Monitoring post-fire vegetation recovery in the Mediterranean using SPOT and ERS imagery

Abstract. This study examined the effect of two different forest fires 19 and 23 years ago on theMediterranean island of Thasos. An object-based classification scheme was developed to map the major land-cover types using multi-temporal Système Pour l’Observation de la Terre (SPOT) and European Remote-Sensing (ERS) (C-band VV) images covering the time period from 1993 to 2007. The developed scheme mapped the post-fire land-cover types accurately: 0.84 Kappa coefficient and 90.5 % overall accuracy. The use of the ERS backscatter coefficient contributed to decreasing the commission errors related to the mapping of forested areas and to overcoming misclassifications that occurred between forested areas and shrublands located in shadowed areas. Results indicated that the forest regeneration rate is rather slow, especially in areas where the degree of burn severity was high while the largest part of the burned area is, to date, covered by low vegetation and shrubs. Nevertheless, a gradual shift from low vegetation to shrubland was observed. A preliminary investigation on the use of the ERS backscatter coefficient and the Normalised Difference Vegetation Index to monitor forest regeneration revealed that the backscatter coefficient could provide information related to changes in dense regenerating pine forests for the first 18 years after the fire event, whereas the Normalised Difference Vegetation Index was found to be sensitive to the regenerating forest understorey vegetation. However, further investigation is needed to confirm these findings