During your one-mile hike on the succession trail you will travel through time from a young community on the foredunes to the woodland dune forests that took thousands of years to evolve. At the turn of the century, Professor Henry Cowles from the University of Chicago helped create the science of ecology, when his studies showed a dune of sand where only the hardiest plants survived could change to soil rich enough for a woodland dune forest.
As you hike with the students, have them notice the sharp change of plants on the long narrow foredune just above the beach. Without the sand-holding abilities of the foredune marram grass, the first dune would not rise high enough to provide the shelter from the wind that sand cherry, sand reed grass, little blue stem and other plants need to grow.
Professor Victor Shelford explained that animal communities go through succession too. The diversity of animal life increases as you hike from the beach through the plants on lee side of the dune and up to the hardwood forest. Look for their signs.
The human created blowout near the pine community has already engulfed the boardwalk below and threatens to invade the jack pine community. The precious little soil that took hundreds of years to create will become buried in sand as the pines are covered. The plant community might revert back to plants more tolerant to the shift sands.
This would not be the first forest to disappear under the sands. The ghost trees, exposed in the blowout near the jack pines, are evidence that succession in the dunes can go both ways. Succession is not a straight line from beach, foredune, jack pines, to a woodland dune forest. Notice that environmental changes like fire, shifting sands, or human disturbances cause the most obvious changes in succession of these plant communities.
Succession is evident through the lakeshore. Homes, fields, and industrial sites, bought to create the National Lakeshore in 1966, soon were covered with pioneer plants like the sun-loving grasses, ferns, and wildflowers. In turn they provide a suitable habitat for the seedlings of vines, bushes and sun-loving trees. Within a few years, thickets of blackberry, poison ivy, and sumac trees started to replace the grasses. Later, they provide the proper conditions for the germination of oaks and hardwoods trees that will eventually grow to replace them. The woodland dune forest is the climax community.
Forest fire is one way succession reverts back from a climax forest community to pioneer plants. Many species of plants and animals are dependent upon natural wildland fires to create open areas. The Karner blue butterfly has become endangered by the loss of habitat to human building and the suppression of fire. Prescribed burns in the park are necessary for slowing plant succession.
Project Wild Elementary Activity Guide has two classroom activities about succession, "Forest in a Jar" and "Pond Succession", pages 91 to 94.
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