Characterizing post-fire vegetation recovery of California chaparral using TM/ETM plus time-series data

A time series of normalized difference vegetation index (NDVI) data derived from 11 TM/ETM+ images was used to examine the recovery characteristics of chaparral vegetation in a small watershed near Santa Barbara, California following a fire event in 1985. The NDVI recovery trajectory was compared to a generalized recovery trajectory of leaf area index (LAI) for the same region, which was established using a chronosequence approach and TM/ETM+ data. Post-fire NDVI recovery trajectories were derived for the entire catchment and for individual vegetation types. Post-fire NDVI spatial patterns on each image date were compared to the pre-fire pattern to determine the extent to which the pre-fire pattern was re-established, and the rate of this recovery. Results indicated that the post-fire recovery trajectory for the catchment area average NDVI was similar to the previously established regional LAI trajectory based on a chronosequence approach. The NDVI recovery was disrupted by drought stress and attained pre-fire levels approximately 10 years after the fire. Individual vegetation types did not exhibit different rates of recovery and the recovery trajectories were only distinguished by the maximum post-fire NDVI observed after 10 years. The post-fire NDVI spatial pattern also showed a systematic return to pre-fire conditions, but exhibited a more substantial disruption due to drought stress than was the case for the average NDVI recovery trajectory.