What the Science Says
Vegetation isn’t the enemy - removing moisture is.
“...the plants are definitely not relevant once it gets into the urban environment, because the primary fuels are the homes.”
Wildfire policies throughout the nation are based on a simple idea: eliminate vegetation to reduce home ignition during fires. But recent research led by fire ecologists challenges this outdated fire defense—and call for a science-based path forward.
When fire management policies commonly used in forests—such as vegetation clearing—are applied to urban landscapes, the results are destructive to the ecosystem and can actually increase fire.
Urban Fires Are Different from Wildfires
Traditional fire science focuses on wildland fires driven by vegetation. But today’s fires in dense places like Altadena and Pacific Palisades behave differently: homes ignite from embers, flames, and heat from other buildings not from plants.
Space Between Homes Matters Most
Many homes in dense cities like Los Angeles are 5 feet apart or closer. Buildings often ignite other buildings, and embers move horizontally from house to house. Here the structures are the fire’s fuel and it is the houses that ignite the plants — not the plants igniting the house.
Moist Green Plants Improve Structure Survival
Shaded, hydrated gardens offer more protection than sterile, bare yards, or gravelscapes, and plants with low moisture content. Bare ground, dry vegetation, and low tree moisture were associated with greater building loss. Many homes ignite despite having gravel or artificial turf near the home.