Deer Impact Toolbox – Helping Understand and Address Deer Impacts on Indiana Woodlands

By Jarred Brooke, Lenny Farlee, Elizabeth Jackson, Mike Jenkins, Caleb Redick, and Richard Sample

When deer are overabundant, they negatively impact woodlands and forests in Indiana. Have you heard this statement before? Are deer having a negative impact on your woodland? How do you know? Can you identify and measure the effect? If the impact is occurring, what tools are best suited to address the impact?

A new set of resources from Purdue University Forestry and Natural Resources Extension and The Nature Conservancy Indiana aims to help landowners and forest managers answer these questions to help them address deer impacts on Hoosier woodlands and forests.

What impacts do deer have on Indiana woodlands?

White-tailed deer are selective in what they eat—favoring certain plants over others and even certain parts of plants (young tender stems). It’s this selective nature that allows deer to shape the plant communities of a forest. When deer are in balance with their habitat, their browsing can positively impact the plant diversity and health of our woodlands. But, when deer numbers exceed what a woodland can support, those impacts may become harmful for both the deer and the forest. And when left unchecked for years, these impacts can have long-lasting or “legacy” effects.

Common problems caused by white-tailed deer overabundance can be summed up into the following categories:

•   Change in plant or wildlife diversity - Overbrowsing of plants favored by deer can reduce important native plants and allow less preferred species to flourish. Some native species like trillium may be eliminated from a woodland because of deer browse.
•   Increase in invasive plants - Overbrowsing of native plants creates room for invasive plants to thrive and spread, resulting in a woodland with a worsened invasive species problem. Invasive species like garlic mustard and Japanese stiltgrass are unpalatable to deer and thrive when deer overbrowse native plants.
•   Reduction in tree regeneration and growth - Overbrowsing from deer affects many young trees and shrubs in a forest. When browsed repeatedly, young tree seedlings may never grow taller than a deer can reach or can be eliminated in a woodland. By selectively browsing certain tree species – like oak – the diversity of tree regeneration can be reduced.
•   Change in forest structure - Severe overbrowsing can cause structural damage in a forest by eliminating forest layers like the ground cover or understory. This often leads to an open or “park-like” look to the forest understory. Many wildlife species rely upon a dense understory for food and cover; thus, deer overbrowsing can reduce habitat for these other species.

How can the Deer Impact Toolbox help?

The resources within the Deer Impact Toolbox provides woodland owners and managers with the information and capability to begin to address the issues deer may be causing. The resources are based on the latest research from Indiana and other states into deer diets, how deer influence the forest, how to monitor deer impacts, and the best tools to manage deer impacts.

Understand & Identify the Problem

The first step in addressing the issue of deer impacts on your woodlands is to understand the problem. However, it is also essential to understand other factors related to the impact of deer, such as what plants deer select to eat. The publication Understanding White-tailed Deer and Their Impact on Indiana Woodlands provides the necessary information to help you understand & identify the problem with deer impacts.

Monitor the Problem

If you suspect you have an issue with deer impacts, consider monitoring your woodland to get a true sense of the severity of the problem. There are several methods – varying in time and complexity – that can be used to monitor deer impact in your woodland. The Monitoring White-tailed Deer and Their Impacts on Indiana Woodlands publication describes many of these methods. A few methods are also described in a YouTube “How-to” video series.

Manage the Problem

When you understand the severity of the deer impact on your woodland, you can decide how best to address the problem. You have several options for reducing the effects of deer, including hunting, fencing, tree tubes, and habitat modification. These methods are described in the publication Managing White-tailed Deer Impacts on Indiana Woodlands.

You can find out more information about the Deer Impact Toolbox, watch the videos, and download the publications for free by visiting the website: https://extension.purdue.edu/pondwildlife/deer-impact.html

Jarred Brooke (Extension Wildlife Specialist, Purdue University), Lenny Farlee (Extension Forester, Hardwood Tree Improvement and Regeneration Center at Purdue University), Elizabeth Jackson (Engagement Specialist for the Hardwood Tree Improvement & Regeneration Center, Executive Director of the Indiana Forestry & Woodland Owners Association, and the Executive Director of the Walnut Council), Mike Jenkins (Professor of Forest Ecology in the Department of Forestry and Natural Resources at Purdue University), Caleb Redick (Research Assistant, Purdue University), and Richard Sample (Ecologist, US Forest Service).