Slugs

Have you ever really looked at a slug? Not many people have, I would guess, except for gardeners who pluck them off ripe tomatoes. I first began to appreciate them after watching a French documentary called Microcosmos. It is a stunning film that captures a day in the life of a meadow – from a bug’s eye view. The crowning scene, for me, is a romantic encounter between two snails. Their antennae touch tentatively, then caress enthusiastically. It is all undulating, glistening slime on a bed of vibrant moss as they slowly topple over in ecstasy. Whew! A bit steamy, even for invertebrates. Snails, of course, are relatives of slugs. Slugs are basically snails that have adapted to living in areas without much calcium from which to make a shell.

Just the other morning I found some slugs on my driveway doing very important work. There were about ten of them, each bright gold body just over an inch long. They were gliding hungrily over a giant pile of bear scat. Slugs are decomposers – unsung heroes of nature. Unless you are an avid gardener with an active compost pile, you probably do not think about decomposers often. They work in the dark, dank depths of the world, neatly breaking down organic material into the ingredients for new life. Each beautiful wildflower, every fresh tomato, is made possible by behind-the-scenes decomposers.

At science camp, we called this team the “F.F.B.I.,” which stands for fire, fungus, bacteria, and invertebrates.

Some plants have very specific partners – like the trailing arbutus I mentioned last week, with its mycorrhizal relationship with fungus on its roots. Jack pine is a classic example of a plant that likes to collaborate with fire, since the resinous cones and tiny seeds of the tree need heat to open, bare soil to germinate, and a ready supply of nutrients from the ash. Ants are an invaluable invertebrate both to peonies, who need ants to chew open their buds, and to trilliums, who need ants to plant their seeds.

Human tinkering can disrupt these partnerships. Earthworms can increase nitrogen in the soil, but while that is good for your tomatoes, it can be bad for native plants. Earthworms are not native in lands like Northern Wisconsin, where glaciers still froze the ground solid just 10,000 years ago. Escapees from gardens and bait buckets invade forests. Maple seedlings and wildflowers actually need the fallen leaves for seed germination, and these European earthworms are too efficient at their vocation of decomposing the leaves.

The connectedness of nature became apparent when researchers discovered that earthworms are to blame for the population decline in ovenbirds, a ground-nesting warbler. Less leaf-litter means fewer insects for the ovenbirds to eat. Taller flowers and ferns that thrive in thick leaf litter are thinning out and being replaced by grasses and sedges that do not provide good nesting cover.

Like all things in nature, balance is necessary for a health. Worms are helpful in some ecosystems, but worms in the wrong place upset the balance. Too much fire will sterilize the soil; too many insects may decimate a tree. Wintergreen in the road ditch has beneficial fungus on its roots, and a powdery white pathogenic fungus on its leaves. Consider our own bodies where there are multitudes of helpful bacteria and a few that can cause serious harm. In trying to manage the harmful ones, we do not want to eliminate everything.

So as you admire the conspicuous beauty this spring, remember to appreciate the web of support that keeps it going. We all need “decomposers” in our lives – those partners who help us to nourish our souls, break down barriers, clean away debris, turn failure into beauty, and cycle with joy through many seasons of growth and renewal.

Think about that the next time you see a slug!

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, STAR POWER: Energy from the Sun, opens in May 2012. Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Also discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/