Pollard Pruning & Sharing with the Minnesota Zoo

September 03, 2024

This article is part of the Forest Scene newsletter, Issue 31.

A beaver on a rock near water holds a willow branch in its mouth and paws.
A beaver enjoying a willow branch pruned by Dan Gjertson. Photo by Kelly Kappento.

Did you know beavers, porcupines, tapirs, and forestry folk share something in common? Turns out, we all love a good tree branch!

Luckily, the Urban Forestry Outreach and Research (UFOR) team has been able to put this information to good use. For the past two years, they've provided the Minnesota Zoo with tree trimmings for animal habitats. It's all thanks to the decision to pollard prune a willow tree in their nursery on the UMN-Twin Cities campus in St. Paul.

Last March, Dan Gjertson, UFOR arboriculture program coordinator and educator, pruned a truck-bed full of willow branches for the this purpose. As a thanks, Minnesota Zoo Animal Nutritionist Kelly Kappento shared photos of the branches placed in the beaver habitat and being enjoyed by its occupants. 

What is pollard pruning? 

A man, shown from behind, stands atop a bare willow tree. He is at work pruning it.
Dan Gjertson of UFOR pollard prunes a willow tree in the
UFOR nursery. Photo by Theo Keenen. 

Because willow trees can become quite large and sprawling, and are prone to shedding limbs due to their weak-wooded nature, arborists in urban spaces may want to limit their growth. On the UMN campus in St. Paul, UFOR’s willow plantings are adjacent to a parking area, where dropped limbs could hurt people and vehicles. In this case, pollard pruning, a common European practice, helps to prevent future disasters.

Pollarding is done during dormancy. It involves removing every shoot from the tree’s scaffold limbs at the main stem or trunk, thus maintaining the tree’s size and shape while also creating a unique sculptural appearance. This pruning practice should be done regularly, about every 1 - 2 years, depending on the tree species and growth rate.

Close-up of a willow's main stem with all of the scaffold limbs removed.
Pollard pruning involves removing all shoots from the scaffold limbs directly at the trunk. Photo by Theo Keenen. 
Cover of Forest Scene newsletter.

The Forest Scene newsletter is published biannually in the spring and fall, featuring stories and updates from the Department of Forest Resources. Read Issue 31 (2024):