In her forties, Dr. Beresford-Kroeger turned to writing, though it would take a decade to find a publisher for her first manuscript. She has since published eight books, at least a couple of them Canadian best sellers. One was about holistic gardening, another about living a pared-down life. But her main focus was the importance of trees.
She wrote about the irreplaceability of the boreal forest, which principally spans eight countries, and “oxygenates the atmosphere under the toughest conditions imaginable for any plant.” She introduced her “bioplan”: If everyone on earth planted six native trees over six years, she says it could help to mitigate climate change. She wrote about how a trip to the forest can bolster immune systems, ward off viral infections and disease, even cancer, and drive down blood pressure.
There have been skeptics. One publisher admonished her for being a scientist who described landscapes as sacred, she said. The head of a foundation, while introducing her following a screening of “Call of the Forest,” a documentary about her life, let slip that he didn’t believe a word of what she said.
Bill Libby, an emeritus professor of forest genetics at the University of California, Berkeley, said he initially had reservations when Dr. Beresford-Kroeger offered a biological explanation for why he felt so good after walking through redwood groves. She attributed his sense of well-being to fine particles, or aerosols, given off by the trees.
“She said the aerosoles go up my nose and that’s what makes me feel good,” Dr. Libby said.
Outside research has supported some of those claims. Studies led by Dr. Qi Ling, a physician who coedited a book for which Dr. Beresford-Kroeger was a contributor, found visits to forests, or forest bathing, lessened stress and activated cancer-fighting cells. A 2021 study from Italy suggested that lower rates of Covid-19 deaths in forested areas of the country were linked in part to immunity-boosting aerosols from the region’s trees and plants.
“I was laughed at until fairly recently,” Dr. Beresford-Kroeger said, her Irish accent still strong. “People all of a sudden seem to be waking up.”
Nowadays, Dr. Beresford-Kroeger is in great demand, a shift she attributes to mounting fears about the environment and a hunger for solutions.