Cavity Lake Fire 2006 Photo courtesy Carol DeSain.
Feature Story: The Aftermath of Fire: Regeneration after the Cavity Lake and Ham Lake Fires by Alissa Johnson, Contributor
In less than one year two major fire events burned more than 165 contiguous square miles across northern Minnesota and southern Ontario, including portions of the Boundary Waters Canoe Area Wilderness, known locally as the Boundary Waters, and the Gunflint Trail corridor. With only a couple of months of growing season between the Cavity Lake and Ham Lake fires, their ecological impact is arguably the equivalent of one big fire. The same could be said for the emotional impact. The battle to contain the fires, the destruction of the forest, the displaced residents and business owners, and most recently, efforts to regenerate the forest by planting red and white pine have all been well covered by the media. It’s enough to leave canoeists wondering, what’s left? What remains for this stretch of canoe country?
The answer: plenty. Just like Gunflint Trail residents and business owners rebuilt and repaired their properties after the fire moved through, a natural cycle of renewal began to take shape within the wilderness landscape as soon as the fire passed.
Fire Brings a Cycle of Rebirth It may seem surprising to generations of outdoor enthusiasts raised by the sage advice of Smokey the Bear, but natural wildfires have historically been an important part of the Boundary Waters ecosystem. They maintain the existing forest and clear the way for new ones to arise.
The late Dr. Miron Heinselman, a forest ecologist with the U.S. Forest service from 1948 to 1974, spent a lifetime studying and advocating for the Boundary Waters region. His efforts to map the remaining virgin forest within the wilderness area led to the discovery that nearly every stand had originated with a forest fire. Through subsequent mappings of post-fire stands he estimated that fire had occurred somewhere in the region at least once every 80 years since 1600.
The Cavity and Ham Lake Fires collectively burned more than 165 square miles of northern Minnesota and southern Ontario.
In an interview with Canoeing.com last spring, Dr. Lee Frelich, Research Associate and Director of the University of Minnesota Center for Hardwood Ecology, used the jack pine to explain fire’s role. Jack pine has dominated the BWCAW for thousands of years. Its seeds are tucked into tightly closed cones and will only be released by the heat of a fire. Research has shown that a fire must occur every 20 to 150 years to maintain a healthy jack pine forest. If fire occurs too often, the seeds may not be mature. If they are repressed, the seeds may be too old to be viable or the forest may have built up an abundance of fuel that creates a fire so intense it burns the trees and their seeds.
Jack pine forests are not the only stands to benefit from fire. Small fires can maintain red pine and mixed red and white pine forests by burning shade tolerant species encroaching on the stand. Larger fires that burn the forest canopy clear the way for sun-loving, fast-growing species like aspen. In fact, aspen and birch are often some of the first species to move into recently burned areas.
We can see evidence of this latter point on Three Mile Island of Seagull Lake. The island was once predominantly covered by jack pine, yet as Frelich explained, most was felled by the 1999 blowdown. Their seeds were then consumed by a prescribed burn in 2002, and the island is now being colonized by birch. It is in just this way that fire has continued to instigate the evolution of the forest.
Photo courtesy Forestryimages.org
Jack pine cones remain closed until the heat of a fire opens them to release the seeds inside.
The Natural Regeneration of the Forest Brings Much to See
Based on the BWCAW’s fire history, it’s possible to predict what canoeists can expect to see in the Ham Lake and Cavity Lake regions in coming years. It will be far from a bland or desolate landscape.
After fire a forest floor is suddenly flooded with sunlight. Sun-loving plants spring up in numbers and sizes previously unimaginable. In the Ham Lake area, Frelich expects to see widespread Bicknell’s Geranium, a fire dependent plant whose seeds lie dormant in the soil for hundreds of years and proliferate only when fire exposes them to sunlight. He also expects to find large leaf aster growing abundantly in valleys: typically recognizable to canoeists as low growing “lumberjack leaves,” they will be 3 to 4 feet tall with 50 to 100 flowers on every plant. In addition, fireweed and even some invasive weeds like Canada Thistle will thrive.
These plants will be accompanied by tree seedlings. A significant number of trees survived in valleys and pockets of the Ham Lake burn area bedrock. They will act as seed sources and help spread the birch and aspen that thrive in sun. Pin cherry, which buries its seeds much like Bicknell’s Geranium, will also grow, and according to Frelich maple seedlings are also a possibility.
Germinated tree seedlings grow about one foot per year. At such prolific rates, paddlers can expect to find a young forest within five years and in ten years a forest they can walk under. As the trees grow and create shade, Bicknell’s Geranium will phase out and the large leaf aster will once again be recognizable as lumberjack leaves. Shade tolerant plants and trees will begin to thrive, and over time, the young even-aged forest will become more diverse in both type and age of trees.
In the Cavity Lake region, where the fire moved more slowly and burned right down to the bedrock, this regeneration will be slower, perhaps taking a couple of decades. In contrast to the green up of the Ham Lake area, paddlers can expect to see a more barren landscape of exposed pink granite. But there are pockets of mineral soil, and the trees and moss-covered landscape will return.
In truth, it’s an exciting time to visit the region. Paddlers have a unique opportunity to observe first hand the life cycle of the Boundary Waters’ fire dependent forest, perhaps even spotting wildlife that would have previously been hard to see. The black backed woodpecker once rare in the area will be abundant for the next five to ten years – Frelich has seen as many as a dozen a day. And in the next few years moose will flock to the young birch stands. As life returns to the forest, what was calamitous and tragic at the outset has been transformed into a period of growth and renewal, one surely worth observing. For in understanding the natural life cycle of the BWCAW, canoeing enthusiasts gain a deeper connection to the land and become better poised to understand the challenges and issues it faces.
To learn more about Lee Frelich’s thoughts on global warming and its significance for the Boundary Waters Canoe Area Wilderness, see the Wilderness News article Transformation of a Landscape.
