CONICET | Buscador de Institutos y Recursos Humanos

This study evaluates the occurrence of dry and wet events and their relationship with fires insouthern Pampas, Argentina. The intensity and magnitude of dry and wet events were determined based on theregional series of the Standardized Precipitation and Evapotranspiration Index (SPEI) for the 2000-2021 period.The data obtained were related to the El Niño Oceanic Index (ONI) to analyze the incidence of El Niño and LaNiña events in generating them. Fires in the region were detected using remote sensing techniques, consideringthe number of events, their intensity, extent, and duration. The southern Pampas experiences marked rainfallvariability, with 15 dry events, 11 wet years, and 2 standard years recorded for the period analyzed. Extreme dryyears were, on average, more intense (SPEI = -2.14) and occurred mainly during the negative ONI phase. Incontrast, extreme wet years exhibited lower intensity (SPEI = 1.98), and only the most intense ones were relatedto neutral ONI phases. We analyzed a representative extremely dry (ED) and an extremely wet events (EW) tointerpret the relationship between climate variability and the spatiotemporal variability of fires in the region. Itwas observed that during the EW event (2014-2015, SPEI = 1.52, and El Niño event until 2015) the number offires was higher compared to an ED event (2008-2009, SPEI = -2.22, and La Niña event during 2008), with 460and 205 fires, respectively. The intensity was higher in the EW (302.6 and 31.5 MW), while the area presentedconsiderable differences (1722 and 815.5 km2, respectively). Finally, the duration of the fires was shorter in EDthan in EW (6 and 8 months, respectively). These results were related to vegetation health (NDVI = 0.29 and 0.41 and EVI = 0.15 and 0.21 in ED and EW, respectively) and changes in land covers. This study provides a solid database for future research efforts and sustainable land management plans.

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