By Gary Roloff

ESCANABA —

Logging debris (slash) left on the ground can be ugly but, in some cases, may serve a valuable purpose. Many areas of Michigan are afflicted with a lack of adequate tree regeneration due to deer browsing. High slash piles may help protect those vulnerable seedlings and saplings.

For decades, foresters were encouraged to leave clean sites and use all merchantable material during timber harvest operations. A massive study on northern hardwood forest regeneration may change that practice.

Researchers have begun a large experiment in Michigan to test different ways to regenerate tree species that deer like to browse. On some sites, regeneration of yellow birch, basswood, and sugar maple has been nearly absent for decades.

The project adopted two general approaches to encourage recruitment into the overstory. One approach is to flood an area with so much regeneration that enough desired trees make it to the overstory. The other approach is to use logging tops as barriers that restrict deer access.

Admittedly, the result does not look pretty, resulting in a tangle of downed tree tops, but it may offer one solution to help desirable tree species regenerate in areas with heavy deer use.

The study involves 140 30-acres sites ranging from Grayling to the tip of the Keweenaw Peninsula. Half of those sites include the “leave tops” prescription. Loggers were asked to leave tops that were over nine inches in diameter, and then overlay the tops to create a tangle that will, hopefully, deter deer. Unfortunately, these sites are ugly and difficult to walk through, but hold promise for tree regeneration (photo 2).

Research technicians are collecting data on deer behavior on these sites. Although preliminary results suggest success, deer are pretty persistent (Photo 3)! Unless large material is left, the slash may not last long enough for the new trees to grow tall enough to evade the deer. Additionally, deer and hare exclosures were built on 24 leave-top sites. Therefore, we can compare how the tree tops are functioning to an area we know that deer and hare can’t access. We won’t know the official results of all of these treatments until the trees are big enough to release from the deer browse zone (about 10 years for some species). However, the research partners are committed to the long-term monitoring to answer this important question.

Interestingly, research from other parts of the world suggests that tree tops function better at deterring deer when deer predators are in the vicinity. The thought is that predators (like wolves) change deer behavior in that deer avoid dense tangles, presumably because they are more vulnerable to being trapped. Our study will be able to document this effect in that we are recording deer and other wildlife use with remote cameras on our sites.

The “leave top” prescription is ugly, and reduces the amount of merchantable timber produced. However, if successful regeneration of these highly valuable northern hardwood forests is the result, then this is a sound investment. So, the next time you are walking through the Michigan woods and come across a site that looks ugly because of the amount of residual material left, remember that it may be part of this innovative research project to help produce a beautiful northern hardwood forest of the future.

This long-term study is being conducted in cooperation with Michigan State University, the Michigan DNR, the forest products industry, and Safari Club International, Michigan Involvement Committee. For more information, contact Gary Roloff (roloff@msu.edu) or Mike Walters (mwalters@msu.edu).

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As an MSU Extension forester, Bill Cook provides educational programming for the entire Upper Peninsula. His office is located at the MSU Forest Biomass Innovation Center near Escanaba. The Center is the headquarters for three MSU Forestry properties in the U.P., with a combined area of about 8,000 acres.