Fig 1.
Ecoregions of California, including Southern California Mountains (SCM), Southern California Coast (SCC), Central California Foothills (CCF), Klamath (K), Cascades (C), East Cascades (EC), and Sierra Nevada (SN).
Areas in white represent coastal zones, Central Valley agriculture and desert areas. The coastal zone in northwest California and the desert zone in the south and northeast are removed from analysis due to rare occurrence of wildfire. The Central Valley was removed from the analysis due to the predominance of crop land cover, irrigated agriculture, and the high frequency of low severity fires that are filtered out after the application of burn severity thresholds. Ecoregions of California (Griffith, 2016): https://doi.org/10.3133/ofr20161021.
Table 1.
Land cover characteristics for the unburned regions of each ecoregion averaged for 2003–2020.
Fig 2.
All burned areas by month for the time period of January 2003 –December 2020 (a) and all burned area by burn severity class for the time period of January 2003 –December 2020 (b). The seven ecoregions are larger polygons represented in low saturated colors (as in Fig 1). For panel (a), a binary burned-unburned mask was generated for each month of the MCD64A1 Monthly Burned Area product and the sum for each month calculated. For panel (b), RdNBR was derived from MOD13Q1 surface reflectance data, burn severity thresholds were applied, and the spatial distribution of burn severity plotted (see Methods).
Table 2.
Burned area characteristics for each ecoregion averaged for the period 2003–2020.
Fig 3.
California ecoregion specific total annual burned area for 2003–2020 based on MODIS MCD64A1 approximate date-of-burn product.
Ecoregions are split into roughly southern (top) and northern (bottom) California. Total burned area each year represented in square kilometers.
Fig 4.
Histograms for RdNBR averaged for the entire study period of 2003–2020.
Symbols mark the lower limits of low, moderate, and high burn severity class respectively; (a) RdNBR by ecoregion, and (b) RdNBR by individual vegetation type. Burn severity thresholds for each ecoregion were calculated from the cumulative frequency distribution of RdNBR pixel values (see Methods).
Table 3.
RdNBR low, moderate, and high burn severity thresholds for each ecoregion derived from RdNBR cumulative distributions.
Table 4.
Pearson temporal correlations (r values) between average early-summer burn severity (RdNBR) and burned area averages of six biophysical variables within each of the seven ecoregions of California.
Fig 5.
Prefire EVI and five-year early-summer postfire trajectory (a-g). Average early-summer postfire EVI for one-year pre-fire through five-years post-fire for each ecoregion SCM, SCC, CCF, K, C, EC, and SN. Prefire and postfire EVI are burned area averages.
Fig 6.
Prefire albedo and five-year early-summer postfire trajectory (a-g). Average early-summer surface shortwave albedo response for the first-year pre-fire through five-years post-fire for each ecoregion SCM, SCC, CCF, K, C, EC, and SN. Prefire and postfire albedo are burned area averages.
Fig 7.
Prefire land surface temperature and five-year early-summer postfire trajectory (a-g). Average early-summer land surface temperature first-year pre-fire through five-years post-fire for each ecoregion SCM, SCC, CCF, K, C, EC, and SN. Prefire and postfire LST are burned area averages.