By Kirsten L. Werner, Natural Lands Trust
On a snowy morning in early spring, 1890, Eugene Schieffelin arrived in New York City’s Central Park bearing 60 European Starlings he’d imported from England at great personal cost. His breath curled around him as he bent to unfasten the latch on their cage and release the birds to the grey March sky, their iridescent feathers winking in the half light.
A wealthy aristocrat, Schieffelin belonged to the American Acclimation Society, which dreamed of introducing every bird mentioned in Shakespeare’s works to North America. Many, such as the Nightingale and Skylark, did not survive but the Starlings thrived. By 1928 they were found as far west as the Mississippi. By 1942 they’d made it to California. By the mid-1950s there were more than 50 million of them.
In the 1800s, nature’s complex and delicate balance was not well understood. Today, with our knowledge of the often devastating impact of non-native species on local ecosystems, Schieffelin’s 19th century actions seem naïve and even foolish. But the Starlings are out of the bag, as it were. With numbers now topping 200 million, they are considered one of the most invasive species on the continent. And as they have multiplied, so has their toll on agriculture, public health, and native bird species.
Invasive Plants--Other Good Intentions Gone Awry
Starlings aren’t the only species that were introduced with good intentions but disastrous results. Many of today’s most pernicious weeds were once believed to be beneficial additions to the environment. In the 1930s, the U.S. Soil Conservation Service touted multiflora rose for its use in erosion control and as “living fences” to confine livestock, and state conservation departments encouraged its use by distributing root cuttings free of charge to landowners. European settlers brought garlic mustard to the continent to use as a flavorful cooking herb that doubled as a remedy for gangrene and ulcers. Also known for its medicinal benefits, purple loosestrife was popular in late 19th century gardens.
Whatever useful purpose the plants may have served, the consequences of their introduction have been severe. All considered to be “invasives,” they seed prolifically, grow fast, spread rapidly and aggressively, or lack the diseases and predators that keep their populations in balance in their places of origin. As a result, these plants can out-compete other species and destroy diversity, causing a ripple effect throughout the ecosystem. In fact, invasive plants pose a threat to two-thirds of all endangered plant and animal species.
Managing Invasives --Techniques
As owners and stewards of more than 21,000 acres of land, Natural Lands Trust spends countless hours working to control invasive plant species on our preserves. Woody species—such as autumn olive, Norway maple, and bush honeysuckle—are good candidates for mechanical removal with pruners, handsaws, chainsaws, and brush cutters. However, most of these plants will re-sprout—sometimes vigorously—without some additional attention, so mechanical methods are often paired with chemical ones.
A less obvious approach—but one widely used at Natural Lands Trust—is called cultural control: essentially stacking the deck in favor of desirable species. For example, by replanting an old farm field with a diversity of native trees we “jump-start” the process of succession from field to forest and give the native trees a chance to shade out invasives. Minimizing unnecessary soil disturbance is another important cultural control because it limits the germination of invasive seeds. Biocontrol, in the form of a pair of weed-eating goats named Duffy and Seamus, is another technique the organization uses. The goats are very good on uneven or wet terrain and other places not accessible to tractors
But even with concerted, sustained efforts to manage invasive plants, these species persist. “Natural Lands Trust takes a balanced approach to managing invasive plants,” says Dan Barringer, invasives coordinator for Natural Lands Trust and manager of Crow’s Nest Preserve in Warwick Township, Chester County. “We know they will always be with us, but we do what we can to minimize their impact.”
As daunting a task as it may seem, small victories help keep Dan and the other preserve managers motivated. One such triumph came in the form of an ephemeral wildflower. For the last several years, staff has been diligently pulling garlic mustard from the woodlands at Crow’s Nest Preserve. This noxious weed exudes a chemical into the soil that inhibits the growth of other plants. Recently, Dan discovered a patch of nodding trillium had emerged where the garlic mustard once grew. A sweet success, indeed.
Natural Lands Trust is the region’s largest land conservation organization, preserving open space throughout eastern Pennsylvania and southern New Jersey. Find further details about nature preserves open to the public, upcoming events, ways to support Natural Lands Trust, and more online at www.natlands.org
If you can’t beat ‘em, eat ‘em!
“Invasivores” go a step farther to protect the environment by eating invasive plants and animals. In the spring, try this tasty recipe to make good use of noxious garlic mustard, which threatens native wildflowers and butterflies. For the best flavor, pick the leaves before the plant has flowered (March-April). Be careful to ensure the garlic mustard you use is not chemically treated, and avoid plants growing along the road.
Garlic Mustard Pesto
3/4 cup extra virgin olive oil
1 garlic clove
2 Tbsp pine nuts
1/4 tsp salt
1/3 cup freshly grated Parmesan cheese, about 1 ounce
4 cups of garlic mustard leaves (Alliaria petiolata),
or 2 cups garlic mustard with 2 cups basil leaves
Place all of the ingredients except the basil in a
blender or food processor. Blend until smooth, then
add the garlic mustard and/or basil a handful at a
time, blending until all of the greens are
incorporated and the pesto is smooth.
Makes about 1 cup.