A profusion of yellow from the hairy puccoons intermixed between the exploding white blossoms of the sand cherries delight the May visitors who have waited too long for spring. The new green shoots of the marram grass indicates these important dune builders are growing again and will continue to hold the sand in place.
Surviving the barrage of sand brought by the wind, the marram grass prevents a sand burial with specialized underground stems called rhizomes. Able to elongate when covered with sand, the internodes of the rhizomes may grow eight feet up through the sand to reach sunlight. With the ability to spread up to 20 feet in all directions their thread-like roots act like a net under the sand thereby stabilizing the dunes.
Fun Stuff - To highlight how the marram grass roots interlock and form a net to hold the sand, have the students play this variation of red rover. Play it on the beach before hiking into the foredunes to prevent walking on the plants and damaging them. Have four students stand in a line holding hands. They represent marram grass and its roots. Allow a student to run up and try to break through between two students. If the student is unsuccessful they make the dune larger by joining the line. To prevent anyone from getting hurt, have the students run uphill. Strong students should be limited to attempting to break through the line where two other strong students are holding hands.
Cottonwood leaves rustling in
the wind provides welcome shade in an exposed environment. Seeming out of place in this
sandy, bright, almost desert-like foredune the cottonwood adaptations are only revealed to
the careful observer. Sprouting in low, sheltered spots, the young tree can survive sand
buildup by the time it’s a few feet tall.
If the tree limbs are covered with sand they will sprout roots. Likewise, if the wind exposes the roots by blowing away the sand, the roots will sport new stems and leaves. What might appear as a small tree may be a 50-foot tall giant covered by the shifting sands.
Quick Activity - Give students the time to search for evidence of animals in this community. The zipper-like tracks of beetles are a road map of their activities. Tail impressions between fast moving feet tracks are left by the six-lined racerunner, a lizard that was searching for its insect meal. Toads hop under the grass and it’s a lucky group that discovers a toad’s tracks ending at the scene of a struggle with a snake. Remember, please do not destroy the dunes by walking on the plants.
Hawks circle overhead looking for white footed
or deer mice. An Eastern Kingbird is conspicuous as he perches on a cottonwood limb.
Bursting into a quick flight that often looks like aerial combat, the Kingbird returns
with an insect to the same tree.
Hiking behind the foredune nearest to the beach, you will notice how the
community changes from the pioneer marram grass and cottonwood trees that are stabilizing
the dunes. In late summer, monarch butterfly caterpillars eat the leaves of the butterfly
weed while adult butterflies visit the orange flowers. Grapes provide late summer food for
sparrows and goldfinches that also come to eat the marram grass seeds. Don’t confuse
the poison ivy with the three lobed leaves of the hop tree. Prickly pear cactus, little
blue stem and sand reed grasses are members of this community.
Quick Activity – Once Lake Michigan is blocked from your view by the first set of small dunes have the students sit on the trail and make the same observations about sunlight, wind, soil temperature, and soil moisture. They should make their observation about the areas with the plants on it, not the bare soil of the trail. Sitting on the trail helps prevent damage to the plants and protects the dunes.
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