WERC research has explored the physiological adaptations that link the life cycles of chaparral vegetation with the natural regime of frequent brushfires. Upon reproduction, many species drop seeds that remain dormant in the soil "seed bank" until fire creates favorable growth conditions. When the area burns, these seeds receive a number of cues that may cause them to germinate. While seed germination in some species is stimulated by heat, in many others the onset of plant growth requires chemical exposure to combustion products such as charred wood.

In collaboration with California State University, Los Angeles, WERC research demonstrated that for many species, smoke can also trigger seed germination. In some species smoke alone is sufficient to induce growth, while in others a combination of factors is required. Because of the diverse cues through which vegetation may respond to fire, blazes of different intensities or degrees of smoke production may result in different plants dominating the post-fire recovery. Nitrogen oxides, which are also important components of air pollution, are the chemicals in smoke responsible for germination of some species.

Life and property losses from shrubland fires in California have been increasing in recent decades. It has long been thought that fire suppression has played the same role in chaparral shrubland as it has in forests, creating a build-up of fuels that eventually leads to more destructive fires.

A close analysis of state fire records reveals a different story, according to a WERC study. Since 1910, chaparral fire frequency has not changed and fire size has not increased. The researchers found that large, intense fires were equally common in the years before widespread fire suppression as today, and do not appear to be the result of fuels build-up. In this highly fire-prone ecosystem, suppression efforts appear not to have greatly altered normal patterns of fire incidence.

  Fire Suppression in Coastal Shrublands of Southern and Central California