THE BASICS: FIRE IN THE CHAPARRAL
2. Fires more than once every 20 years, or during the cool season by prescribed fire, can eliminate chaparral by first reducing its biodiversity through the loss of fire-sensitive species, then by converting it to non-native weedlands (called type-conversion).
3. Being dense, impenetrable, and prone to infrequent, large, high-intensity wildfires is the natural condition of chaparral. It's not the fault of past fire suppression, poor land management, "unnatural" amounts of vegetation, or environmental laws as some claim.
4. The age and density of chaparral has little to do with the occurrence of large fires. Large fires in California shrublands are driven primarily by weather, such as Santa Ana and sundowner winds, and multi-year droughts.
5. Chaparral has a high-intensity, crown fire regime, meaning when a fire burns, it burns everything, frequently leaving behind an ashen landscape. This is in contrast to a mixed-severity fire regime found in dry Ponderosa pine forests in the American Southwest where fires burn in large and small patches, where trees are either completely burned in a crown fire or only scorched as the understory burns.
6. Native Americans did burn the landscape for various purposes in the past. Some of their burning practices likely eliminated native shrublands along the coast through type-conversion (see #2 above). However, their burning activity did not prevent the occurrence of large, infrequent, high-intensity chaparral fires. Such fires have always been a natural and inevitable part of the landscape.
How Chaparral Plants Respond to Fire
There are five basic strategies
plants use to respond to fire in the chaparral.
1. Obligate Seeders
2. Obligate Resprouters
3. Facultative Seeders
4. Fire Followers
- A CRITICAL DIFFERENCE - FOREST FIRES VS. SHRUBLAND FIRES
For more details on this important subject, please see our Threats to Chaparral Page.
The Natural Fire Return Interval
The highest lightning frequencies in the United States occur in the Southeast and the Southwestern regions. Both of these areas have forests that have short fire return intervals - long leaf pine in the Southeast, ponderosa pine in the Southwest. The lightning frequency in California is extremely low. For much of the state it borders on being non-existent. This is a good proxy for natural fire rotations: 135 years or more for coastal areas around San Francisco, to shorter rotataions in the Sierra Nevada Mountains where lightning is more common.