Combining remote sensing and field data to assess recovery of the Chilean Mediterranean vegetation after fire: Effect of time elapsed and burn severity

It has been debated if Chilean sclerophyllous vegetation can recover after fire of different severity and short and long term. We evaluated the resiliency of this vegetation type after single-occurrence fires of different severities that occurred 30, 20 and 10 years in Central Chile before the study. Two approaches were followed: satellite image analysis and vegetation sampling. Wildfires that occurred between 1985 and 2015 were identified based on Landsat images. We selected 30 sites burned by a single fire in either 1985, 1995 or 2005, and that was not converted to another land use by 2015, then determined the percentage cover by vegetation type. We recorded or estimated the independent variables of burn severity, slope, altitude, pre-fire vegetation type and latitude of the sites. Composition, richness, and abundance of adult and regeneration of woody vegetation and herbaceous cover were sampled. Generalized linear models were used to evaluate the effect of the independent variables and the time elapsed since the fire on vegetation recovery. The proportion of dense vegetation forest cover was significantly higher with more time elapsed since the fire, while semi-dense forest/shrubland and open shrubland vegetation cover returned to pre-fire levels more quickly. The richness and abundance of regenerated woody species was significantly greater with more time elapsed since the fire. However, no relationship was found between species richness and abundance of adult woody species and time elapsed post-fire. We found that vegetative recovery over time was not related to burn severity. Forested and mixed forest/shrubland cover is reached 10–20 years after the fire, if no further intervention occurs. Richness and species abundance was similar to that of unburned sites after 20 or more years post-fire. This study provided evidence that forest vegetation in the Chilean Mediterranean ecosystem is resilient to fires of at least low and medium intensities.