A third of the recently burned forests in the American West will never regenerate, according to research led by Colorado State University foresters and published in the journal Ecology Letters.
“In many places, forests are not coming back after fires,” says Camille Stevens-Rumann, assistant professor in the Department of Forest and Rangeland Stewardship at CSU.
When forestry scientists studied burned forests in Colorado, Wyoming, Washington, Idaho, and Montana, they found no seedlings—none, zero—in one-third of all the sites. These areas will most likely not return as forests, but as shrublands, a consequence of climate change. These forests were too dry to begin with and their fires burned too hot, which killed not only their trees but their ability to grow new trees.
Healthy aspens growing alongside locusts on our ridge four years after the East Peak Fire of 2013.
A three-year-old seedling planted on the burned ridge is surrounded by wildflowers and downed trees.
Shrubs and weeds are replacing centuries-old trees.
Our ridges burned exceptionally hot in the East Peak Fire of 2013, leaving much of our forest with hydrophobic soil–soil that burned so hot it had a waxy cover afterward that repelled water, hence the name, which translates to “afraid of water.” In the years since the fire, we have not seen a single evergreen seedling grow naturally in the burned areas. Aspens have regenerated beautifully, however; their underground root system survived the fire. Starting in 2014, we’ve been replanting with evergreens from the Colorado State Forest Service Seedling Program. Most of the pines, spruces, and firs have survived so far, but some have been crowded out by scrub oaks and locusts. The forest seems naturally inclined to come back as shrubland.
Our lack of tree regeneration is typical of what researchers observed. Across the sites and throughout all the states studied, low–or no–regrowth was the standard.
“We expect variability in how long forests take to recover after wildfires, but the decrease in tree regeneration between the late 20th and early 21st century was pretty striking, and it’s consistent with what we expect to see as climate becomes warmer and drier,” says University of Montana fire ecology Professor Philip Higuera.
“Even if we plant trees in those areas, it’s unlikely to be successful,” says Camille Stevens-Rumann. “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.”
One solution is to plant different types of trees that might be more suited to a hotter and drier environment, she says.
We’ll keep planting and watching on our little plot of land. We know the forest will never again be what it was, but with help we hope it will at least be a forest of some sort.