• Diana Beresford-Kroeger in her new tree documentary Call of the Forest

    Diana Beresford-Kroeger's documentary Call of the Forest reveals how our health and the health of the Earth depends on the state of our forests. The film's Toronto opening is May 12 and 13. (Photo: TARO PR)

Diana Beresford-Kroeger can trace her profound knowledge of the influence and power of trees back to her childhood in Ireland, and a turn of fate. Orphaned at 11 by a car crash, she was taken in and raised by Irish elders who adhered to the ancient, pre-Magna Carta Celtic Brehon laws. “There,” she says, “I was taught all the laws of the trees, the laws of nature and its medicines.”

That might sound like the start of a movie, but it was a reality that set her on a path that married folk wisdom, spirituality and history with her eventual work as a surgeon, medical biochemist and botanist, producing several books (including the acclaimed The Global Forest and Arboretum Borealis) and, most recently, the documentary Call of the Forest: The Forgotten Wisdom of Trees.

In the film, Beresford-Kroeger (a Fellow of The Royal Canadian Geographical Society) journeys from Canada's boreal ecosystem to the forests of Japan, Ireland and California, drawing together other field-leading tree scientists and revolutionary tree science, foresters and activists working to protect and replant the world's northern forests.

Along the way — and with the help of narrator Gordon Pinsent — she sheds light on everything from modern medicine's reliance on trees for the development of crucial medications to the dependence of all life on Earth on forests — even, amazingly, the species off our coasts. Today, despite the fact that 95 per cent of the world's old-growth forests have been chopped down, trees are the link in a chain that cannot be broken without dire consequences. Of Call of the Forest, environmental scientist and The Nature of Things host David Suzuki has said, “[Trees] are the very foundation of the web of life of which we are a part. In this lovely film, we are shown that we need trees for our physical, social and spiritual well-being.”

It's no wonder, then, that Beresford-Kroeger describes an intact forest as “a mighty act of peace.” And restoring these ecosystems across the world might not be as futile an exercise as you'd think: the “Bioplan for Biodiversity” that concludes the film is Beresford-Kroeger's simple challenge for every person to plant one native tree species in a native space each year. Just by doing this, she calculates, we can start to reverse climate change.

For those of us who can't tell a beech from a birch from a bur oak, the film's associated Find-A-Tree app — which lists native tree species based on your location and lets you explore their characteristics, medicinal and environmental benefits, as well as planting requirements and instructions — is online now and will be available for mobile download later in 2017. “This is a lifetime of work that I have produced here,” says Beresford-Kroeger. “And my lifetime is being given into your hands so you can use it for the benfit of the planet. And I'm very honoured to be able to do that.”

Call of the Forest has been debuting in cities across Canada since March, beating National Film Board box office records along the way. Its next screenings are at the Art Gallery of Ontario in Toronto on May 12 and 13, and Bereford-Kroeger will be on hand for a Q&A after each showing. Click here for ticket information.