No Place for Non-native Species
We write to express our dismay upon reading the piece by Marlene A. Cordon in your June 2015 issue. The article contains much misinformation about invasive plants and their impact upon native plants and ecosystems. We will address some of these:
1. Re: daffodils as “invasive.” Daffodils are not at all considered invasive. They do naturalize, but do not spread appreciably in natural areas and are not found on any invasive plant lists of which we are aware. Often, along roadsides, one can see areas where daffodil bulbs were planted and then multiplied. They are not deleted from invasive plant lists because they are “pretty,” though some invasive plants are considered by some to be “pretty.”
2. Re: “…usually non-native plants fill an area only after it has been left barren because of an altered soil profile…” One of the richest habitats in our area is along rivers in flood plains. Along the Rivanna River, there is an area considered one of the richest for spring ephemeral wildflowers in Albemarle County. It is infested with Garlic Mustard growing in the very rich soil in the flood plain. Garlic Mustard roots secrete a poison that affects soil fungi, which in turn has a negative impact on most plant species. We both see it in the rich soil of many wooded areas.
3. Invasive plants are “…also supporting our wildlife…” Dr. Doug Tallamy is a recognized expert in native plants that support native insects including caterpillars, which in turn provide essential protein for nearly all baby birds and many adult birds. These caterpillars are adapted to eat plants native to the area in which they live, and rarely are able to eat non- natives (that’s why non-native plants are considered to be “pest-free”—yes, pest free because the caterpillars that feed native birds cannot feed on them.) Non-native shrubs also tend to have a somewhat different architecture than native shrubs, which can mean that birds that nest in shrubs may not be as well protected from predators if they are nesting in non-natives.
4. Example: Japanese knotweed. This plant often grows profusely along stream banks in rich soil and shades and crowds out native vegetation. It can survive some flooding and rapidly colonize stream banks. It is not good at holding soil in place and, by preventing native vegetation from growing, vegetation that can help hold soil in place, it leaves stream banks more subject to erosion.
5. It is good to be concerned about herbicides, but most conservationists consider their judicious use to be part of the armamentarium needed to control the worst invasive plants.
There is no place for invasive non-native species in our landscape. Please do not encourage their use.
President, Virginia Native Plant Society
Invasive Species Educator