In an aspen-dominated hardwood forest at the northern tip of the state’s Lower Peninsula, University of Michigan scientists are testing ways to make the region’s forests more resilient to climate change.

About 12,000 mature trees—mostly aspen—are being cut on 77 acres at the U-M Biological Station, a 10,000-acre research and teaching facility just south of the Mackinac Bridge, near the town of Pellston.

The idea of the UMBS Adaptive Aspen Management Experiment is to replace some of the century-old aspen with a mix of tree species and age groups that may be better equipped to handle a warming climate, extreme weather events, and stresses such as insect pests.

The harvesting started in March, paused in May for bird-nesting season and student summer research, and will be completed in September. By the time it’s done, about 200 truckloads of logs will have been hauled to a nearby mill for processing into wood siding and trim for homes.

Cutting some of the mature aspen, which are nearing the end of their lifetime, will stimulate the regrowth of new aspen trees and should boost understory species, as well, said U-M ecologist and biogeochemist Luke Nave, who leads the project.

“We’re reaching a point with our climate where we can’t pretend that it’s not changing. To sit by and do nothing, when we have a forest that is vulnerable to climate change, would be irresponsible,” he said.

Nave is standing in front of a tall stack of bigtooth aspen logs ready for transport to the Upper Peninsula mill. Nearby, two large, noisy machines move methodically through the forest, cutting aspen trees into 8-foot, 4-inch logs, then stacking them. Some of the trees are 100 feet tall, with trunks nearly 2 feet in diameter.

Aspen in the Great Lakes region are considered “climate change losers,” according to Nave, and are not expected to fare well as the region’s climate continues to warm in the coming decades. Stands dominated by a single species and containing trees of a uniform age and canopy height may be especially vulnerable.

“I’m not a finance guy, but you can think of forest management in terms of investment strategies. You don’t put all your investments in one place. You try to diversify, because it protects you against risk,” said Nave, an associate research scientist at the Biological Station and in the U-M Department of Ecology and Evolutionary Biology.

“So, if you have different tree species arrayed in different age classes across the forest, that’s a diversified investment strategy that increases your capacity to respond to climate warming, drought and severe weather events.”

The U-M aspen management project is a formal demonstration site of the Northwoods Climate Change Response Framework, a regional collaboration among scientists, land managers and private landowners to advance climate change adaptation efforts.

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