To the Editor:
Larry Wethington’s letter of Nov. 26 raises an important question. What is a native, he asks? Basically it is a plant or animal that was here at the time of settlement in the 17th and 18th centuries when the ecosystem was in balance. Plants had evolved over thousands of years to survive the rigors of droughts, floods and prairie fires, and there was enough food to go around. Predator and prey co-existed. “Balance” is the key word here.
Human intervention took that away. An example of destructive human intervention is in the South where kudzu imported from Japan has run rampant and choked out beneficial plants — that is, plants that provide food for us or for the rest of the natural world. Because kudzu has no natural enemies in America, it can smother the plants on the land where it takes root. Monarch butterflies, for example, won’t find nourishment from kudzu leaves, but they will from native milkweed.
We don’t need to worry about kudzu in the Chicago region, but look at our deer problem. Two hundred years ago, there were wolves that kept the deer population in check. Now we have virtually eradicated wolves (not that we want them prowling through city streets) but the situation is no longer in balance.
Human intervention in functioning ecosystems has thrown many habitats out of whack. Why do we have declining numbers of songbirds? If we don’t grow the plants where they can find food and shelter, they won’t reproduce and they will disappear. Just because a tree or shrub is green doesn’t mean that it can provide food for a cardinal or a robin.
If we want to live in a world that contains robins and cardinals, plus butterflies, fish, pollinating insects and all of our native mammals, we need to provide the plants that will support them. If we want to have food for ourselves, we need to provide plants for pollinating insects such as bees. Again, just because a flower is pretty doesn’t mean that it will feed a bee.
So that’s why they’re cutting down certain trees in Jackson Park. They’re trees that aren’t providing food for the wildlife that we both want and need. For more information, I recommend “Bringing Nature Home” by Douglas Tallamy. It’s full of well-documented examples of how native plants are necessary to our health and that of the planet.
One interesting fact: The widely planted Bradford pear that we see blooming here every spring is not only an alien species; it is actually toxic to wildlife that tries to eat it, says Tallamy. Our various native oak trees, on the other hand, can support a grand total of more than 500 species of butterflies and moths. So if someone cuts down a Bradford pear and plants an oak in its stead, don’t cry. It’s not worth it.
Carolyn Ulrich, Editor