Inside the Source: Deer vs. Seedlings in Michigan's Northern Hardwoods

March 18, 2020

Below is an excerpt of an article featured in The Forestry Source, March 2020. To learn more about The Forestry Source, click here. To learn more about SAF membership, click here.

Deer vs. Seedlings: A Study in Michigan’s Northern Hardwoods Seeks Answers
By Steve Wilent

For most foresters, establishing 140 plots isn’t unusual, but setting up that many 30-acre plots across half a state is something most of us will never do. Researchers in Michigan, seeking answers to the devastation wrought by hungry deer on the state’s forests, established 140 30-acre plots designed to help them learn whether new silvicultural techniques might help minimize the ungulates’ impact upon hardwood regeneration. With nearly two million white-tailed deer in the state, valuable hardwoods such as sugar maple have difficulty regenerating: The deer eat many seedlings before they grow to a height beyond a deer’s reach.

Single-tree and small-group selection silviculture is the norm across about 12,000,000 acres of northern hardwoods in Michigan. Typically, stands are entered every 10 to 15 years, and about a quarter of the volume in each stand is removed, predominantly by removing large trees and thinning out some of the smaller trees.

“In the gaps left after the larger trees are harvested, the expectation is that natural regeneration of sugar maple and other shade-tolerant hardwoods occurs,” said Michael B. Walters, an associate professor of forest ecology in the Department of Forestry at Michigan State University (MSU). “However, the pattern over millions of acres of northern hardwoods in the Great Lakes region is quite a bit different than that. Instead of having abundant sugar maple regeneration, which is of high economic and ecological value, harvest gaps have no regeneration in them at all, or have dense or at least well-stocked regeneration in the sapling class of beech and/or ironwood. Circumstantial evidence is that deer are causing that.”

Sugar maple, a preferred species, is the dominant tree in most of the study area.

Deer aren’t the only factor: A lack of forest-floor disturbance, for example, makes it difficult or impossible for small-seeded tree species such as birch to reproduce.

Dubbed the “big northern hardwoods study,” plots totaling 4,000 acres were placed across the state’s Upper Peninsula and northern Lower Peninsula by Walters, who has researched the deer-browsing problem over the last 20 years, and his colleagues. They will monitor the sites over 10 years. A paper in the February 2020 edition of the Journal of Forestry, “Rethinking Northern Hardwood Forest Management Paradigms with Silvicultural Systems Research: Research–Management Partnerships Ensure Relevance and Application,” by Michael B. Walters, et al., describes the study in detail. 

To learn more about the study, I talked with Walters and Michael Donovan, a natural resources manager in the Wildlife Division at the Michigan Department of Natural Resources (DNR); Evan Farinosi, a doctoral student in MSU’s Department of Forestry; Jason Hartman, a silviculturist in DNR’s Forest Resources Division; and Gary Roloff, a professor in the Department of Fisheries and Wildlife at MSU.

Click here to download the full article.