During the fire that raged on November 9, 2019 in Bobin, 350 kilometers north of Sydney, Australia. PETER PARKS / AFP
These are findings that shed light on the dramatic toll of the fires that have ravaged south-east Australia. Three years ago, between September 2019 and February 2020, fires of unprecedented proportions killed at least 33 people and destroyed 2,500 homes. They also had serious ecological consequences, destroying more than eight Millions of hectares of forest and emit more carbon into the atmosphere than the country releases each year.
However, a study published on Thursday September 1st in the journal Remote Sensing of Environment confirms that by the end of 2020 these emissions were reabsorbed by vegetation, which regrowed very quickly. “As for the biomass, everything that disappeared during the fires was recovered the following year,” explains Jean-Pierre Wigneron, a researcher at the National Research Institute of Agriculture, Food and Environment (INRAE) and one of the authors of the paper. These lights were therefore CO2 neutral. »
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While the loss of forest cover is clearly visible, the loss of vegetation, measured in terms of biomass, is much more difficult to estimate. For the first time, the study assesses the amount of grass, shrub and eucalyptus trees lost to fire, drought and particularly high temperatures, in tonnes per hectare, and the status of this biomass one year after these extreme events.
“climate happiness”
According to estimates by researchers from Inrae, the Commissariat of Atomic Energy and Alternative Energies and several international universities, which correspond to the results of other scientific works, about 15% of the biomass of the forest area was lost in the 2019-2020 season, around 200 million tons of carbon released into the atmosphere. About half (90 million tons) is due to fires, the other half (110 million) to drought and record temperatures, with weather conditions having a major impact.
In 2020, on the other hand, the amount of biomass has increased significantly, allowing more than 260 million tons of carbon to be stored. A very rapid recovery that can be explained by a combination of factors: Eucalyptus species, the majority in Australian forests, are known to ‘recover’ extremely quickly after a fire. At the same time, 2020 saw above-average rainfall, which favored the recovery of surviving trees and the growth of understory.
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