Property owners should go native

With the threat of frost finally over, many people will head to their favorite garden center or nursery this holiday weekend. As you shop, consider this lesson in plant ecology.
Many gardeners favor showy, exotic plants, but fail to consider the ecological implications of landscaping millions of small backyards. The total amount of backyard habitat in the U.S. is staggering. Though apartment dwellers may maintain only a window box or two, quarter-acre lots are common, and many people maintain backyards that encompass an acre or more.
According to the 1998 Statistical Abstract of the United States, American backyards total at least 35 million of acres. That's more than 50,000 square miles of backyard habitat. Unfortunately, the typical American homeowner has been brainwashed to believe that backyards, regardless of size, must be sprayed, fertilized, mowed and manicured into submission.
Require less attention
In truth, backyards dominated by native plant species are better for butterflies, birds and other backyard beasts, and they require less attention and expense than gardens dominated by exotic plants.
Ecologists estimate conservatively that 50,000 non-native plant species have been intentionally or accidentally introduced into the United States. Of those, about 5,000 have established themselves as part of the wild plant communities, and many have become invasive. Multiflora rose, kudzu, autumn olive, purple loosestrife and Asian bittersweet come immediately to mind.
Invasive species spread rapidly and dominate landscapes because they outcompete natives for sunlight and nutrients. Some degrade aquatic habitats by promoting soil erosion. Some decrease the diversity of microorganisms in the soil. Some compete so aggressively and successfully they harm endangered native species.
Just as house sparrows and European starlings disrupt the nesting ecology of native cavity-nesting birds, invasive exotic plants wreak havoc on native plant communities. And we are responsible for this ecological disruption because we fail to discourage exotic plant species.
One aspect of exotic plant invasions that has only recently begun to get attention from biologists is the ecological impact that occurs when exotics replace natives. Specifically, we know little about the effects of this transition on the food habits of plant-eating insects and higher predators such as birds that eat those insects.
Specialists
The vast majority of plant-eating insects are specialists that eat only a few closely related groups of plants. (Monarch butterfly caterpillars, for example, eat only milkweeds.) These relationships have evolved over long periods of time, so native plant-eating insects can efficiently use their preferred host plant's tissues as an energy source.
Furthermore, when insects become specialized to eat one related group of plants, they lose their ability to efficiently consume unrelated plant species. Exotic species are obviously unknown to our native plant-eating insects so native insects should have trouble digesting exotic plant tissues.
As invasive plant species begin to dominate a landscape, native insects will be unable to use the solar energy stored by these exotic plants. Over time, that is devastating for native plant-eating insects and the predators that eat these insects. That list would include insectivorous fish, frogs, toads, salamanders, lizards, snakes, birds and many small mammals. Invasive plants have the almost inevitable ability to disrupt entire food chains and native ecosystems.
Over time, invasive plants have the potential to not only alter the species composition and diversity of plant communities, they also can alter an entire ecosystem's flow of energy by disrupting the interconnected food chains at every level. If insects that eat native plants disappear when invasive plants take over a landscape, the herps, birds and small mammals that eat those insects will be in jeopardy as well.
The solution is simple. Landscapers and property owners large and small must "go native." In the long run, natural gardens are not only be more ecologically responsible, they are easier to maintain and cheaper to create. And because natives are adapted to local conditions, they grow and prosper vigorously.
Send questions and comments to Dr. Scott Shalaway, R.D. 5, Cameron, W.Va. 26033 or via e-mail to sshalaway@aol.com.