Chaparral

In today’s fire climate, the chaparral ecosystem has been much maligned. Dense, evergreen chaparral shrubs that are adapted to long summer dry spells can support high-intensity crown fires, which often consume all above-ground plant parts. But chaparral shrub species are uniquely adapted to fire conditions—some species have seeds that germinate only in response to heat or chemicals in wood smoke, while other species have large underground root systems that aid in resprouting following a burn. Intense but infrequent, chaparral fires have always been a natural part of the landscape.

Fascinating Features

  • Chaparral habitat occurs from about 300 to 3,000 feet in elevation and is found throughout much of California, occupying approximately 6 percent of the state’s land.
  • Fire intervals in chaparral habitat were historically between 30 and 50 years, and fires were primarily started by lightning. With increased fire frequency—which is often a result of human activity—young plants burn before they can produce seeds, sometimes resulting in habitat conversion from native chaparral to non-native grassland.

Habitat Values

Chaparral habitat is characterized by dense stands of drought-tolerant, woody shrubs that are adapted to California’s Mediterranean-type climate (hot, dry summers and cool, wet winters) by having thick, leathery, or wax-coated leaves that reduce evaporation.  Although chaparral species are adapted to drought, severe or extended periods of drought can cause increased mortality or shifts in species composition.  Extreme drought conditions can also increase the risk of fire and impair recovery after a fire.

Critical roles

Although chaparral is highly susceptible to fire—especially in the Wildland Urban Interface (also called the WUI) where homes and lives may be at increased risk—it plays a critical role in slope stabilization, watershed cover, wildlife habitat, and nutrient cycling.

Cycles of fire

Many chaparral plant species “appear” only after a fire, when the dense shrubs have been burned away. Annual plants, such as golden eardrops (Ehrendorfia chrysantha), have seeds that need fire to germinate, and many bulb-forming plants, like mariposa lilies (Calochortus spp.), may bloom in great numbers after fires, taking advantage of abundant soil nutrients and increased light at ground level.

Seed dispersal

In chaparral's dense vegetation, some plants depend on animals to disperse seeds away from the parent plant because abiotic forces, such as wind, are not always effective. The bush poppy (Dendromecon rigida) produces seeds that have a nutrient-rich appendage, called an elaiosome, that is attractive to ants. Ants carry the seeds, with the attached food resource, back to their nest, and then discard the viable seed in their underground trash heaps. In this way, the seeds are dispersed away from the parent plant and are also protected from other seed predators.