As of late, sunsets have been spectacularly colorful and horizon lines remain hazy. The air carries a distinct scent many associate with camping — some with fear — and air quality ratings oscillate between moderate to hazardous. Understandably, wildfire is at the top of many folks’ minds.
And it’s no surprise that the Roaring Fork Valley is experiencing a drought. Following a winter of low-precipitation, the water flows have already exhausted the high-elevation snowpack. As of the first week of August, Pitkin and Garfield counties, and most of Eagle County, are considered to be in “D3” drought conditions, according to the National Integrated Drought Information System. The “D3” classification, or “extreme drought,” is due to soil moisture levels and streamflows being between 3% and 5%. Possible impacts include major crop and pasture losses, water shortages and restrictions and, of course, the increased likelihood of wildfire.
The Lee Fire, which started from a lightning strike outside of Meeker on Aug. 2, has continued to expand southward toward Rifle. As of Monday, Aug. 11, it had surpassed 113,000 acres, making it the fifth largest wildfire in state history. Its burn area is roughly equivalent to the stretch of the Roaring Fork Valley — from Glenwood Springs to Aspen.
Lower winds allowed response teams to better protect infrastructure and bolster breaks to bring the large blaze to 7% containment, an improvement from 0% the first week of the blaze. All of the state’s largest wildfires have occurred during major drought years in the last quarter century.
As a result of recent studies, Colorado scientists offer insights into how wildfire ultimately affects ecosystems and vice versa. Some readers may already be aware that quaking aspen trees are a pioneer species. The hardwood tree is particularly well-adapted to colonize disturbed earth, including angled slopes cleared by avalanches or burn scars. The tall, pale-barked trees grow quickly and expand by cloning.
New research by scientists based at Colorado State University (CSU), Western Colorado University (WCU) and the Forest Service indicates that not only do aspen trees move in quickly after wildfires, but aspen stands can act as natural firebreaks to slow or even divert a wildfire. A study, published last month in “Ecological Applications,” analyzed two decades and over 300 wildfires in Southwest Colorado and the Four Corners region.
Aspen trees are considered “high-moisture” hardwoods. The study indicated that forests composed of 25% or more of aspen trees saw fire spread at a third of the rate as forests with aspen trees that make up just 10% or less of its canopy. Additionally, aspen groves at the edge of fires proved to slow or even change the direction of blazes.
“My hope is that this research can help inform fire and fuels management focused on propagation of aspen through prescribed fire [areas],” said Matt Harris of WCU. “In some settings aspen might even be planted around communities to form green fuel breaks for fire protection.”
Another study, led by CSU, arose out of the drought and wildfire-heavy 2020 summer and autumn. Researchers were working on collecting data regarding Ponderosa pine photosynthesis patterns when the site’s air quality plummeted due to wildfire smoke. The photosynthesis test results from a day with heavy smoke were nearly zero — a significant change from the typical data. The Ponderosas appeared to be “holding their breath,” read a write-up for the study in July of last year.
The CSU team began investigating flora response to wildfire smoke and particulate pollution more intentionally. What they have found so far is a pattern. Many species of trees close the pores on their leaves in response to smoke or poor air quality, neither inhaling or exhaling until a few hours after air quality improves. Another hypothesis at work is that the particulates of smoke clog the pores of leaves, especially if the tree doesn’t quickly close those pores when the air quality deteriorates. This research is ongoing as the CSU team seeks insights on the long-term effects of smoke on both individual tree species and the broader ecosystem.
CSU and the Colorado State Forest Service have nearly three-dozen experts regarding various facets of wildfire and its impacts on ecosystems and communities. Highlights of their work can be found on the university’s website at www.source.colostate.edu/wildfire-research