Large, severe fires in the West followed by increasing drought conditions as the planet warms are leading to lower tree densities and increased patchiness in high-elevation forests, according to a new study involving the University of Colorado Boulder.
For the study the team looked at nearly 200 subalpine forest plots that had undergone severe fires between 1994 and 2003 in and around Yellowstone National Park and Glacier National Park in Wyoming and Montana, said CU-Boulder postdoctoral researcher Brian Harvey.
Subalpine forest regions in the West are the dense forests just downslope from the alpine tundra, said Harvey of CU-Boulder's geography department who led the study while a graduate student at the University of Wisconsin-Madison.
The researchers found that the rate of post-fire tree seedling establishment decreased substantially with greater post-fire drought severity. Seedling establishment also decreased when the seed sources were at greater distances from the edge of burn patches, he said.
The team also found evidence that tree species from warmer and drier climates at lower elevations may colonize burned areas in subalpine forests as temperatures climb, but at rates lower than the decrease of current subalpine tree species, Harvey said.
"This study is a crystal ball of sorts that helps us to see what forest recovery may look like in the future following severe fires," he said. "These forests are well adapted to severe fires, but the net result of larger fires and warmer temperatures will likely be a decrease in tree density, a reduction in forest extent, and more forest patchiness in high-elevation areas."
A paper on the subject was published online in Global Ecology and Biogeography. Co-authors on the study include biologist Daniel Donato of the Washington State Department of Natural Resources in Olympia and Professor Monica Turner of the University of Wisconsin-Madison.
The team measured tree species, numbers, sizes and ages of post-fire tree seedlings in the high-altitude forest plots. They also measured the distance between each plot -- which were roughly 100 feet in diameter -- to the nearest tree seed sources, as well as charting drought severity in the three years following severe fires.
Each study plot was located in areas of severe wildfires that burned in 1994, 1999, 2000 and 2003, times of widespread fire across the Northern Rockies, said Harvey.
"Over the next century, large fire years followed by droughts at least as severe as those seen in recent decades will likely become a more regular occurrence in the U.S. Northern Rockies," the authors wrote in Global Ecology and Biogeography.
Temperatures in the West have risen 2 to 3 degrees Fahrenheit in recent decades, which climate scientists attribute in large part to rising greenhouse gases in Earth's atmosphere as a result of human activity.
Seedlings of Engelmann spruce and subalpine fir, two common subalpine trees, decreased substantially in high elevations when coupled with fire and drought. But a third major subalpine species, lodgepole pine, was less affected, in part because of the abundant seeds stored in its cones that are released after fire events, said Harvey.
High-elevation forests in the western U.S. also can host Douglas fir, quaking aspen, western larch and whitebark pine. Both Yellowstone and Glacier have large amounts of of federally protected land, much of it wilderness, that allows natural tree regeneration after fires and makes the subalpine zone a living lab of sorts for researchers, he said.
"Data showing how forests may or may not recover following future fires in a warmer climate is extremely hard to get," said Harvey. "Our approach was to look at recent fires that were followed by a range of climate conditions, with the warmer/dryer scenario the most likely window into what we might expect in the future.
"When we were collecting data for this study, we essentially were walking around on the front lines of climate change," said Harvey.
The study was funded in part by the U.S. Joint Fire Science Program and the National Park Service. The study involved undergraduates, graduate students, postdoctoral researchers and faculty.
Brian Harvey, 650-521-1988
Jim Scott, CU-Boulder media relations, 303-492-3114
Brian Harvet | EurekAlert!
Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research