When I was child I watched an old black-and-white horror film called “The Day of the Triffids.” It was about deadly alien plants from outer space, called triffids, which come to earth to kill humans; most of who were blinded by the lights of a meteor shower that brought the triffids to our planet and could not see the approaching threat until it was too late. That movie terrified me back then.Imagine my surprise then when I grew up and learned that there were real invading, killer plants spreading across our world; their spread being blindly aided by humans who helped move the plants from place-to-place and habitat-to-habitat, and in many cases were intentionally planting them.
Of course the real invaders are not aliens from a different planet, but from right here on earth, and while these alien invasive plants are not necessarily chasing down and killing humans they are causing the deaths of many plant and animal communities around the globe.
Many common invasive plants started out innocently enough as beautiful ornamental plants used for landscaping, or as potential food and medicinal purposes. In many cases, the U.S. Government was responsible for the spread of many of invasive plants in the U.S.
When “The Day of the Triffids” was released in 1962 it had been almost thirty years since the severe drought and the resulting great dust storms had spread beyond the Dust Bowl region of the country resulting in the collapse of the U.S. agriculture system and economic hardship for much of the country. The U.S. government stepped in with innovative programs to stabilize both agriculture and the economy. One of those programs was the Soil Erosion Service, which transformed into the Soil Conservation Service, and is known today as the U.S. Department of Agriculture’s Natural Resource Conservation Service. The Soil Conservation Service, like its name suggests, was tasked with revising agricultural practices at the time to conserve and prevent the further loss of top soil in Midwestern farm states like Wisconsin. The Service developed a variety of beneficial farming practices to reduce erosion, like terracing and contour cropping. Another practice the Service developed was the creation of wind rows and plantings for wildlife food and cover, which were comprised of fast-growing plants with spreading roots to hold soil in place, and potential food crops, like berries, that might benefit a variety of wildlife. Some of these plants that were promoted included Multiflora Rose (Rosa multiflora), honeysuckles (Lonicera spp.), and privets (Ligustrum spp.).
Today, we are paying the price for the decisions of our past, both economically and ecologically. Researchers with Cornell University estimate that $120 billion are spent annually on economic losses and environmental impacts due to all invasive animals, plants, and microorganisms in the U.S.
There are an estimated 17,000 native plant species in the U.S., and many many more that are considered introduced. Of the introduced plant species in the U.S. approximately 5,000 have escaped and become invasive in natural habitats. $100 million/yr is spent on controlling these invasive plants in the U.S. In agricultural systems invasive weed plants contribute to nearly $24 billion in crop losses every year, another $1 billion annually on forage losses in pastures, and ranchers spend an estimated $5 billion/yr controlling weeds that may be toxic to cattle in pastures and ranges. In residential areas it’s estimated that $500 million are spent annually by homeowners to control invasive weed species in lawns and landscaping, and $1 billion is spent on weed control management on golf courses.
While there has been much research on the impact of invasive plants on native plant communities, we are beginning to gain a better understanding of how invasive plants are impacting animal communities. Birds, which share close relationships with plants, may face the greatest danger posed by invasive plants.
To learn why and how you can start using native plants in your landscaping projects consider attending the Native Gardens Workshop at Aullwood Audubon Center & Farm on March 28th, 2009. You can get more details and register for the workshop by contacting Aullwood directly.
