ASSESSING THE IMPACTS OF WILDFIRE ON VEGETATION REGROWTH: A CASE STUDY OF THE 2020 BOBCAT FIRE IN LOS ANGELES RIVER BASIN

Wildfires immediately change the ecologic landscape of an area and after years of post-fire recovery, the vegetation will attempt to return to its former state. Assessing the change in vegetation may help with understanding how hydrological components of the wildfire affected areas behave after a potential vegetation shift. This case study of the 2020 Bobcat Fire in Los Angeles River Basin of Southern California uses Google Earth Engine (GEE) to calculate the Difference Normalized Burn Ratio (dNBR) and Normalized Difference Vegetation Index (NDVI) of available Landsat images to monitor the burn severity and vegetation change from the fire’s conception to the present day. Two time series were created for the fire event, including the area inside the fire boundary and the area surrounding the fire boundary. After more than 3 years of post-fire vegetation growth, our results indicate post-fire vegetation inside the fire boundary requires more time to regrow to pre-fire vegetation conditions. All dNBR burn severity classes decreased over time as the “unburned” dNBR class rose to 60% since the start of the fire. Additionally, the average NDVI increased steadily throughout the time period reaching a peak NDVI average resembling the average of pre-fire conditions. Overall, we observe the increasing post-fire vegetation growth characterized by a decrease in burn severity and an increase in average NDVI levels. Analyzing time series of post-fire vegetation growth will be essential for future landscape management and protection from changes in water retention and soil erosion. Using GEE and currently available satellite imagery shows the accessibility of information for wildfire studies and applying these steps to other burned areas can help our understanding of the impacts of wildfires on ecosystems.