How much carbon and aerosols are released during Santa Ana fires?

Field measurements (UCI and JPL)

We will make field measurements of combustion completeness, carbon loss, plant mortality, and plant community composition along gradients of burn severity, fire frequency, stand age, and vegetation type at field sites in Southern California. We will build on a series of ongoing field programs and research sites in Southern California’s Santa Ana, San Jacinto, and Santa Rosa Mountains (we have active research permits for the Irvine Ranch Land Reserve, which encompasses the northern part of the Santa Ana Mountains, and the San Bernardino National Forest, which encompasses the San Jacinto and Santa Rosa Mountains). We have already identified and visited preliminary sites that span gradients in burn severity, past fire occurrence (number of past burns and time since last burn), and vegetation type for the Santiago Fire, which occurred in the Santa Ana Mountains (October 2007), and the Esperanza Fire, which occurred in the San Jacinto Mountains (October 2006). Similarly, we have identified and visited plots that span gradients in time since last burn (chronosequences) for the Santa Ana and San Jacinto Mountains. We have also identified control stands for these burns (adjacent, well- matched areas that are just outside of the fire perimeters). Our final collection of plots will likely include areas burned in the 2009 season. Our main goal in finalizing plot selection will be to ensure the plots are as well matched as possible. We will target sites that differ only in the main variable of interest (we will try to hold other variables, such as soil type, aspect, slope, and elevation, constant). The selection of sites is being done in a Geographical Information System, taking into account fire history, topography, vegetation cover, seasonal and absolute vegetation indices, and historical (both Landsat and aerial photography) imagery. The plots will be visited in summer 2010 and surveyed for location (GPS), burn intensity (minimum size of unburned twigs), previous woody species composition and density, and remaining coarse wood debris. The observations within burns will be compared with nearby control stands to calculate combustion completeness and carbon loss. The plots will be revisited at least once a year (in summer; after the main growing season) and surveyed for mortality and survival of woody perennials (tagged shrubs in permanent plots), cover by species (100-m line transects for large perennials; point intercept quadrats for herbaceous), herbaceous production (clipped quadrats sorted for exotics and natives), and FPAR/LAI (LAI-2000). These observations will be used to determine the mortality and immediate recovery from fire as a function of burn severity, past fire frequency, and vegetation type. Measurements along gradients in time since last fire (chronosequences) will be used to determine long-term recovery from fire. The field measurements will be made in close coordination with airborne remote sensing observations. MODIS/ASTER Airborne Simulator (MASTER) acquired imageries over 14 of the October 2007 fires including the Santiago fire. These data were acquired shortly after the fires, with repeat acquisitions at all sites after 6 months and 1 year. Our budget includes summer acquisitions of MASTER data over these fires in 2010 and 2012.