Deer exclosures

Keeping deer away from nature’s salad bar

Minnetonka residents are well aware of the city’s substantial deer population, and those deer find native wildflowers, small trees, and shrubs quite tasty. While deer munch on the woody plants from above, rodents are nibbling on the bark and cambium from below. Animal browsing makes plant re-establishment a challenge in city restoration projects.

Now that many acres in the Minnetonka Park system have had buckthorn and other invasive plant species removed, a test plot study has been established to monitor the ability of selected native plants to become re-established in areas previously occupied by non-native, invasive plants.

In 2006 five native shrub species indigenous to the oak woodlands of Minnetonka were planted in the test plots. Bare root and potted nannyberry, gray dogwood, choke cherry, hazelnut, and pagoda dogwood were planted in 80 percent of the plots. The other 20 percent of plots had no plantings, so that natural regeneration can be observed.

To protect these native species while they regenerate, 20 deer exclosures have been built in three natural-area parks: Lone Lake, Big Willow, and Victoria-Evergreen. A deer exclosure is just the opposite of an enclosure—designed to keep the deer out rather than in. These structures are 900 square feet, constructed with posts and fenced with synthetic black mesh. For every four deer exclosures, one open plot exists to allow comparison of plantings inside and outside of protected areas. Because the deer threat in Minnetonka isn’t going away, plants inside and outside of the deer exclosures will be observed for many years. However, replanting in parks will not wait for years—as funding and volunteer time allow, new native plantings will be installed in active restoration areas. A variety of plant-protection materials will be used around the new plants, including fencing rings, hardware cloth, and tube tree shelters.

If you would like to volunteer to help with native plant restoration, call Janet Van Sloun Larson at 952.988.8423 or at jrlarson@eminnetonka.com.

More about native plant revegetation

  • Native plant populations have dropped to an alarmingly low level in the understory of most suburban parks, and have nearly disappeared from many others.
  • In addition to munching on garden and woodland plants, deer also rub the velvet from their antlers on sapling trees, causing damage to the vascular systems directly under the bark and sometime killing the tree.
  • Ten re-vegetation plots have been set up at both Big Willow and Lone Lake parks, while Victoria-Evergreen has five plots. Twenty of these plots are fenced exclosures.
  • Plot locations within the parks were chosen to take advantage of as many site variations as possible. Tree canopy type and density, ground slope, directional exposure, and ground cover composition differ on each site.