From the Amazon to Siberia wildfires set much of the world ablaze in 2019, with some areas suffering the largest burns ever recorded. This year shows signs of a repeat. It’s not hard to see global heating’s hand at play, even as some tried to deny it, but a new study in Nature Ecology and Evolution claims the influence of logging has been overlooked.
The paper’s authors are Australian, and their focus is on the unprecedented fires that ripped through millions of hectares of Australia's forests during the Southern Hemisphere’s most recent summer. However, Professor James Watson of the University of Queensland told IFLScience their conclusions apply worldwide.
“The general processes are the same everywhere,” Prof. Watson said. “When you log a forest you open up a canopy so it gets more dried out. There is moisture loss from the soil and more wind, which dries things out more.” The loss of windbreaks allows the fires to move faster and become hotter. Moreover, Watson noted in a statement, “[Logging] can leave up to 450 tonnes of combustible fuel per hectare close to the ground – by any measure, that’s an incredibly dangerous level of combustible material in seasonally dry landscapes.”
Cool season fires are lit after timber removal to reduce fuel and encourage regrowth. However, Watson told IFLScience, “This doesn’t get rid of all of it, and it just dries the soil out more,” making an area more vulnerable to future fires.
Advocates for native forest logging often claim the industry is a defence against wildfires, but Watson told IFLScience the claim never comes with evidence to back that up, or even much logic. “The only argument is that it removes some of the wood from the system, but in the process it makes what is left more flammable.” Watson notes fire-building starts with kindling, not thick logs, and an area with a thousand regrowth saplings is far more likely to burn than one with a few mighty trees, even if it has less total wood.
Fire rips through canopies of equal height easily but is obstructed by the multi-story canopies of areas untouched for centuries.
The consequences endure. “There are places in Australia that were logged a century ago and haven’t been logged since, but they are still more vulnerable to fire,” Watson said, although some ecosystems recover more quickly.
The authors urgently call for logging to be moved from native forests to plantations, and particularly for protection of forests around towns. Watson stressed that the most urgent issue is to avoid “salvage logging” of areas that burned last summer. While promoted as a way to put dead wood that would otherwise go to waste to use, Watson says it simply increases the change of a repeat. Instead, he told IFLScience, replanting with a mix of species can help provide a safety buffer.