A Secret Forest Grew for Millennia in North America

February 1, 2017

Doug Larson was not looking for old trees. The ecologist started working on the cliffs of the Niagara Escarpment because, like the tundra where he had studied mosses and lichens, they were relatively untouched by humans. It didn’t hurt, either, that his new research spot was close to his home in Guelph, Canada, a university town just over an hour west of Toronto.

Even after he and his students started studying the ecology of cliff face, it took them three years to discover a startling fact, hiding in plain sight—that the cliff’s small and gnarled cedar trees were hundreds of years old. No one would have imagined that there could still be an unknown old growth forest so close to a major urban area.

“They were overtly struggling to survive, but we thought the struggle was 60 years old, not 600 years old,” he said.

The first time the idea occurred to Larson, in 1988, he did not trust it. He had been counting the rings of a tree under a microscope, and there had been hundreds. But he could be wrong, he thought: perhaps there was some explanation, other than that this diminutive tree had been alive since before Europeans reached this continent. He didn’t sleep for three days.

The area where they had been working was on the outskirts of Toronto, and to find a forest that old in a major city was “heretical at the time,” he says. But the tree ring lab at the Lamont-Doherty Earth Observatory confirmed what they had found—centuries-old trees. The oldest had lived for approximately 700 years.

Once, it would not have been so uncommon to find trees that had lived for hundreds of years. In southern Ontario, there would have once been aged oaks, but in most places, those trees have long since been felled to make way for farms or to serve as lumber.

What we now call “old-growth” forests are simply communities of trees that have been allowed to continue on undisturbed while most of the forest around them has been thinned or cut down entirely. In North America, even places that look thickly forested to us now are often full of relatively young trees, regrown on patches of land that were farms not so long ago.

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