How Invasive Plants Are Fueling California’s Wildfire Crisis
Fire has always shaped the landscape in California. But today it burns hotter, more frequently, and spreads farther than ever before—a shift driven by human development, climate change, and the prevalence of invasive species, which are non-native plants that have negative effects on local ecosystems. Grasses and trees brought to California for agriculture, landscaping, or by accident, have transformed the state’s fire dynamics.
“Many non-native species can propagate fire faster than native plants,” says David Acuña, battalion chief for Cal Fire, the state’s department of forestry and fire protection. This transformation is an overlooked driver for the increasingly destructive wildfires in California and around the world.
Southern California is dominated by shrublands known as chaparral. This landscape was historically characterized by short, shrubby plants, and any native grasses were perennial, maintaining moisture and staying green for most of the year. Fires, when they occurred, were rare because lightning strikes were infrequent. When fires did ignite, they burned hot but wouldn’t spread far because the open gaps between plants acted as natural firebreaks.
The introduction of non-native grasses in the 1700s fundamentally altered this balance. Brought by European settlers, these grasses evolved alongside heavy livestock grazing and routine burning, making them highly resilient to disturbance. They outcompeted native species and filled the gaps in shrublands, creating a continuous carpet of flammable material, especially along altered areas like roadways—frequent starting points for fires.
