the University of Wollongong in Australia, and other colleagues.
Project scientists are investigating the wildfire problem from a whole-picture lens. Some studies are assessing the effectiveness of traditional fire management methods like fuel breaks or prescribed fire, including unintended consequences such as the spread of flammable nonnative grasses. Other studies are examining the role of human ignitions, especially important because more than 95 percent of all fires in southern California are caused by humans, not by natural sources such as lightning strikes.
One important project focus is why some communities burn, and others dont, and how home landscaping, home location and housing density alters the probability of home loss from wildfires. This research is leading us to reverse our thinking about wildfires, says Keeley in the film. Instead of the traditional from the wildland-in approach, research results are telling us we need to think from the house-out.
On the wildland side, USGS scientists also are trying to understand the nuanced role of wildfires in southern Californias native chaparral ecosystem. In our research, we saw that many small wildlife species had trouble recovering from landscape-scale fires for at least ten years post-fire, says USGS ecologist Robert Fisher, another project leader. That pattern hints at how catastrophic fires also have lasting impacts on our biological communities.
The project continues to publish its research findings. Highlights thus far include:
In 2011, two studies concluded that fuel break effectiveness in southern California were dependent on firefighter access.
A series of studies from 2008 to 2011 found that large San Diego wildfires caused shifts in bird, reptile and mammal species assemblages.
In 2012, a study demonstrated that housing location and housing density were determining factors in how likely a home will be damaged or lost due to wildfires.
A study published this month modeled different housing development scenarios for San Diego County lands through the year 2030, and estimated that homes built in non-contiguous, leapfrog communities would be at more risk of burning in wildfires than homes built as part of infills or contiguous expansions of existing communities.
The project has attracted the cooperation and attention of southern California natural resource managers, including the Santa Monica Mountains National Recreation Area the largest urban national park in the U.S. and home to residential communities such as Thousand Oaks.
So, its time to re-examine how we look at these problems to find out what is effective, so that dollars we put into wildfire losses actually has a benefit that we actually see a reduction in those losses in the future, says National Park Service fire ecologist Marti Witter in the film. The really important part about having rigorous scientific data to back up the recommendations that we make is because they are counter-intuitive, because they run contrary to the way work has been done for thirty years.
The project scientists continue to study the many factors that dictate wildfire impacts to southern California. Ultimately, they hope to integrate all of these wildfire factors into a decision model that can be used by local fire managers and land use planners. The model will give communities a tool to understand which combination of strategies from fuel treatments, to land use planning, to urban landscaping will have the greatest potential for managing wildfire risk in southern California.
Wildfires are an inevitable feature of southern California, but the risks wildfires pose to communities and landscapes can be managed. USGS hopes to contribute its strengths in natural hazards science and landscape ecology to provide communities with new scientific data and new strategies knowledge that may someday show us how to live with fire in southern California.