Fire Fact Forum Presents The Science of Fire

Big pod ceanothus, a key habitat plant in the chaparral, cannot regenerate from its roots after a fire but has specially adapted seeds that need heat to germinate. However, it can only grow back if there is enough time between fires for seeds to grow into mature plants and set new seeds. Frequent fires interrupt that cycle. Photos by Suzanne Guldimann

On August 22, the Las Virgenes Homeowners Federation (LVHF) and LA County Third District Supervisor Sheila Kuehl presented “Fire Fact Forum: The Science of Fire,” at the King Gillette Ranch auditorium with three of California’s most outstanding environmental scientists: Dr. John Keeley, Senior Research Scientist with U.S. Geological Survey; Dr. Stephen D. Davis, Distinguished Professor of Biology at Pepperdine University; and Seth Riley, Wildlife Branch Chief; Adjunct Associate Professor UCLA—U.S. National Parks Service—Santa Monica Mountains National Recreation Area; Department of Ecology and Evolutionary Biology.

The guest speakers presented more information than is possible to recount here, but Kim Lamorie, president of LVHF has summarized the presentations and provided resources (videos and PDFs) on the website (lvhf.org).

Dr. John Keeley said there has been a 400 percent increase in our area burns. He classifies California fires as either fuel-dominant fires or wind-driven, and explained that in Southern California, fire is a people problem not a fuel problem. 

“Woolsey, a wind-driven fire, burned through a landscape that had repeatedly burned, so fuels were not a factor. Drought is a factor,” Keeley said.  

Keeley said that fuel management efforts are not cost or time effective for these wind-driven fires because structures in wind-driven fires most commonly catch fire due to burning embers that fly in on the wind from sometimes miles away. He also noted that green trees full of water can actually shield a house from these burning embers and that oak trees, in particular, are naturally fire resilient and can block flying embers from landing on homes, while houses are dry and considered as fuel.  

Keeley agreed that vegetation removal around buildings is important, but noted that many of the homes in Paradise, California, that survived the fire were surrounded by green trees while homes with no vegetation around them burned. 

Keeley suggested a more cost-effective preventive approach that takes fire into account in the municipal zoning and planning process as described in the book, Wildfire and Americans: How to Save Lives, Property, and Your Tax Dollars by former NPS Director Roger Kennedy. 

“With 600,000 people moving to California every year,” Keeley said, “defensible space around a home is not nearly as important as the need for regional planning, coordination, and responsibility for fire-fighting and insurance to encourage more prevention-oriented, fire-safe zoning in severe fire hazard areas and wildland urban interface zones.”

Dr. Stephen D. Davis presented compelling statistics and photographs of how native plant communities are responding to climate change, which in Southern California has been mostly fire and drought. He explained that frequent fires are permanently changing the landscape by turning woodlands into shrublands and shrublands into grasslands. Unlike many native plants, non-native species go dormant and dry in the summer and become flash fuels that burn readily and encourage more fire. 

Laurel sumac has deep roots that enable this essential chaparral plant to quickly regrow and recover after a wildfire and that help hold fire-scarred hillsides together, but this critically important native plant species is facing other threats from climate change, including a fungus that attacks plants weakened by drought.

Native plant species such as ceanothus, lupine, and laurel sumac that help restore the soil after a fire are compromised as a result of drought followed by fire.

Lupine, the purple flowers that appear on hillsides and roadsides in the spring not only present the first flower show of the season, but put nitrogen directly into the ground.

Two ceanothus varieties endemic to coastal California are Green Bark (ceanothus spinosus) and Bigpod (ceanothus metacarpus), whose roots are relatively shallow, only about five feet deep, often do not survive a firestorm like the Woolsey fire. They regenerate by propelling their seeds in the plant litter where they wait until fire stimulates them to germinate.

However, said Davis, “It takes at least six to 12 years for ceanothus seedlings to mature after a fire. If grass fires, called ‘cool’ burns, follow a wildfire like Woolsey, weeds will replace them. Cool fires don’t burn weed seeds,”he said.

“Even plants that survived the fire were already showing evidence of drought impact as they became too stressed to withstand infection,” said Davis. 

An example is the laurel sumac, whose roots go deep, as much as 40 feet, and are  more protected from fire, are slope stabilizers in burned hillsides. Some plants have, however, contracted a fungal infection that even the Woolsey fire couldn’t kill. During the drought, 62 percent of original plants died, and after the fire, 50 percent of the plants are still infected. 

Dr. Seth Riley is an associate adjunct professor of ecology and evolutionary biology and expert on bobcats and mountain lions and Chief Wildlife Ecologist for Santa Monica Mountains National Recreation Area, which is part of the National Park Service.

Riley spoke about the effects of fire in Southern California on wildlife. His research focuses on the effects of urbanization on the diversity and abundance of wildlife in fragmented landscapes, including mountain lions, bobcats, and other carnivores, as well as small wildlife such as reptiles, amphibians, and birds. 

Riley explained that populations of small mammals such as rabbits and woodrats take a long time to recover, and are hardest hit in a fire. Red-legged frogs, an endangered species that was recently reintroduced in the Santa Monica Mountains populations, were wiped out by the fire and its after effects. 

“We don’t have source data on small wildlife,” Riley said, “but 80 post-fire habitat sites in the Santa Monica and Simi Mountains are being evaluated. With stream surveys, breeding amphibians will have pre- and post-fire data in the future.”

Two local mountain lions died in the Woolsey fire. P-64, was one of the most freeway-savvy mountain lions in the area with over 41 freeway crossings under his belt. He successfully escaped the fire, but when he came up against urbanization, he opted to retreat back into the just-burned open space, and ended up burning his paws and starving to death because he could not hunt.  

The large mammals who successfully escaped have not returned to the large bare burn areas and are instead crowded into small pockets where fire did not occur. Researchers are watching to see how overcrowding in further reduced and fragmented habitat will affect their population as a secondary effect of fire. 

LVHF President Kim Lamorie who organized the event, was extremely pleased with the event outcome: “It was a wildly successful evening and extremely well attended,” she wrote  in her follow-up of the event. “Response was overwhelmingly positive, ‘Fire Facts—No More Fiction!’” 

LVHF has included links to all three presentations that evening, as well as links to their professional profiles and powerpoints at lvhf.org. They also follow below.

 

For more information and to watch videos of the presentation, visit http://lvhf.org

 

Flavia Potenza
Flavia Potenza

Flavia Potenza is executive editor of the Messenger Mountain News. She is also a founding member of the 40-year old Topanga Messenger that closed its doors in 2016. She can be reached at editor@messengermountainnews.com

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