UI allows the native beaver to gnaw down invasive trees, while saving protected species

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Monday, April 13, 2015
Written by: Wendy Moorehead

Keeping the University of Iowa campus beautiful is a full-time job. Luckily, the UI Landscape Services team gets a little assistance each year in the form of some notoriously busy helpers: the nocturnal, semi-aquatic beaver.

Beavers, a native Iowa species, typically gnaw down trees along the UI campus riverbanks, which is fine for some tree species, but not for others. Instead of stopping the beavers’ behavior, the tree care team decided to work with the beavers’ natural talents. By wrapping valued native and planted trees with protective wire, the invasive and common native species like Boxelder, White Mulberry, Siberian Elm, Willow, Green Ash, and Silver Maple, are left for the beavers to utilize in their underwater homes for food and shelter.

The UI’s protected vistas management strategy, cited as far back as 1996, strives for balance between having some trees along the riverbanks while reducing the number of unsightly invasive and weedy species. This approach opens up vistas all along the Iowa River near the Art Building, Theatre Building, and Hancher Auditorium, while lightening the maintenance workload for the tree care team.

It is true that beavers can be destructive if their work is not redirected; however, under the right circumstances they can be used as an effective, low-cost management tool. Next to humans, no other animal appears to do more to take care of its landscape.

Andy Dahl next to trees showing evidence of beaver gnaw
Andy Dahl removes a plastic bag someone used to try to prevent further beaver damage. Dahl, an arborist with Facilities Management, works to protect certain types of trees from beavers, but for the most part lets them do their thing along the river. Photo by Tim Schoon.

“While there may be a number of trees gnawed off along the riverbanks, the beavers’ work will not kill the tree as the root system is still intact, so the tree typically will resprout. As long as they continue to do this to the invasive species, we don’t have a problem with them. They’re a spoke in the wheel of life as are the trees, as are we," says Andy Dahl, UI arborist. "We’re happy to have them as our partners to manage the riverbanks.”

As the UI continues to recover the campus from the 2008 flood, there is a concerted effort to do even more clearing along the riverbanks. A transformation of the river walk is well underway with the combination of flood-recovered buildings, new sidewalks, new entryways, and the riverbank clearing.

“The flood recovery is helping us to clean up and better celebrate the Iowa River. Those busy beavers are helping to contribute to that effort,” says Don Guckert, associate vice president of Facilities Management.