QUANTIFYING FIRE BEHAVIOR VERSUS SOCIETAL BENEFITS OF SOUTHERN CALIFORNIA SHRUBLANDS AND GRASSLANDS

Urban sprawl in southern California perpetually threatens native shrublands and grasslands, which intrinsically provide both biophysical and socioeconomic benefits to society. However, these vegetation types are simultaneously prone to high-intensity wildfires that lead to enormous damage to human interests. After the southern California firestorms of October 2003, new regulations were adopted that increased the mandatory vegetation clearance around structures in order to reduce fire risk, which may significantly impact the positive benefits that grasslands and shrublands provide. To address this apparent conflict, we investigated the tradeoffs between societal benefits derived from major shrubland, grassland, and woodland vegetation types in southern California versus the potential fire behavior associated with each vegetation type. Two state-of-the-art, geographic information system-based software packages were utilized in the analysis, which focused on San Diego County, California. For each of the most common grassland, shrubland, and woodland vegetation communities in the area, FARSITE was utilized to assess potential fire behavior under average and extreme weather conditions. The most extreme fire behavior was found in nonnative grasslands and scrub oak chaparral communities and least extreme in coast live oak (Quercus agrifolia) communities. Under Santa Ana wind conditions, simulated fires in almost all vegetation types burned over 3 km into a developed area in < 1 h. CITYgreen was used to quantify air pollution removal, carbon sequestration, and stormwater retention for each of the vegetation types, but was found to be largely ineffective because it calculated no measurable benefits for any non-tree vegetation types. To ensure sustainable neighborhoods in the wildland-urban interface, diverse stakeholders must create collaborative management plans that simultaneously reduce fire risk and maximize societal benefits.