Severidade de queimadas : tendências da literatura global e um estudo de caso na área de proteção ambiental Cabeceiras do Rio Cuiabá/Mato Grosso (APACRC/MT)

Abstract

Fire severity is defined as the degree of fire intensity and its impact on the ecosystem. The objective was to carry out bibliometric, scientometric and informametric analyzes of the international production on the spectral indices used in the analysis of the severity of fires, wi th the purpose of identifying the tendency of production, in addition to classifying and quantifying the severity of fires in the Environmental Protection Area of Headwaters of the Cuiabá River (APACRC), through the normalized spectral burn index (NBR) and its variations. For the survey of bibliographical productions, the Scopus database was used. A global search was carried out (internationally and without spatial coverage) of articles present in this database that contained, in the title, abstract or keyw ords, the descriptors vegetation, severity, index and burn or fire. The period of production related to the theme was from 1997 to 2021, with 374 scientific articles published in 127 journals. In the journal impact analysis, it was identified that, among t he journals, only a few had a significant impact. As for the ranking of the most cited countries, it is possible to observe the United States, in first place, with 10,377 citations and an average of 65.26 citations per article. In second place is Spain, wi th 2,354 citations and an average of 48.04 citations per article. Brazil, on the other hand, is in the 25th position, with 11 citations and an average of 5.5 citations per article. For the analysis of the burned area in the Conservation Unit (UC), pre fire scenes (before the occurrence of the burning, dated September 05, 2020) and post fire scenes (after/during the occurrence of the burning, dated on September 18, 2020). The criterion for choosing the images if the fire occurred in the year 2020. In order t o identify the degree of severity of the referred burning episode, the NBR indices and the normalized and relativized burning index (dNBR) were calculated for pre and post burning. The normalized difference vegetation index (NDVI) was also used to correla te the efficiency of the index regarding its use in the application of the severity of burns. Among the formations that comprise the study area, 18,870.57 hectares were affected by fire, with 87.51% composed of savannah formation, 11.78% of forest formatio n and 0.71% of grassland formation, the most affected part suffered low fire severity. To compare the effectiveness of the NDVI in the approach to fires, it was necessary to submit the data relating them to the information presented by the NBR classes. For this, the pixels of the relativized normalized difference vegetation index (dNDVI) were superimposed on the dNBR classes and submitted to the statistical treatment of the Tukey Test. It was concluded that, when comparing the means of dNDVI correlated to t he dNBR classes, a significant difference was observed in all areas studied, with the exception of environments where Moderate High Severity occurs when compared to High Severity. In all vegetation formations studied, the dNBR index showed that, despite it s impact on the progress of burning, almost 100% of the areas suffered low severity, leading to the conclusion that the negative impact on the regeneration of the affected area may not be very significant in this episode of burning. On the other hand, the NDVI index proved not to be effective in identifying burned areas, when compared to the NBR. However, it can be a guide to characterize the differences between the severity classes.