(ORDO NEWS) — Scientists have found traces of the oldest forest fires thanks to 430-million-year-old charcoal deposits in Wales and Poland. They give us valuable information about what life was like on Earth during the Silurian period.
In those days, plant life was largely dependent on water for reproduction and would most likely not have developed in regions that were dry for part or all of the year. The wildfires discussed in the study could burn very short vegetation, as well as rare knee- or waist-high plants.
The researchers say the landscape would not have been dominated by trees, but by ancient fungal prototaxites. Not much is known about the fungus, but it is believed that it could grow up to nine meters (or almost 30 feet) in height.
“Now it seems that our evidence for fires is exactly the same as our evidence for the earliest macrofossils of land plants,” says paleobotanist Ian Glasspool of Colby College in Maine. plants, a fire occurs almost instantly.
Forest fires need fuel (plants), an ignition source (which in this case would be lightning strikes), and enough oxygen to burn.
That the fires could spread and leave charcoal deposits suggests that Earth’s atmospheric oxygen levels were at least 16 percent, the researchers say.
Today this level is 21 percent, but it has changed dramatically over the course of Earth’s history. Based on their analysis, the team believes that atmospheric oxygen levels 430 million years ago could have been 21 percent or even higher.
This is all very useful information for paleontologists. It is hypothesized that increased plant life and photosynthesis would have contributed more to the oxygen cycle during these wildfires, and knowing the details of this oxygen cycle over time gives scientists a better idea of how life may have evolved.
“There must have been enough vegetation in the Silurian landscape for wildfires to spread and leave traces of this wildfire,” says paleontologist Robert Gastaldo, also of Colby College.
“At the time we were sampling, there was enough biomass around to provide us with wildfire data that we can identify and use to accurately determine vegetation and process over time.”
The landscape of ancient Europe looked very different hundreds of millions of years ago, and the two sites the researchers used for their analysis must have been on the ancient continents of Avalonia and Baltica at the time these wildfires were raging.
Forest fires then, as now, would have made a significant contribution to the carbon and phosphorus cycles, as well as to the movement of sediments on the Earth’s surface. It’s a complex combination of processes that requires a lot of unpacking.
The discovery broke the previous record for the oldest wildfire on record by 10 million years, and also highlights the importance wildfire research can have in compiling the history of the Earth.
“Wildfire has long been an integral component of Earth system processes, and its role in these processes has almost certainly been underestimated,” says Glasspool.
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