Suzanne Simard has spent more time hiding from grizzly bears than most people, and she did it for science. Working in Canada in the 1990s, Simard set out to answer a question: Why do Douglas firs need birch trees around?
The problem came up when she was working in forest management. Foresters regularly remove birch trees from an area to give the more valuable Douglas fir trees extra access to sunlight and water. But when the birches are out of the way, the firs fare worse instead of better.
The firs must have been relying on the birches somehow, Simard realized. Each tree may look like an independent organism, but trees occupy another world underground. When two root systems overlap, and with the help of some beneficial fungi, a trade route can open up between trees.
Simard’s first experiment involved 80 saplings each of three species: birch, firs and cedars planted together. The birches were covered in plastic bags filled with a radioactive form of carbon dioxide gas. After leaving them for an hour, Simard checked the trees with a Geiger counter. As expected, the cedars didn’t elicit any sound. The birches set it off, showing they had absorbed the radioactive gas. But the firs set off the Geiger counter, too. They had radioactive carbon, and the only possible source was through the roots of the birch trees.
Decades later, trees are still surprising us. In July, a research team in New Zealand announced that they had discovered a tree stump that was still alive. Like the birch supporting the firs, the surrounding forest was supporting the tree stump with water and nutrients that it couldn’t move on its own, without leaves.
The revelation that trees can, and do, collaborate might change the forestry industry for the better. Now, Simard advocates for forestry solutions that take new research in forest ecology into consideration so that forests can be resilient to threats such as disease and climate change. A professor of forest and conservation sciences at the University of British Columbia and a science communicator, Simard has given a Ted Talk and has a book, “Finding the Mother Tree,” coming out in 2020.