Tiny’s Great Lakes dunes:
A rare and fragile ecosystem
By Judith Jones, Biologist-Winter Spider Eco-Consulting

Dunes are a changing, moving, dynamic ecosystem. They are a recognizable whole, like a maple forest or a black oak prairie. Our dunes have certain identifiable features, such as dominant plants, the form and shape of the hills of sand, the places where it is wet in the spring, etc. This article will tell you about some of these features and how they work.

On Lake Huron, dune areas usually have a wide, flat area of wet sand next to the water's edge. In recent years, since the water level in Lake Huron has dropped so dramatically, this zone is much bigger than it has been in the past. Since the wave-wash zone is now farther down, in many places there are new plants growing in this zone, especially rushes and sedges. Some people want to scrape this off to keep the sand open, but it can be interesting to watch this area because some real beauties can show up here, such as fringed gentian, the ladies tresses orchid, and blue iris. On the other hand, a couple of good hard winter storms is all it takes for Mother Nature herself to totally wipe out this area. It's a dangerous place for a plant to live.

Where the loose, dry sand begins is a zone of just grass, in particular a big stiff, species called beach grass, or Ammophila breviligulata. Although you wouldn't guess it just by looking, this is a rare species because the dunes where it grows are not common. This grass is adapted to being buried by sand. Its long roots wind around and around, and when the plant is buried it simply grows back up to the surface again. These long roots are the fibers which hold the dunes together and stabilize the sand into mounds. This allows other plants to live on the dunes because it creates a somewhat more stable environment. Beach grass typically grows at the front of the beach all by itself.

sand cherry

Behind this zone, there is usually a higher, flat area where you will find a greater diversity of plants. This zone may be dominated by sand cherry, or by little bluestem (a grass with reddish flower stalks), or by the creeping, evergreen shrub bearberry, or even by common juniper. Sand cherry is a real cherry, with fragrant flowers and black fruits that dry the mouth slightly, somewhat like chokecherries. The fruits can be cooked into a tasty jam. Little bluestem is a handsome grass, native to North America and once a main component of the prairies. Bearberry has small red fruits that could be eaten, but probably wouldn't be your first choice (nor would they be a bear's).


Bearberry

This zone is where you'll find other less common treasures. A bright orange flower the colour of cheddar cheese is Hoary Puccoon, which is a rare species in Ontario. You might also see a greyish-green grass with fuzzy, wheat-like spikelets at the top. This is Great Lakes wheat-grass, and it, too, is a provincially rare species. These plants, and the beach grass, are things that we should avoid stepping on or trampling.


Hoary Puccoon

Interestingly, there are several greyish-green fuzzy plants on the dunes. Others include wormwood, a species of Artemesia similar to the common garden plant dusty miller. Wormwood is biennial. The first year it produces a rosette, and the second year it grows up into a tall spike of teeny, inconspicuous flowers. Another greyish-green plant is the heart-leaved willow, a short shrub with woolly leaves. Perhaps the colour is some kind of adaptation to the high levels of light or heat?

Finally, behind the area of grass or creeping shrubs, there will be more shrubs, larger and closer together, as the dunes begin a transition to forest. Here there will be a mix of forest plants and dune plants, common juniper, Solomon seal, asters and goldenrods, and small trees. Dune forests often have a lot of pines and evergreens present.

Some dunes have weeds present. It's true that one person's weed is another's wildflower, but there are certain characteristics that make weeds what they are. The most fundamental definition of a weed is a plant that isn't wanted in a particular place. However, weeds generally are plants that are not native to the area and don't have their own proper place in the ecosystem, so they end up wherever they can take hold. Often they have the capability to spread quickly and reproduce heavily.

Some examples of common weeds on the dunes include white sweet clover—similar to alfalfa in appearance but with white flowers; bouncing bet—a plant with thick, opposite leaves and 5 notched petals; and star thistle, a stiff, wiry, greyish green plant with small, mauve, thistle-like flowers (but no prickles). All of these plants have the ability to spread throughout the area of the dunes and beyond. Scotch pine, as well, is a species introduced from Europe that now spreads in our area. It has orangy bark and three needles together in a cluster.

The dune ecosystem is not just a collection of plants. It also includes insects, birds, and other animal species. A few noteworthy ones are the tiger beetles which crawl over the sand hunting for smaller insects to prey on. As well, you may come across a small hole in the middle of a cereal bowl-sized depression in loose sand. This is the lair of an antlion larva, which feeds on whatever falls into its pit. Stick a small stick in the hole and see what happens.

Active processes are also a part of the dune ecosystem. To make dunes what they are, you have to throw into the recipe a lot of wind, intense sunlight, proximity to a large body of water, shifting sand, ice build up, and wave scour, to name just a few. Dunes are a much more dynamic ecosystem than say a maple forest. It makes it all the more interesting to marvel at how the organisms which live on dunes area able to survive. It is indeed a harsh environment.

Beyond Mother Nature's hardships, dunes are threatened by our own love for beaches. Because we human beings love the shore and the water, our heavy use of the beach affects the ecosystem. Foot traffic alone can trample plants and even rupture the fabric of roots which anchors down the sand. ATV traffic has an even more pronounced effect. To keep the dunes the way we like them, we need to designate a few official paths and stick to them. Spread the picnic blanket in an area where there is no grass, if possible. Try to keep the kids from running up and down the hills—organize a race out where there is open sand instead. That way, future generations will be able to see these special areas of the Great Lakes the same way they appear to us—open, wild, windy and beautiful.