Without fire, red pines could disappear

According to a new computer model, the towering groves of red pine trees characteristic of Minnesota’s Boundary Water Canoe Area (BWCA) could completely disappear unless fire is reintroduced.

Before people settled the area in the early 1900s, fires — started primarily by lightning bolts – swept through the area every 50 to 100 years. While the blazes reduced most vegetation to ashes, they enabled the surviving trees, such as the red pine, to reproduce more easily. But when settlers started taking active measures to suppress natural fires, red pines experienced more difficulty regenerating.

Robert Scheller, a graduate student working with David Mladenoff, a professor of forest ecology and managment, developed a model that shows the outcomes of both fire supression and fires about every 50, 100 or 300 years. He used the landscape simulation model LANDIS — developed at UW–Madison — to predict what might happen if fire was reintroduced.

The model shows that continued fire suppression would lead to the disappearance of not just red pines but also jack pine, aspen and birch trees within 300 years. “If full fire suppression continues,” Scheller explains, “the forest may never recover and red pine may be lost as a locally dominant species.”

The model suggests that fires every 50 to 100 years, as they once occurred naturally, would maintain tree diversity; and, a fire every 50 years would increase the number of red pines.