In dense forests, tree branches can intercept a significant share of falling snow before it ever reaches the ground.
“When snow is falling, trees can act as an umbrella, and they can prevent the snow from actually reaching the ground, so it never becomes part of the water supply,” said Emily Howe, an aquatic ecologist with The Nature Conservancy and a co-author of the research published in the journal Frontiers in Forests and Global Change.
That snow can then evaporate or melt off the branches, meaning it never contributes to the snowpack that feeds Western waterways.
The study found that thinning overly dense forests — a common strategy used to lower wildfire risk — can allow more snow to reach the forest floor and remain in the mountains longer.
Across much of the West, decades of fire suppression and other land management practices have left many forests denser than they historically were, with tightly packed trees competing for water and sunlight.
Researchers say reducing that density can change how snow behaves on the landscape, sometimes allowing more of it to accumulate on the ground instead of getting caught in the canopy.
The findings suggest wildfire mitigation efforts could have an added benefit for water supplies, particularly in snow-dependent regions of the West.
“Our research just shows that reducing wildfire risk and protecting water resources don't have to be competing goals,” Howe said. “They can be synergistic with one another.”
Snow that stays on the ground longer can melt more gradually in spring, feeding streams and reservoirs that support farms, cities and wildlife habitats downstream.
Even modest changes in forest density, she said, can influence whether snow sticks around to feed rivers and reservoirs or disappears before it ever becomes part of the region’s water supply.
Howe said the research highlights how forest management decisions can ripple beyond wildfire prevention, affecting water systems that millions of people rely on.
This story was produced by the Mountain West News Bureau, a collaboration between KUNR, Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNC in Northern Colorado, KANW in New Mexico, Colorado Public Radio, KJZZ in Arizona and NPR, with additional support from affiliate newsrooms across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting and Eric and Wendy Schmidt.
