Increasingly intense fire seasons harming carbon storage abilities of forests

Feb. 25 (UPI) -- Across the world, fire seasons are growing longer and more intense. New research suggests that as fires burner bigger, hotter and more frequently, forests and their carbon storage capabilities are suffering.

Researchers surveyed data from around the world to understand how changes in wildfire frequency are affecting ecosystems. They found fires are driving significant changes in diversity and abundance of tree species in forests all over the world.

The analysis, published Thursday in the journal Nature Ecology and Evolution, suggests savannah ecosystems, which experience extreme wet and dry seasons, are especially sensitive to changes in fire frequency and intensity.

"As fire frequency and intensity increases because of climate change, the structure and functioning of forest ecosystems are going to change in so many ways because of changes in tree composition," lead study author Adam Pellegrini, lecture in plant sciences at the University of Cambridge, said in a news release.

Because fast-growing trees quickly generate new biomass, they're able to suck up more carbon than slow-growing trees. Unfortunately, slow-growing trees with thicker bark tend to be more resilient to fire.

"As climate change causes wildfires to become more intense and droughts more severe, it could hamper the ability of forests to recover -- reducing their capacity for carbon storage," Pellegrini said.

The changes identified by the new study could force policy makers and forest managers to alter preservation and restoration plans designed to slow climate change.

"Planting trees in areas where trees grow rapidly is widely promoted as a way to mitigate climate change," Pellegrini said. "But to be sustainable, plans must consider the possibility of changes in fire frequency and intensity over the longer term."

"Our study shows that although wetter regions are better for tree growth, they're also more vulnerable to fire," Pellegrini said. "That will influence the areas we should manage to try and mitigate climate change."

When fires destroy a forest, they don't just harm trees. Fires also diminish soil health, granting an advantage to slow-growing trees capable of subsisting on fewer nutrients.

As these more resilient but less dynamic trees come to dominate fire-ravaged forests, nutrient recycling slows to a halt, depressing biological productivity.

For millions of years, forests and their inhabitants have adapted to survive and even take advantage of wildfires and their ecological effects.

Historically, carbon released by wildfire is reabsorbed by forests as they regenerate, but human activities and climate change are threatening to disrupt this natural balance.

"As fire frequency and intensity increases because of climate change, the structure and functioning of forest ecosystems are going to change in so many ways because of changes in tree composition," Pellegrini said.

"More fire-tolerant tree species are generally slower growing, reducing the productivity of the forest. As climate change causes wildfires to become more intense and droughts more severe, it could hamper the ability of forests to recover -- reducing their capacity for carbon storage," Pellegrini said.