Drive an hour in any direction in Northern Michigan and you’ll see the landscape change in dramatic ways. The explanation often lies in the soil.
Don’t call it “dirt” — dirt is the stuff that scuffs up your sneakers or collects under your fingernails during a day of yard work. Soil is a complex mix of silt, sand, clay, minerals, microbes and organic matter and holds much of the power in deciding what kinds of plants grow on a landscape.
The massive sheet of ice which carved and shaped Michigan thousands of years ago is long gone but its impacts continue to play a role in the plant life of our region. Along the northern Lake Huron coast, the glacier scraped away material right down to bedrock. Further inland, the mile-thick ice deposited huge amounts of earth in rolling hills as it receded. This is the foundation of Northern Michigan’s diverse forest cover since different tree and plant species have different soil needs.
Soil quality is also determined by the amount of duff — leaves, sticks, grasses and other dead stuff — that accumulates and decomposes over many years, providing essential compost for future generations of plants. Wind and water play a role too by depositing or eroding away soil over time or with sudden events like floods.
There are six basic soil types defined by their mineral makeup and texture— silt, sand, clay, peat, chalk and loam — and soils are usually a blend of these characteristics.
Brittany VanderWall is District Forester at Presque Isle Conservation District where she facilitates the state’s Forestry Assistance Program, a service for private landowners seeking to manage their property for timber production or wildlife habitat. Part of her effort often involves using a soil map, which shows the location of different soil types on a particular property, to help determine where certain tree species will grow best.
“You can almost always overlay that soil map over a forest cover map and there’s a clear trend,” she said.
Presque Isle County admittedly has tough growing conditions for hardwood trees like sugar maples, VanderWall said, due in part to its thin, alkaline soil over limestone bedrock. Sugar maples prefer nutrient-rich soils with good moisture and drainage like those found in higher elevations inland. One exception, she said, is a ridge in Moltke Township that’s 100 feet above the surrounding land and holds the highest quality hardwoods in the county — tall maples prized for their timber.
“That’s thanks to the soils there,” she said.
What it might otherwise lack in hardwoods, the coastal areas of Presque Isle County make up with some incredibly rare and interesting plants that are found exclusively in its bedrock-dominant landscape. Our state wildflower, the dwarf lake iris, thrives here and essentially nowhere else on Earth. So does the carnivorous pitcher plant, which gets its nutrients not from the soil but from catching and consuming flies and other insects.
Back in October, students from Posen High School joined partners of Northeast Michigan Great Lakes Stewardship Initiative including Huron Pines, VanderWall and network coordinator Meag Schwartz for a field exploration trip to Thompson’s Harbor State Park. There they toured a coastal marsh teeming with pitcher plants and used hand trowels to investigate the soil of a nearby forest of birch trees and juniper shrubs.
“My students were able to take away valuable information and skills from analyzing soil samples,” said Posen teacher Stephanie Dege. “They were then able to tie the soil type to the vegetation it supports. This activity allowed them to add to their list of field skills which they will build upon with future trips to the park.”
“Experiences like these are the core of place-based education,” said Emily Vogelgesang, Huron Pines Environmental Education Coordinator. “When students gain a deeper understanding of natural resources in places they are familiar with and have connections to, it sets the groundwork for lifelong stewardship.”
“That’s the bread and butter of what we do — making sure the public is educated and engaged about their land,” VanderWall added, noting her excitement about sharing the magic of soil with the students. “It takes 200 years for an inch of soil to form naturally. When you dig into the soil with a shovel and pull it back, you’re seeing hundreds of years of deposition, and that’s where I sort of geek out.”
Just like our state wildflower, Michigan also has a state soil. “Kalkaska sand” was left behind by the glaciers and covers a million acres of Northern Lower Michigan and the Upper Peninsula. The reddish-brown soil grows grand forests and its excellent water filtration contributes to the health of rivers like the Au Sable and Manistee.
Grab a shovel and geek out about the soils on your land. Just don’t call it dirt.