Remote evaluation of the recovery of vegetation affected by forest fires

Abstract

Forest fires alter ecosystem processes and interactions. However, not all fires are the same, some are more severe than others, their impact on the vegetation varying according to the degree of severity. Therefore, it is important to have information that allows sizing these impacts and supports the implementation of management strategies. However, monitoring the impact of fire is not an easy task, much less monitoring the response of the ecosystem over the years. Accordingly, the objective of this work was to implement satellite technology to monitor the dynamics of forest cover recovery in areas impacted by forest fires, in order to direct ecosystem restoration strategies. For this, the difference (before and after the fire) of the normalized burning ratio (dNBR) was defined to determine the severity of a fire that occurred in the Sian Ka'an Biosphere Reserve in 2019. Subsequently, the dynamic of ecosystem recovery was evaluated, through the analysis of a series of images, using the following indexes: a) Normalized Difference Vegetation Index (NDVI); b) Normalized burn ratio (NBR); c) Normalized Thermal Burnup Ratio (NBRT); d) Burned Area Index (BAI). A change in the reflectance value was observed in the burned area after the fire, which was restored over time. However, although the values show a recovery of the vegetation, in the field the ecosystem is made up of different species from those that were present before the fire, therefore, by means of the spectral signature of the vegetation, an image was generated showing the difference in the density of vegetation, which favors the understanding of the effects of fire and helps define priority areas to direct restoration actions.