SEELEY LAKE – In the deep shade of the Lolo National Forest, the rotting stumps of old-growth pine and larch trees are a tell-tale sign of how things were.
The thick rejuvenation of Douglas fir may be an indication of things to come, and Andrew Larson, an assistant professor of forest ecology in the University of Montana’s College of Forestry and Conservation, isn’t pleased.
“If you walk around in here, most of the stumps will be pine and larch,” Larson said Friday while fending off mosquitoes. “The early logging that went on in here decades ago preferentially removed the large-diameter pine and larch trees.”
Past logging efforts and a long history of fire suppression have left this patch of the Lolo forest in an undesirable state.
As Larson walks below the bows and shuffles through young stands of Douglas fir, he sees the potential for catastrophic fires and the eventual loss of plant diversity.
Students from UM are several days into a study to sample this forest, recording species composition, tree height and canopy structure, among other things.
The study is one of several taking place ahead of forest treatment projects planned across the Southwestern Crown of the Continent, an area spanning 1.5 million acres on three national forests, including the Flathead, Lolo and Helena.
“This treatment here on the Lolo is going to shift the relative species composition by favoring the large trees and breaking up the fuel continuity,” Larson said. “What that’s going to do, functionally, is reduce the continuity of the canopy fuels.”
The forest here is thick, the shade deep and pure. Lichen clings to the low-hanging bows and small trees grow in dense patches below old growth.
The current density has set the forest on a path where shade-tolerant trees, such as Douglas fir, will slowly increase their dominance over time.
Growing at a similar rate and height, Larson said, they pose a threat to plant diversity and could leave the forest prone to large-scale epidemics and catastrophic fires.
“Fires are going to happen,” Larson said. “When a fire does get started, we want it to burn in a way that can be managed and controlled so that it doesn’t completely replace the forest and result in complete mortality.”
Forest restoration has been a top Forest Service priority since 2009 when the Secretary of Agriculture announced a new national vision for the nation’s forest.
That same year, Congress passed the Collaborative Forest Landscape Restoration Program, funding large-scale treatment efforts as a driving principle in forest management.
The new approach gave the College of Forestry at UM the opportunity to measure the success of restoration efforts by recording conditions before and after treatment.
“We have 10 plots, enough for a good sample,” Larson said. “They’re chosen randomly to eliminate bias. We’ll come back in and compare the results when the treatment project is finished.”
UM’s efforts here on the Lolo follow a similar study completed on the Flathead National Forest in the Meadow Smith old-growth restoration area.
Larson and UM associate professor Chris Keyes, along with UM graduate student Kyle Stover, created tree maps and applied spatial statistics to demonstrate how thinning efforts changed growth patterns.
They also compared maps of restored forests to those of historic forests to evaluate how effective the treatment was at restoring old-growth conditions.
“Up on the Flathead, there were a lot of big, old-growth trees to work with,” Larson said. “They could strategically remove the smaller trees and put things back into a condition of resilience and sustainability.”
The results of the Flathead study were published this month in the Canadian Journal of Forest Research. The first of its kind, the study showed that certain treatments were successful in restoring the spatial elements of old-growth forests.
“There’s very little information on that particular topic out there,” said Larson. “We can’t detect any difference in the patterning that was left after treatment. It’s the first quantitative characterization of old-growth spatial structure in the Northern Rockies.”
Larson said the Lolo study would look for similar treatment results. Another pre-treatment study also is planned this summer for the Lincoln District of the Helena National Forest.
“The Flathead was a good place to start, but this area has a history of more intensive logging,” Larson said of the Lolo. “You don’t have as much residual structure in the forest to work with. It’s about crafting or shifting how the forest is going to develop over time.”