Assessing fire impacts on the Pantanal wetland using Sentinel-2 imagery

Abstract Background Fire is an increasingly common disturbance factor, which often results in severe damage to ecosystems and causes long-term post-fire effects. In 2020, the Pantanal wetland experienced the most catastrophic fire season over the last two decades, which led to devastating environmental impacts. Based on Sentinel-2 satellite imagery spanning a period from June to November 2020, we used the Normalized Burn Ratio (NBR) to measure the scope of 2020 fires in the Pantanal Matogrossense National Park. Additionally to burnt area estimations, we aimed to evaluate fire-induced changes in vegetation health and its post-fire recovery using Leaf Area Index (LAI), Leaf Chlorophyll Content (Cab), Canopy Water Content (CWC), Fraction of Absorbed Photosynthetically Active Radiation (fAPAR) and Fraction of Vegetation Cover (fCOVER) biophysical variables, as well as changes in lagoon water quality using Total Suspended Matter (TSM), Chlorophyll (Chl) and Kd_z90max (i.e., the depth of the water column from which 90% of the water-leaving irradiance is derived) products offered by Sentinel-2. Moreover, we conducted a vegetation and water quality recovery analysis using imagery from five months post-fire. Results Our findings suggest that approximately 73% of the Pantanal Matogrossense National Park was affected by the 2020 wildfires and experienced burns of varying severity. An estimated 59% of the total burnt area experienced high severity burns, 27.1% moderate and only 13.9% were classified as low severity. By the end of fires in November 2020, all vegetation biophysical variables indicated a substantial reduction in vegetation health across the study area. Water quality in the four studied lagoons was reduced since total suspended matter (TSM) and water transparency (Kd_z90max) decreased. Five months post-fire, vegetation as well as water quality recovered to pre-fire state, suggesting great resilience of the ecosystem. Conclusions The findings of our study contribute to the scarce research into the impacts of 2020 fires on the Pantanal wetland and provide a practical remote sensing methodology that could be applied to study fire impacts on other areas of poor access worldwide.