A male deer eating leaves from a tree

Our Wisconsin Understory is a new collaborative program that teaches citizens how to use the Twig-Age method to collect and submit data. At this point, we are testing out procedures and this website. You can help us! Please try out the site, the Twig-Age method, and submitting data. Then, share your experiences and suggestions with us via understory@botany.wisc.edu. The data that you provide us with goes towards more accurately measuring the impact that deer populations have on our state’s forests. This gives us important information on how to better manage deer populations and the overall health of forests in Wisconsin.

What is an understory?

An understory is the part of the forest that is below the trees and near to the ground. It is often made up of shrubs, wildflowers, weeds, saplings (baby trees), and other small plants. The understory is a very important part of the forest because it provides food and habitat for animals, as well as a space for young trees to grow and eventually replace old trees.

How do deer affect the understory?

Deer are herbivores, which means they need to eat lots of plants to survive. They only eat (or “browse”) plants that they can reach, such as the short tree saplings that grow in the understory of forests. If there are too many deer in a forest, they will begin to over-browse on these tree saplings, keeping them at a short height. This makes it difficult for new trees to grow and eventually replace old ones. Deer also act as a host for ticks, including deer ticks which can carry Lyme disease.

A yellow birch tree sapling that has been browsed by deer
A Yellow Birch sapling that has been browsed by a deer (where twigs are chopped off).

Click to learn more about deer abundance

Click to learn more about ticks and Lyme Disease

What is the Twig-Age method?

This is a very simple data collection method created by Dr. Donald Waller of the University of Wisconsin-Madison. It involves looking at the most recent year’s growth on a tree sapling’s twig, and then using “scars” on the twig to count how many years it has been growing. This allows us to see how many years this twig has been able to grow without being browsed by a deer. Click here to learn more about the Twig-Age method. To learn how to use the Twig-Age method and collect data, go to our Get Started menu.