In the springtime forest a sea of dew-drenched wildflowers glistened in the sun. These plants advanced along the forest floor as far as the eye could see - or, to the edge of my neighbor's lot line.
I straightened my aching back then dove back in, extracting plants one by one and throwing them atop the compost heap behind me. Pull, toss, repeat. Again and again, inching forward against the tide of white flowers.
The plant? Garlic mustard. It is lovely, but it's also an invasive weed - just one of a milelong list of invasive species in Illinois.
May has been designated Illinois Invasive Species Month. The purpose is to educate people about the problems of invasive species and to rally the troops to fight the inexorable advance of invasive organisms.
What they are
What is an invasive species and why are invasives such a big deal? Typically, an invasive species is an organism that originated in one part of the world and traveled to a different part of the world, on its own or with outside help. From herbaceous plants to shrubs, from insects to birds, earthworms, carp, zebra mussels, and ladybugs, invasive species come in many forms and from many places. The new kid on the block is often aggressive and usurps native species on their home turf.
The effects of one invasive species in an ecosystem can set off a chain of negative ecological consequences.
You may know firsthand at least a few invasive species, even if you weren't aware of their ecological status. For example, you may have pulled Queen Anne's Lace from your garden. Or you may have planted honeysuckle for a hedge. You may have lost a shade tree to the emerald ash borer, or evicted a family of starlings from your porch walls.
What they do
What harm do these invasive species inflict? Some of them are actually pretty, like purple loosestrife. But beauty is deceptive. The common problem with invasive species - beautiful or homely - is their ability to out-compete native plants and animals and cause a decline in the diversity, and therefore the health, of the ecological communities. Invasive species also affect soil, compromise water quality, and alter the landscape.
When an invasive species establishes itself in a natural area, it may take over to the point of creating a "biological desert" - i.e., a community in which there is nothing growing but that particular species.
Matt Williamson, restoration ecologist for the Forest Preserve District of Kane County, said that chervil tops the list in Kane County. His concern is based on chervil's phenomenal ability to reproduce and spread to roadsides, fields and natural areas seemingly overnight. It has exploded into bloom along roadsides, bike trails, and ditches. The challenge for Williamson is to keep it out of our natural areas.
In addition to chervil, there are plenty of other ubiquitous herbaceous plants on the invasive species list. Reed canary grass, purple loosestrife, white and yellow sweet clover, multiflora rose, Canada thistle, crown vetch, teasel, and bush honeysuckle to name just a few.
Where they came from
How do these troublemakers get here? Garlic mustard is a good example of a well-meaning introduction gone awry. Native to Europe, this pretty white-flowered plant was long used an edible and medicinal herb in the Old World. Knowing its culinary and pharmaceutical uses, 19th century settlers brought it to the North America for the same purposes. The plant behaved itself nicely as a garden herb from its arrival in the 1860s for over a century. Then, in the 1980s, it escaped the confines of cultivated gardens and swept through forests and woodlands of 29 states like a tidal wave, displacing native grasses and herbaceous plants in its wake.
In the animal kingdom, another intentional introduction that went amok is the house sparrow. These birds came from their native England by invitation. Commissioners of New York City's Central Park thought these cheerful songbirds would make a good addition to the park, so in 1850 they released 50 pairs to join the indigenous birds in the area. One slight problem: the house sparrows not only joined native birds, they pushed them out. In the span of a several decades, this diminutive bird spread from New York to California, north to Hudson Bay in Canada and south into Mexico. By 1910 the house sparrow was well established throughout North America and Central America - it had also been taken to Australia and established itself Down Under. It's now the most widely distributed bird in the world, to the detriment of native avifauna everywhere. A very successful British invasion indeed.
The local impact
The scope of the problem of invasive species is enormous. According to Williamson, "Invasive species impact every single one of our preserves, even the most quality natural areas."
Thus no piece of ground in Kane County is immune - even your garden.
The forest preserve district carries out a comprehensive natural areas management plan to restore and preserve ecological health to some 18,000 acres of preserves.
"Everything we do is impacted by invasive species," Williamson said. "When we seed native plants in prairie and woodlands, we do everything to kick-start competition to prevent invasive species from gaining ground."
How you can help
Individual citizens (yes, you!) can also make a difference. First, before you purchase a plant at the nursery, do some research. Be careful what you plant; many plants sold for gardens are expert escape artists and may proliferate beyond your borders.
Check the New Invaders Watch website -- http://ctap.inhs.uiuc.edu/newinvaders/target_species.aspx -- for species that have the potential to become serious problems.
In addition, the forest preserve district has monthly restoration workdays throughout Kane County all year round where volunteers help clear invasive species and harvest and spread native plant seed to replace what they've removed.
There are also several special events throughout the year where volunteers can help pull garlic mustard, plant trees and collect and spread native seed. For details, call (630) 762-2741.
• Valerie Blaine is a champion garlic-mustard puller and native seed-spreader. She works to restore health in her woods in St. Charles, and she is the nature programs manager for the Forest Preserve District of Kane County. You may reach her at email@example.com.