Auto Tour Stop 6
STOP 6: ALIEN INVADERS
The arrival of settlers to the United States also brought several foreign species of plants and animals to America. Many species were brought deliberately to “improve” the compliment of original species. Species such as ring-necked pheasants, carp, brown trout, and the French iris (Fleur de lis) were stocked to provide food, sport, or remind immigrants of home. Other species were accidentally introduced to America by hitching a ride here in our transports. These include common rats, Dutch elm disease, and spiny water fleas.
As travel throughout the world has become easier and more frequent, the number of alien invaders has skyrocketed. Some of these species have become serious competitors with native species. Others have caused damage to our crops, trees, health, or property.
While the Namekagon Barrens Wildlife Area (NBWA) is a relatively remote property, it has not totally escaped these alien invasions. In front of you is an aggressive plant called spotted knapweed (purple flower). It has invaded much of the sandy soiled country and in many cases has out-competed native plants. So far, spotted knapweeds within NBWA are contained mostly along access roads where the land must be mowed and rotovated in order to conduct safe controlled burns. Experience has shown that if left alone, these exotic plants will take over even our most intact plant communities. For this reason, in 2010 DNR Wildlife Management began controlling spotted knapweed with an herbicide that only minimally affects the native vegetation. Also in 2010, leafy spurge (yellow flowered plant), another very aggressive exotic plant, was found on the property just north of this location. Immediate action was taken to control this plant and reduce the impact it would have on the plant community.
Most invasive plants are first established on ground that has been disturbed to the point that native plants are eliminated. Bare ground becomes a perfect bed for foreign seeds to grow. This is why managers regulate such activities as motorized uses, horse riding, and other uses that may create bare trails within wildlife areas.