Identifying Plant Compounds in Northern White Cedar that Protect Against White-Tailed Deer Browse

Research Issue

[photo:] Northern white cedar seedlings in the greenhouse that are grown from cones collected across 3 locations where presence and absence of deer browsing occurred. Photo by Ryan Vinhal, USDA Forest Service.Northern white cedar (Thuja occidentalis L.), also known as arborvitae, is an important tree species notable for its use in agroforestry windbreak systems. Difficulties in natural regeneration of northern white cedar in forested landscapes have caused concerns for the long-term sustainability of the species.

White-tailed deer (Odocoileus virginianus Zimmerman) have been identified as one probable cause of disrupted cedar regeneration due to 1) their use of northern white cedar as a preferred winter browse species and, relatedly, 2) their abundance across northern white cedar’s range. Heavy browsing by white-tailed deer results in white cedar damage and disrupts the natural growth and regeneration of cedar seedlings. Interestingly, some cedar individuals are preferentially browsed by white-tailed deer, while other nearby trees are left untouched.

Knowledge about the interaction between white-tailed deer and northern white cedar is limited, especially regarding the reasons for preferential browsing among cedar individuals. To promote northern white cedar growth and prevent future decline, it is important to identify factors influencing white-tailed deer browse on northern white cedar.

Our Research

[photo:] Outplanting at an eastern Wisconsin agroforestry phytoremediation buffer system of cedar grown in the greenhouse from seeds collected across 3 study locations. Plantings will be used for field-based monitoring of deer browse. Photo by Brent DeBauche, University of Missouri.This research examines the role of plant-produced chemical compounds, known as phytochemicals, in affecting deer browse on northern white cedar. Volatile chemical compounds produced by plants can act as defense mechanisms against browse by herbivores. In this study, we are testing for differences in phytochemicals between white cedar trees from the same stand that have and have not been browsed by white-tailed deer, specifically by comparing the volatile chemical composition of leaf material among trees using modern bioanalytical and metabolomic approaches. By combining data obtained using innovative lab techniques, controlled feeding studies with captive deer, and field trials, this research will help to better understand and identify the role of phytochemicals in deer browse resistance. Such information can be used to improve northern white cedar growth and establishment potential, including for agroforestry applications.

In addition, we planted seedling offspring of study trees underneath poplar in agroforestry phytoremediation buffer systems (link) from our regional phytotechnologies testing network in the Great Lakes Basin, funded by the Great Lakes Restoration Initiative (GLRI). This anthropogenic successional project aims to identify tree species that can be underplanted and succeed poplar plantings once phytoremediation has completed and the trees have been harvested and removed from the site.  

Expected Outcomes

The primary objective of this study is to identify chemical compounds within northern white cedar that are responsible for plant defense against herbivory by white-tailed deer. This research will advance the understanding of the role that phytochemicals play in the interaction between these two species and further, will help identify the potential for these chemicals to be used in natural-based deer repellents. This information will be important for researchers, land managers, foresters, and nursery managers who are seeking to improve natural regeneration of cedar within forests, or to select genotypes with increased resistance to deer browse for multiple ends uses, including agroforestry and phytotechnologies.

Research Results

Vinhal, R.; Lin, C-H. 2021; Zalesny, R.S. Jr. Identifying chemical compounds responsible for deer browse resistance in northern white cedar. In: University of Missouri Center for Agroforestry (UMCA) Annual Research Review; University of Missouri – Columbia; January 27, 2021;  Onilne at 4:05 (ORAL)

Research Participants

Principal Investigators

  • Ryan Vinhal, USDA Forest Service, Northern Research Station- Biological Science Technician; University of Missouri – Columbia- Master’s Student
  • Chung-Ho Lin, University of Missouri – Columbia, Center for Agroforestry, Columbia, MO
  • Ronald S. Zalesny Jr., USDA Forest Service, Northern Research Station- Supervisory Research Plant Geneticist


  • Last modified: April 22, 2021