A University of Montana scientific evaluation of a forest restoration project on the Flathead National Forest in western Montana has found promising early results.
“Our monitoring results from the Meadow Smith old-growth restoration project show that the treatments successfully restored spatial elements of old-growth forests,” said Andrew Larson, a UM assistant professor of forest ecology. Larson is lead author of the most detailed analysis yet of restoration treatment effects on forest spatial patterns. The work was published online July 18 in the Canadian Journal of Forest Research (http://www.nrcresearchpress.com/journal/cjfr).
Larson and his co-authors, former UM graduate student Kyle Stover and UM associate research professor Chris Keyes, created maps of tree locations and then used spatial statistics to show how thinning treatments changed tree patterns. In a second analysis, they compared tree maps from restored forests to tree maps from historical old-growth forests to evaluate how effective the treatments were at restoring old-growth conditions.
The new study looks at forest restoration treatments in the Southwestern Crown Collaborative (SWCC) project area, a 1.5 million acre area spanning the Blackfoot, Clearwater and Swan river valleys that encompasses portions of the Flathead, Helena and Lolo national forests. Restoration work developed through the SWCC is funded by the U.S. Forest Service Collaborative Forest Landscape Restoration Program (CFLRP).
Forest restoration has been a top priority for the Forest Service since 2009, when U.S. Secretary of Agriculture Tom Vilsack announced his national vision for America’s forests and Congress created the CFLRP. Vilsack’s national vision identifies restoration as a driving principle of forest management, and the CFLRP provides additional funding for the Forest Service to implement large restoration projects.
One of the big challenges foresters face is incorporating spatial heterogeneity into forest restoration treatments. Spatial heterogeneity refers to variation in how trees are spaced with respect to each other. Variable tree spacing causes different levels of canopy closure within forests, which regulates important ecological functions.
“You can get an idea of why spatial heterogeneity matters by thinking about the arrangement of furniture in your living room,” Larson said. “Push all of your couches, tables and chairs into the corner, and you won’t be happy with the result. The altered arrangement limits their functionality.”
In forests, dense tree clumps provide hiding cover for wildlife, while openings and areas with widely spaced trees let plenty of sunlight reach the forest floor, helping understory plants flourish and tree seedlings get established. Variable tree spacing also affects wildfire behavior and the spread of insects and diseases from tree to tree.
“While this project successfully restored spatial aspects of old-growth forests, it was largely due to the presence of many live, old ponderosa pine and western larch trees in the project area and their designation for retention in the thinning treatments,” Larson said.
At many sites where restoration is planned, the largest pine and larch trees have been harvested or the pines were killed by beetles. He said restoring spatial heterogeneity at such sites will be much more challenging.
“The clear implication is that foresters will need to directly address spatial patterns in the design and implementation of restoration treatments,” Larson said.
The Meadow Smith project was designed before the Forest Service received funding for SWCC, but it was one of the first forest restoration projects to be implemented in the SWCC project landscape. The monitoring results provide new information for the collaborative and the Forest Service that will help fine-tune future jointly designed restoration projects.
Monitoring of understory plants, surface fuels and large down wood is also under way but was not part of the results published July 18.