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The 2015 El Nino event touched a million hectares of forests in central Amazonia. Although they touched an area more than five times larger than the Mendocino wildfires in California, these attracted little attention from national or international media at that time. Credit: Adam Ronan
The carbon losses caused by the El Niño forest fires in 2015 and 2016 could be up to four times greater than predicted, according to a study of 6.5 million hectares of forests in the Brazilian Amazon.
New research, published in a special issue of the journal Philosophical Transactions of the Royal Society B, revealed that forest fires in the Amazon in 2015 and 2016 resulted in CO2 emissions three to four times higher than comparable estimates in existing global fire emission databases.
This discovery is part of a series of results published this week by researchers from Lancaster University who were working at the heart of one of the worst wildfire sites that the Amazon has ever seen. known for a generation.
The researchers claim that uncontrolled fires in the undergrowth – or at ground level – of tropical rainforests during extreme droughts are an important and poorly quantified source of CO2 emissions.
The study, "Quantifying the Immediate Carbon Emissions of El Niño Fires in Tropical Rainforests," focused on an area of 6.5 million hectares, of which nearly one million were in the tropics. hectares of primary and secondary forests burned during the 2015-2016 El Niño size of half of Wales).
Although the analyzed area covers less than 0.2% of the Brazilian Amazon, these fires resulted in an estimated CO2 emissions of more than 30 million tonnes, three to four times higher than the comparable database estimates. global fire emissions.
Lead author Kieran Withey of Lancaster University said: "Uncontrolled wildfires in tropical rainforests during extreme droughts are an important and poorly quantified source of CO2 emissions – high immediate CO2 emissions. This analysis only covers 0.7% of Brazil, but the amount of carbon lost is equivalent to 6% of the annual emissions of Brazil as a whole in 2014. "
By the end of 2015, Santarém, in the Brazilian state of Pará, was one of El Niño's epicenters. The region experienced a severe drought and many forest fires and researchers were working in the middle. Scientists from ECOFOR, the international research project led by Professor Jos Barlow of Lancaster University, have set up 20 study sites in Santarém, eight of which have been set on fire.
The research team quickly realized that she had the opportunity to document in detail how a forest reacted to fire on this scale.
Dr. Erika Berenguer of Oxford and Lancaster University and her colleagues found that, following the fires, the surviving trees grew much more than those in the unburned forests, regardless of their previous human disturbance. On average, trees in burned forest areas increased by 249% more than trees in drought-stricken forests, but not by fire. Although the growth rate is good news, this strong increase seems to be a relatively short-term reaction.
Professor Jos Barlow of Lancaster University said: "Only a few trees can survive these fires, as the Amazonian forests have not evolved in parallel with this threat, the results of tree mortality."
Meanwhile, Camila VJ Silva of Lancaster University conducted research on 31 other plots burned across the Brazilian Amazon, which showed that even 30 years after a fire, the seemingly recovered forests still contain 25% less carbon than neighboring primary undisturbed forests.
"Forest fires in tropical rainforests can significantly reduce forest biomass for decades by increasing mortality rates of trees with high wood density (such as Brazil nuts or mahogany), which store the greater amount of biomass in old-growth forests Our work has shown that wildfires slow down or significantly slow the recovery of Amazonian forests after a fire.
"Overall, our combined results underscore the importance of taking into account forest fires in Brazilian forest conservation and climate change policies, with climate models predicting a more sustainable future. The fires are likely to become more hot and drier for the Amazon Basin.If public policies do not take into account forest fires, fire return intervals will be shorter as forests are unable to recover their carbon stocks. "
Explore further:
A devastating human impact on the Amazon rainforest revealed
More information:
* Silva C.V.J., Aragao, L.E.O.C., Barlow, J. et al. (2018). The Amazonian forest fires caused by the drought cause a disruption on the decennial scale of forest carbon dynamics. Philosophical Transactions Royal Society B. DOI: 10.1098 / rstb.2018.0043
* Withey, K. Berenguer, E., Palmeira, A. et al. (2018). Quantify the immediate carbon emissions from El-Niño-mediated forest fires in tropical moist forests. Philosophical Transactions Royal Society B. DOI: 10.1098 / rstb.2017.0312
Berenguer, E. et al. (2018) Tree growth and carbon accumulation in Amazonian forests modified by humans as a result of droughts and fires. Philosophical Transactions Royal Society B. DOI: 10.1098 / rstb.2017.0308
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