Fire Regimes in Southern California
Located along the southern and central coasts of California, the chapparal biome consists of semi-arid shrubland with plants that have small, hard leaves that are incredibly quick to burn. Many plants of this region have flammable oils and resins in their leaves and their seedlings require intense fires to germinate. In this way, the plants of the chapparal ecosystem are well adapted to a cycle of fire. The fires that spread through the chapparal biome are typically crown fires in which fire rapidly spreads from treetop to treetop ahead of ground fires. The chapparal fire regime is characterized as a crown fire regime that quickly spreads and burns everything and is primarily driven by the Santa Ana winds, which blow inland from Nevada and Utah and are characteristically strong, extremely dry downslope winds. Because of the difficulty of acquiring historical evidence for fire regimes, as opposed to modern methods such as aerial photography and satellite imagery, there is debate among researchers about the historical fire regime of the chapparal biome. According to some researchers, fire suppression destroyed what had previously been a fire regime where frequent, low-intensity fires precluded large, catastrophic ones. However, through an analysis of historical records such as written accounts and tree rings, researchers have concluded that the chapparal fire regime has always been prone to large crown fires and is similar to modern fire patterns in the region.[3]
[1] “Characterizing Fire Regimes,” University of California
[2] “Fire Mosaics in Southern California and Northern Baja California,” Science, vol. 219, no. 4590, 1983, pp. 1287–94 (March 18, 1983)
[3] “Historic Fire Regime in Southern California Shrublands,” Conservation Biology, vol. 15, no. 6, 2001, pp. 1536–48 (December, 2001)