New research shows that fern savannahs helped sustain massive wildfires across northwest Europe during the end-Triassic mass extinction 201 million years ago. The study links rising temperatures and forest collapse to a prolonged period of fire activity fueled by the plants themselves. Findings were published July 21 in Nature Geoscience.
An international team led by geologists at Utrecht University examined sediment from four drill cores, including a 640-meter core from the United Kingdom. Researchers measured fossil charcoal, polycyclic aromatic hydrocarbons and a new Palynomorph Darkness Index to track ancient fire activity.
The data revealed a sharp rise in wildfires that coincided with the spread of ferns after forests collapsed due to volcanic eruptions and global warming of 5 to 10 degrees Celsius. Ferns regrew quickly from root systems after fires, creating fuel for repeated blazes over an interval estimated at 40,000 to 300,000 years.
"Ferns responded to and delivered the fuel that fanned the flames, triggering repeated massive wildfires," said Dr. Bas van de Schootbrugge of Utrecht University. The study suggests the combination of climate change, deforestation and opportunistic species created conditions for prolonged environmental stress.