UI Research Targets Glacier Park Tree Mortality
Mapping project looks at damage caused by mountain pine beetle and western spruce budworm.
The outbreaks of mountain pine beetle and western spruce budworm have cut into wide swaths of the forest in and around Montana’s Glacier National Park.
Such damage has been more visible in the park over the past decade — to the tune of about 300,000 acres of damage since 2008 and 160,000 acres damaged in 2012. Associate Professor Jeffrey Hicke in the Department of Geography in the University of Idaho College of Science and master’s student Bingbing Xu are working to map those outbreaks. They also want to document the change and link it with climate data so park managers can better respond to the adapting forest.
“If we develop this climate information, could we forecast for spring what will happen in the future?” Hicke asked. “It’s just another means of documenting a change in the park that could be really important.”
Hicke received a one-year, $24,000 grant from the Glacier National Park Conservancy to document changes in the park’s forest. Richard Menicke at Glacier National Park reached out to Hicke after noticing trees close to the road and in hiking areas of the park that are continuing to defoliate and die.
“The trees will turn noticeably gray,” he said. “After a few years of leaf defoliation, they will be killed.”
Xu, who is also completing the work as part of a master’s thesis in environmental science from the College of Natural Resources, is inspecting U.S. Forest Service aerial detection survey data and spatial characteristics as part of her analysis during the 2017-18 academic year. Xu describes the data as “a whole bunch of polygons,” each with information associated with tree defoliation and mortality.
The data, which goes back to the 1980s, will include surveys from the 2017 summer season. Late-summer fires in and around Glacier National Park will not have an effect on the research.
“I can tell where the trees are dying and where they are being hurt by the defoliators,” Xu said. “With the high-spatial resolution data image, I can tell some area has higher severity.”
In addition, Xu is marking areas of the park officials want to pay more attention to, including old-growth forest. The updated vegetation map and GIS data will provide a baseline for other research and could help identify tree mortality or defoliations areas in other parts of Western North America.
The aerial detection survey data contains information about several different kinds of disturbances – including from the mountain pine beetle and western spruce budworm, Xu said. Glacier officials have seen a fair amount of disturbance throughout the forest, but the compiled data should help pinpoint it and determine exactly which disturbance is affecting certain areas of the park.
“I want to help the park people help manage the trees in a more effective manner,” Xu said.
Hicke and Xu went to Glacier in May as a springboard to the study, though much of the work is being completed in Moscow using the remote sensing images.
The biggest disturbance, they believe, comes from western spruce budworm that feed on the needles of certain trees. Reports have shown that approximately 160,000 acres of park trees were damaged in 2012 and 80,000 acres in 2011, the most severe years for Glacier tree mortality since 2004.
“Sometimes it’s just cyclical,” but Hicke wants to identify what may be causing the latest outbreaks. He also wants to determine if the climate has become more suitable for such flare-ups.
Tree mortality is an emerging issue in Glacier, so Hicke’s research could be even more important about a decade down the road. He is hypothesizing that drought has facilitated outbreaks of the budworm, but the mapping should help assess how and if drought has played a role in the budworm’s work.
Xu said defoliation can be hard to work with because researchers cannot find solid evidence of its presence out in the field alongside other tree killers, and previously defoliated trees might be able to recover once the bugs are removed. Still, there are hosts of trees in the park that are already dead from insects, fire and other factors.
The climate data mapping project should help Hicke, Xu and Glacier watchers better understand the situation.
“We’re definitely trying to help the park,” Xu said. “We’re trying to use the climate data and the (aerial detection survey) data to determine what kind of climate might cause a large-scale insect outbreak.”
Their analysis will have a valuable application for park managers, who will be able to use the UI data alongside previous research to determine which weather patterns lead to future insect outbreaks. That will allow the park to respond proactively when they see certain defoliation signs.
“Say, for example, we find a certain climate condition that appears before an outbreak,” Xu said, “we can give them a probability forecast specific to park climate conditions.”