New research from the UBC-based Mother Tree Project is shedding light on how forests respond to harvesting and climate stress, including practices aimed at reducing wildfire risk.
Dr. Suzanne Simard, a forest ecologist who leads the project, has spent more than a decade studying how Douglas fir forests recover after disturbance. The Mother Tree Project has produced multiple peer-reviewed studies, with more findings to come as the long-term research continues. Dr. Simard’s new book, When the Forest Breathes , builds on those findings and outlines a different approach to forest stewardship.
In this Q&A, she discusses what the research shows, what may need to change in B.C.’s forests, and the ideas behind her new book, which she will launch at a public Earth Day event April 22 at UBC’s Chan Centre for the Performing Arts.
Many communities are thinning forests to reduce wildfire risk, often without clear evidence of the ecological trade-offs. We studied a community forest near Whistler with partners from the Lil’wat Nation and Squamish Nation to better understand those impacts.
In younger forests, careful thinning kept overall carbon levels stable in the short term and increased plant diversity, tripling the number of herb species. But it also simplified the forest structure and increased the dominance of Douglas fir. Forests made up mostly of one species are more vulnerable to pests, disease and climate stress.
More intensive clearing had much larger effects. In nearby old-growth areas, it reduced total ecosystem carbon by 42 per cent, with above-ground carbon five times lower than in intact forests.
We compare different harvesting approaches in Douglas fir forests across B.C.’s Interior, alongside uncut areas. We track new tree growth, biodiversity and how much carbon is stored in trees and soils.
One clear pattern is that intact and lightly harvested forests store far more carbon. They also support stronger recovery over time.
We’ve also found that leaving mature trees standing—the overstory—helps forests regenerate and adapt, especially as drought becomes more common. These trees support native plant communities and reduce the spread of invasive species. By contrast, more intensive approaches can remove up to half of the carbon stored in a forest ecosystem.
Indigenous peoples have cared for these forests for thousands of years through systems grounded in long-term responsibility and close observation. In this work, First Nations partners are involved from the beginning—helping shape research questions, study design and how results are interpreted and applied.
Our research shows that more intensive approaches can disrupt the systems forests rely on to recover. Retaining mature trees and protecting soils, biodiversity and underground fungal networks are all critical, especially as climate extremes increase. It also points to the need to protect remaining intact old-growth and primary forests, which play an outsized role in storing carbon and supporting biodiversity. Equally important, we should ensure that Indigenous leadership is central to how forests are managed.
When the Forest Breathes brings together findings from the Mother Tree Project with what we’re continuing to learn about how forests function as living, connected systems. It’s also about shifting how we see forests, from resources to be extracted, to communities that sustain climate, biodiversity and human well-being.
The Earth Day event brings together science, music, Indigenous performance and legal perspectives. Why does it matter to bring these voices together now?
Science alone doesn’t always change how people relate to forests. Bringing together science, Indigenous leadership, art and music can create a deeper connection and a broader understanding of what’s at stake. It helps people see forests not just as timber, but as living systems that support communities, culture and climate.
Interview language(s): English (Dr. Simard, collaborator Dr. Teresa Ryan)
For more information about the Earth Day event, visit forestry.ubc.ca/events/ubc-celebrates-earth-day-with-suzanne-simard .
For media inquiries please contact charlotte.fisher@ubc.ca or lou.bosshart@ubc.ca For operational inquiries regarding the Mother tree project and program, contact stephanie.troughton@ubc.ca
Canadian Journal of Forest Research
Experimental study
Not applicable
Effects of fuel reduction thinning and patch clearcutting on carbon stocks and plant diversity in south coastal rainforests of British Columbia
17-Mar-2026