Author's note: The following article is by Anne Torrey, a guest contributor. Torrey was a student in both my Natural Connections writing workshop last winter, and my Master Naturalist training this spring. Here she combines both of those experiences to share with you her newfound excitement for the mesic forest! – Emily Stone.
Speechless, my eyes traveled upward from the sparkling pool at the base of Morgan Falls to the lush, green canopy, and back down to the soft, green mosses carpeting patches of the forest floor. A multitude of ferns and plants rustled gently in the breeze as I moved away from the rushing water into the peaceful embrace of the mesic forest. Surrounded by greenery in every direction, sound was muffled, dampened by the thickness and density of foliage. This place felt primeval, evoking visions of an ancient time before humans walked the earth.
Around twenty thousand years ago, glaciers covered the region we call home. The Laurentide Ice Sheet advanced and retreated over the course of many years, during a period called the Wisconsin Glaciation. The glacial masses scraped powerfully along the Earth’s bedrock, gathering all sizes of rocks as they traveled.
When the mile-high ice floe melted back about 11,000 years ago, it deposited some of these sediments in glacial till. With a nice mix of clay, silt, and sand, these loamy mesic, or middle moisture, soils are not too dry and not too wet. They form the foundation for the rich variety of plant life in the northern mesic forest, where hardwood trees such as sugar maples, basswoods, and yellow birch mix with Eastern hemlock and eastern white pine.
The dense canopy of the northern mesic forest helps to retain valuable moisture, but also creates deep summer shade. Spring flowers like white trillium take advantage of abundant sunlight that shines through before emerging leaves block the sun’s rays. As shade closes in, some ephemerals will go completely dormant. For the rest of the summer, plants in the understory must rely on tiny, filtered specks of sunlight to capture life-giving energy.
As I wandered, enshrouded by lush greenery, I noticed a large mound and accompanying trunk lying on the forest floor. This is called a tip-up and is one of my favorite discoveries when I hike, as they may, on occasion, contain wondrous treasures. When a tree goes over, the root ball is exposed, revealing rocks, fossils, arrowheads, or even bones that lie beneath and tangled within the subterranean system of roots.
The conglomeration of the exposed roots and soil provide a nutritious foundation above the leaf litter for seeds to sprout and thrive as sunshine now streams through the newly opened canopy. This type of disturbance—a single tree falling—is the primary way a mesic forest regenerates itself. New trees may sprout on the exposed soil or take advantage of the increased light. Proliferating in this mass of roots were tiny plants with berries, moss, and a couple of beautiful maroon and green striped flowers called Jack-in-the-pulpits.
The root ball of this tree was not its only interesting element. The trunk had long since begun to decay, becoming a sponge. As it deteriorates back into the forest floor, it provides a nutrient-rich base for more new growth to take hold, such as fungi, mosses, and baby trees. This is important for multiple reasons: mosses help to soak up rainfall, maintaining moisture in the soil and keeping conditions humid. Fungi are essential to our ecosystem as decomposers, breaking down both dead plants and animals, which aids in creating healthy soil. Tree seedlings become the next generation. The mere fact this tree keeled over and exposed its roots enabled an entire miniature ecosystem to take hold.
Making my way back to the trailhead, I thought about all I had seen that day and felt an epiphany of sorts. This beautiful place was the evolving result of a series of occurrences that had taken place over millions of years and continues to evolve even on this very day. Regeneration of the mesic forest is dependent upon the demise of the old, which in turn provides the life sustaining basis for new growth. These are the natural connections that provide the foundation for the circle of life in the magical mesic forest.
For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Growing Up WILD exhibit. Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.