385-million-year-old tree root reveals world's oldest modern forest

Dec. 20 (UPI) -- The discovery of ancient tree roots in the Catskills, near the town of Cairo, New York, suggests modern forests emerged earlier than scientists thought. Researchers described the 385-million-year-old root system in a new paper, published this week in the journal Current Biology.

Though seed plants wouldn't arrive for another 10 million years, the roots suggest trees with leaves and wood were growing nearly 400 million years ago, during the middle of the Denovian Period.

"The Devonian Period represents a time in which the first forest appeared on planet Earth," lead study author William Stein, professor of biological sciences at Binghamton University, said in a news release. "The effects were of first order magnitude in terms of changes in ecosystems, what happens on the Earth's surface and oceans, CO2 concentration in the atmosphere and global climate. So many dramatic changes occurred at that time as a result of those original forests that, basically, the world has never been the same since."

In 2012, Stein and his research partners discovered the ancient footprints of what became known as the world's oldest forest, the Gilboa forest. The newly discovered roots, however, found not far from the Gilboa site, are even older.

The Cairo forest is not only older, but quite different. The ancient root system boasts three unique components, reflecting a heterogeneous composition -- the type of diversity that characterizes modern forests.

One of the three different root systems in the Cairo forest anchored a palm tree-like species called Eospermatopteris. The species was also found at the Gilboa site, suggesting the tree was an adaptable, weed-like species.

Researchers also found the roots of Archaeopteris, a species that reproduced using spores but featured seed-like structures. Archaeopteris is the earliest plant species known to form leaves and woody tissue.

"Archaeopteris seems to reveal the beginning of the future of what forests will ultimately become," Stein said. "Based on what we know from the body fossil evidence of Archaeopteris prior to this, and now from the rooting evidence that we've added at Cairo, these plants are very modern compared to other Devonian plants. Although still dramatically different than modern trees, Archaeopteris nevertheless seems to point the way toward the future of forests."

Scientists also found a third species belonging to the class Lycopsida, one researchers previously thought didn't arrive until the Carboniferous Period, which lasted from 359.2 to 299 million years ago.

"What we have at Cairo is a rooting structure that appears identical to great trees of the Carboniferous coal swamps with fascinating elongated roots. But no one has yet found body fossil evidence of this group this early in the Devonian." Stein said. "Our findings are perhaps suggestive that these plants were already in the forest, but perhaps in a different environment and earlier than generally believed. Yet we only have a footprint, and we await additional fossil evidence for confirmation."

While researchers hope to continue uncovering more details about the makeup and evolution of ancient forests in the Catskills, they expect studies elsewhere in the world to reveal additional secrets and provide important context to their work.

"It seems to me, worldwide, many of these kinds of environments are preserved in fossil soils. And I'd like to know what happened historically, not just in the Catskills, but everywhere," said Stein. "Understanding evolutionary and ecological history -- that's what I find most satisfying."