To Douglas Tallamy, landscaping with native plants isn’t a matter of aesthetics or convenience.
It’s a matter of life and death.
Tallamy worries that the accelerating spread of non-native plants is tipping the balance of nature and threatening to destroy our environment. It’s not just about losing some pleasing flowers and pretty birds. “It’s a matter of the future of life on this planet,” he said.
Tallamy is an authority on the importance of native plants and biodiversity. As a professor of entomology and wildlife ecology at the University of Delaware and director of its Center for Managed Ecosystems, Tallamy studies the ways insects interact with plants and how those interactions affect animal diversity. He has also watched those interactions play out on the 10 acres he and his wife own in southeastern Pennsylvania, and what he has seen troubles him.
When the couple bought the parcel in 2000, it was “10 acres of junk,” he said. Alien plants accounted for more than a third of the plants, and curiously, they showed very little insect damage – much less than the native plants on the property, he writes in his book “Bringing Nature Home: How You Can Sustain Wildlife With Native Plants.”
To Tallamy, that was a red flag. The non-native plants weren’t damaged because the insects couldn’t use them for food or reproduction and pretty much ignored them. He knew that with fewer desirable plants to support those insects, their numbers would decline. That, in turn, would have negative consequences for the birds and other wildlife that eat those insects and the plants that depend on them for pollination.
And the effects would continue right on up the food chain.
Where did those problem plants come from? For the most part, from our gardens, Tallamy said.
About 80 percent of the plants in our yards are non-native, he said. That’s because most of us have fallen prey to the lure of exotic plants, which he said we tend to see as more desirable than the native plants that grow wild.
But those alien plants don’t play nice and stay put. They spread to our fields, forests, waterways and other areas, sometimes reproducing with abandon and choking out the native plants that are a vital part of nature’s system of checks and balances. Indeed, Tallamy said 85 percent of the woody invasive plants that are wreaking havoc on our woodlands are escapees from our gardens – in North Carolina, these are plants like Japanese honeysuckle, Queen Anne’s lace and Chinese privet.
The problem isn’t new.
“As soon as Europeans hit the shores, they started bringing plants with them,” Tallamy said.
Some alien plants arrived as seeds mixed in with agricultural imports. Some were brought in to solve problems, such as the kudzu used in the South for erosion control and the African grasses that were planted in the West for cattle to graze on because those grasses could better survive the conditions.
For the most part, though, those plants didn’t start growing out of control until recent decades. That’s when the population of deer exploded as their natural predators were eliminated, Tallamy said.
Deer prefer to eat native plants, he explained. With more deer and fewer native plants, the animals are wiping out young plants and preventing their regeneration. That leaves a void in the ecosystem that allows non-native plants to take over.
The problem can seem overwhelming, but Tallamy insists it can be controlled. On his own 10 acres, he and his wife – mostly his wife – have gotten rid of all the invasive plants in less than the 13 years they’ve lived there.
He recommends landowners start by assessing what’s growing on their property.
A good plant-identification book can help, as can online resources such as the websites of native plant societies. A local extension educator or park naturalist may be able to answer more specific questions.
Or you can hire someone to assess your property for you, such as a garden designer who specializes in native plants. Already an industry is sprouting up around sustainable gardening, and Tallamy predicted more and more people will be hiring out their services to eradicate non-native plants and replace them with natives.
He recommended starting your eradication efforts with the biggest plants, and just focusing on eliminating a little bit every day. Consider reducing the size of your lawn and bordering it with native plants.
You’re probably going to have to use strong herbicides on some of the stubborn non-native plants, Tallamy said. For example, eliminating Chinese honeysuckle or burning bush requires cutting the plant off at the base and then painting the stump with “something nasty.”
Individual shrubs in the home landscape are probably best controlled by cutting the plant back to the ground in late summer and treating the cut ends with undiluted glyphosate concentrate (Roundup) or by removing the rootball. More detailed instructions for eliminating exotic plants are available from North Carolina State University at ncsu.edu/goingnative/whygo/invspec.html.