Understanding the conditions that create severe tropical forest fires

photo by Paulo Brando

The dynamics of fire and vegetation in tropical forests is the subject of a paper just published in the journal Global Change Biology by WHRC scientists Paulo Brando and Michael Coe with collaborators from the Amazon Environmental Research Institute (IPAM).

“This is part of a larger project designed to identify potential climatic thresholds that create conditions for high-intensity, catastrophic tropical forest fires,” explained Dr. Brando. “We wanted to isolate the effects of fuel on fire behavior in forest carbon cycling.” The scientists manipulated fuel loads in experimental fires in southeastern Amazonia and found that increasing fuel alone was unlikely to create conditions conducive to such disastrous fires during non-drought years, although fires were more extensive where fuels were added.

According to Dr. Brando, while the researchers’ experimental fires apparently fell at the low end of the spectrum of intensity due to relatively moist air conditions, their previous experimental fires triggered abrupt, nonlinear forest responses driven by fire-drought interactions. “This contrasting pattern of fire intensity and severity points to synergies between fuel amount and climate that can create non-linear conditions for high-intensity, catastrophic fires,” he said.

“Contrary to our hypotheses,” Dr. Brando explained, “the experimental fires triggered (i) only minor losses in carbon stocks and (ii) significant increases in wood increment. As a result, two years after the experimental fires, carbon stocks and cycling were quite similar between the burned and unburned sites.”

“With this information in hand, we have a better ability to understand and model the impacts of climate change on fire regimes of tropical forests,” said Dr. Coe.

Link to the abstract »

WHRC is an independent research institute where scientists investigate the causes and effects of climate change to identify and implement opportunities for conservation, restoration and economic development around the world.