In the spring following a forest fire, trees that survived the blaze explode in new growth and plants sprout in abundance from the scorched earth. For centuries, it was a mystery how seeds, some long dormant in the soil, knew to push through the ashes to regenerate the burned forest.
In the April 23 early online edition of the Proceedings of the National Academy of Sciences (PNAS), scientists at the Salk Institute and the University of California, San Diego, report the results of a study that answers this fundamental “circle of life” question in plant ecology. In addition to explaining how fires lead to regeneration of forests and grasslands, their findings may aid in the development of plant varieties that help maintain and restore ecosystems that support all human societies.
“This is a very important and fundamental process of ecosystem renewal around the planet that we really didn’t understand,” says co-senior investigator Joseph P. Noel, professor and director of Salk’s Jack H. Skirball Center for Chemical Biology and Proteomics. “Now we know the molecular triggers for how it occurs.”
Noel’s co-senior investigator on the project, Joanne Chory, professor and director of Salk’s Plant Molecular and Cellular Biology Laboratory, says the team found the molecular “wake-up call” for burned forests. “What we discovered,” she says, “is how a dying plant generates a chemical message for the next generation, telling dormant seeds it’s time to sprout.”
While controlled burns are common today, they weren’t 50 years ago. The U.S. park service actively suppressed forest fires until they realized that the practice left the soil of mature forests lacking important minerals and chemicals. This created an intensely competitive environment that was ultimately detrimental to the entire forest ecosystem.