CSU study finds link between climate change, reduced forest resilience

A new Colorado State University-led study unearthed unhappy news for the resilience of Rocky Mountain forests.

The study examined nearly 1,500 sites in five states — Colorado, Wyoming, Washington, Idaho and Montana — and found a link between Earth's changing climate and significant decreases in post-fire tree regeneration, according to a Colorado State University press release. Regeneration is an important factor for forest health.

Researchers measured more than 63,000 seedlings in a region where 52 wildfires have burned during the past 30 years. They found decreases in regeneration after early 21st century wildfires, when conditions were hotter and drier than in previous years.

“We often talk about climate change and how it will affect us in the future, but the truth is we are already seeing those changes,” said Camille Stevens-Rumann, assistant professor in the Department of Forest and Rangeland Stewardship at CSU, in the press release. “Disturbances like wildfires are a catalyst for change. In many places, forests are not coming back after fires.”

“What we’ve found is dramatic, even in the relatively short 23-year study period,” she added.

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The results of the study mean it could take forests longer to return after they're destroyed by wildfires, if they return at all, according to the press release. Sites that saw the least regeneration were also the warmest and driest sites, where fires burned especially severely. 

“Even if we plant trees in those areas, it’s unlikely to be successful,” Stevens-Rumann said in the release. “We need to start expecting that these landscapes aren't going to look the same in the future, whether it's reduced density of trees or no longer a forest.”

Forest fire danger and reforestation are topics of increased concern across the West. In Colorado alone, an estimated 834 million dead trees line the state's 24.4 million forested acres. The combination of wildfires and insect infestations have led to a reality where 1 in 15 standing trees in Colorado's forests is dead.

Since 1971, Colorado's 10 largest wildfires in terms of acres burned have all occurred after 2000, according to the Denver Post.

Read more about CSU the study at https://tinyurl.com/y7wyenwq.

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Colorado forests by the numbers

Dead standing trees: 834 million on “true forestland” — parcels 1 acre or larger with at least 10 percent tree cover

Increase in dead standing trees between 2010 and 2016: 30 percent

Live trees: 11.67 billion on true forestland

Forested acres in Colorado: 24.4 million

Acres infested by mountain pine beetle and spruce beetle, 1996-2016: More than 5 million

Source: Colorado State Forest Service