The Minnesota Department of Natural Resources (DNR) recently conducted an aerial survey covering over 13.5 million acres. This is part of their annual effort to monitor the health of the state’s forests, with findings detailed in their latest 2025 Forest Health Annual Report.
Brian Schwingle, who leads the forest health program, explains how these reports are crucial for landowners and forest managers. They highlight trends and reveal various threats to trees, helping managers make informed decisions.
In 2025, two significant events shaped tree health in Minnesota. A derecho, a powerful windstorm, struck Bemidji, damaging around 11,600 acres in July. According to the National Weather Service, derechos can be extremely destructive, with winds exceeding 100 mph. Additionally, wildfires in northeast Minnesota were exacerbated by prior spruce budworm damage.
Interestingly, a new insect, the sawfly, was found affecting a small aspen area in Marshall County. Schwingle noted this was unexpected, as this insect hadn’t been recorded in previous reports dating back to 1969. While not a cause for alarm, it is unusual and will require further monitoring.
Schwingle emphasizes the excitement of discovering unusual occurrences in the forest. His team investigates issues that affect forest health, from aerial and ground surveys to in-the-field observations.
Aerial surveys have been a staple since the 1950s, providing valuable data on forest canopy health across Minnesota’s 17.7 million acres of forest. In 2025, they found a decrease in spruce budworm damage, but still reported 182,000 acres impacted. The emerald ash borer, a destructive pest, was identified in six more counties, bringing the total to 59 out of 87 counties in Minnesota.
Positively, there were no new cases of oak wilt reported, keeping the count at 33 counties. Overall, the adequate rainfall during the growing season supported tree health, helping species like oak, aspen, and birch thrive.
Urban trees face different challenges. Common issues include the use of herbicides that harm trees or planting them in poor soil after land development activities. These factors can significantly affect tree health even in residential areas.
Schwingle points out that the community cares deeply about trees, leading to many inquiries about their health. This ongoing interest supports efforts to improve the lush forests of Minnesota.
To understand the importance of these findings, consider this: Trees are as susceptible to diseases as humans. Each species faces its own set of issues like pests and illness. Awareness and regular monitoring can help maintain the beauty and health of Minnesota’s forests for future generations.
For more information on forest health in Minnesota, you can explore the full DNR 2025 Forest Health Annual Report.
