Native plants aren’t always better

Condon is the author of “The Nature-Friendly Garden” and is a Virginia naturalist.

A war is being waged against aliens. Your children are probably being trained and enlisted to fight the battles. Even your local power company may be getting its employees to volunteer in the effort to root out aliens.
Illegal immigrants? No. Non-native plants are the aliens sought out and destroyed.
Yet without these aliens in our midst, our wildlife will find it harder to find food and our soils will not be rehabilitated for the benefit of native plants.
When early European colonists arrived in North America, they found an ancient landscape of huge trees growing on nutrient-dense, dark soil composed of humus. Much decomposition had occurred throughout the eons to produce the rich soil required by the plants growing beneath the leaf canopy.
When settlers cleared the land, they opened the canopy and planted crops that immediately began to deplete the aged soils of their nutrients. Many of the flower seeds brought, intentionally or unintentionally, by the human immigrants became naturalized citizens of their new environment.
Over time, these new plants spread, moving into the clearings where native plants were no longer able to grow because conditions had been altered.
And throughout the next 400 years, people continued to change the landscape as well as bring in new plants that could take advantage of disturbed areas created by man — and sometimes by nature.
Now such plants are considered invasive and are much maligned. But do they truly invade and destroy habitat for wildlife? This perception is unequivocally wrong.
Physics tells us that no two objects can simultaneously occupy the same space. Alien plants verify this by moving only into areas where open space is available for them to grow. After a few decades have passed without native-plant competition, they may fill the area.
So-called invasive, non-native plants are survivors and rehabilitators that can withstand poor-quality habitat (such as highway medians), polluted areas (dredge spoil, sewage sludges and mining tailings, for example) and the well-trodden soil of hiking trails (in national parks and forests).
Indeed, alien species grow successfully in our yards because subsoil has been exposed or topsoil compacted. They also do well in wetlands with soil profiles that have been disturbed by man or weather.
It’s simply not true that many non-native plants are invaders that take over important habitat for wildlife. These plants move into degraded areas that are devoid of good-quality soil upon which most of our native-plant species depend, and we should leave them to do their work.
To try to replace aliens too soon with native plants is misguided; it serves only to impede the necessary rehabilitative process. Once rehabilitation is accomplished, our native plants will move back into these areas.
Man, however, may wish to hasten the process along by removing the non-native species instead of letting them die out naturally. But this task should be done only after the really hard work of transforming the soil so that it is usable by native plants has been completed, free of human effort and expense.
Tax dollars should not be wasted on highway medians in an effort to replace, for example, common mullein with fescue grass that is just as non-native, or purple loosestrife with common cattail that can just as quickly create a monoculture.
Additionally, it’s questionable whether public funds should be spent on the removal of non-native plant species from wetlands with environmental issues, such as degraded water quality.
All of this is not to say that people should deliberately plant non-native species. It is extremely important to maintain our native diversity of insects, many of which are dependent upon a very limited selection of plants to survive. Thus, folks should incorporate native plants into their landscapes as much as possible.
But it’s foolish to root out alien plants that can and do provide habitat for numerous mammal, bird, insect, arachnid, amphibian and reptile species. That’s something bare ground cannot do.