The World's Oldest Forest Is Here in the Hudson Valley
The discovery of fossil trees in Cairo, New York dates the forest to approximately 386 million years old.
Oblique view of the site showing large rooting systems
Photo by William Stein and Christopher Berry
It’s hard to step foot in the Hudson Valley without coming across some sliver of history. Tales of centuries past abound from Albany to Westchester, popping up in local museums, historic houses, and even street signs. Spanning from the age of the dinosaurs and the Revolutionary War to heyday of the Borscht Belt and the Irish Alps, the whispers of days long gone live on throughout the region.
Turns out, they live on quite a bit longer than everyone thought.
In a new study published this December in Current Biology, scientists discovered evidence of the oldest forest in the world right here in the Hudson Valley. Their report, which centers around a site in Cairo, is the latest effort in a research project that began in 1993. It’s a collaborative effort between Binghamton University’s William Stein, Cardiff University’s Dr. Christopher Berry, the New York State Museum, and the New York Paleontologists.
Working together, the group estimates the Hudson Valley forest to be approximately 386 million years old.
Overview of well-preserved Archaeopteris root system, left, possible Stigmarian Isoetalean lycopsid, right. Photo by WIlliam Stein and Christopher Berry
While the discovery of the forest’s age is new for 2019, the group’s research in Cairo is not. After beginning studies in the region in 1993, the collective made significant inroads in 2007 and 2008 when they learned to recognize the bases of two types of fossil trees. According to Berry, one is the large rooting system of the Archaeopteris tree, while the other is the dish-like imprint of the Cladoxylopsid tree, which contains hundreds of radiating roots.
“These Cladoxylopsid trees had their origin a few million years earlier and are thought to be the first type of tree on the planet,“ Berry explains. Two years later, in 2010, Stein and Frank Mannolini from the New York State Museum recognized the same type of tree bases coming from the mud at the bottom of Gilboa’s Riverside Quarry, which dates to the Devonian period. They focused their research in Gilboa for a number of years, since it was widely considered the world’s first forest and contains visible tree fossils. At Cairo, on the other hand, only root impressions are still visible.
Overview of Archaeopteris in greenish overwash sediment. Photo by William Stein and Christopher Berry
In the newest segment of the study, Stein and his team mapped around 3,000 square meters of the historic forest in Cairo. Based on an analysis of the two principal trees by Berry and Stein, they determined the forest to be close to 400 million years old.
In doing so, they also identified what the trees in question looked like. According to Berry, the Archaeopteris was a large tree with broad green leaves, a solid trunk, and a modern-seeming root system. The Cladoxylopsid, meanwhile, had branches with twiggy leaves attached to a mostly hollow trunk supported by ribbon-like roots. They both grew in soil that was seasonally dry.
While the group’s discovery in Cairo is significant in itself, it’s even more noteworthy because it refutes the previously accepted information that the site of Gilboa, a mere 40 minutes away, was the oldest forest in the world. In fact, the Gilboa forest is a few million years younger and had soil that was permanently wet. Unlike the Cairo forest, the Gilboa one saw Cladoxylopsids as the dominant trees, with nary an Archaeopteris in sight.
Eospermatopteris root system in overwash sediment. Photo by WIlliam Stein
So what does the discovery mean in the context of the Hudson Valley’s natural history?
“What we are really seeing here, taking into account all the evidence, is that there were different types of forests growing in different types of environments on the Catskill Delta during this time,” Berry explains.
Next up, he and Stein are collaborating with researchers from Sheffield University in the United Kingdom to analyze how the trees growing during that time impacted the soil and its nutrients.
“Soil forming processes, including the activity of roots and their associated fungi, were important in that they are likely to have increased the rate at which forest growth drew down carbon dioxide from the atmosphere,” he notes. “We are trying not only to understand the early forests and trees and what they looked like, but also how they impacted the evolution of the planet.”