Ungulate browsing affects recovery of forests impacted by eastern spruce budworm

Monday, November 14, 2022

12:06 PM – 12:18 PM PT

Location: Vancouver Convention Centre, Meeting Room 206

Presenting Author(s)

JR

Jessica M. Rootes

Graduate Student
University of Minnesota
Saint Paul, Minnesota

Co-Author(s)

BA

Brian Aukema

Professor
University of Minnesota
Saint Paul, Minnesota

A native defoliator, the eastern spruce budworm (Choristoneura fumiferana), undergoes cyclical outbreaks every 35 to 40 years that can last up to 10 years. During these outbreaks, 70% of balsam fir trees (Abies balsamea) and 40% of white spruce trees (Picea glauca) can experience mortality resulting in canopy gaps within the forest. Post outbreak, a combination of hardwoods and conifers regenerates but may be impeded by browsing by large herbivores. We compared locations in Northern Minnesota and Isle Royale National Park in Lake Superior to study how ungulates impact regeneration within spruce budworm-created forest gaps. Isle Royale is a unique international bioreserve in which moose populations are more dense than mainland populations. We found that high moose numbers resulted in undesirable defoliation levels of regenerating trees on the island due to over browsing. This study presents a unique opportunity to understand how effects from budworm outbreaks cascade through forest ecosystems.