Assessing postfire recovery of chamise chaparral using multi-temporal spectral vegetation index trajectories derived from Landsat imagery

A primary finding is that the Scaled Recovery Metric (SRM), a variant of the Regeneration Index which incorporates the pixel-specific SVI value immediately after fire, is a particularly useful indicator of postfire recovery based on time-sequential SVI trajectories and facilitates inter-site comparisons. Time series of several SVIs (especially NDVI and NBR2) provide statistically significant (p < 0.05) indications of postfire recovery outcomes when postfire recovery metrics are applied; NDVI and NBR2 are also sensitive to the gradual regrowth of chamise up to 12 and 19 years postfire, respectively. Normalization by unburned control plots reduces the correlation of Landsat SVIs with annual precipitation by 25 to 70% and enhances recovery signals, but locating suitable control plots was difficult in many parts of our study area. NBR2 is useful for postfire recovery assessment without normalizing by control plots. This study provides an overview of some advantages, limitations, and technical considerations for using postfire regrowth trajectories from Landsat imagery to assess long-term impacts of fire on chamise chaparral.