Article #61, July 2002
By Bill Cook
The impacts of exotic and invasive species are becoming increasingly important among land managers and landowners. Several professional organizations have rated these issues among their top concerns.
What is an “exotic” species?
While definitions vary, essentially it’s a species, plant or animal, that did not occur in a particular region prior to Euro-American settlement. These are species that people have introduced, either by accident or on purpose, that have not evolved with the local flora and fauna. They could be from Finland, Florida, or anywhere that's "somewhere else".
Exotic, or alien, species seldom survive in non-native ecosystems without human intervention. A small percentage become “naturalized”, meaning they can reproduce and survive on their own, such as Scotch pine. A species must be introduced, become established, and then be able to spread. That is a tall order.
While the percentage of these naturalizations is small, it represents hundreds of species as the total number of introductions to North America exceeds 40,000! Keep in mind that most of these introductions are beneficial, such as orange trees, cattle, honey bees, and wheat.
The “invasive” part of the term means a particularly successful species that has the capability to overtake or change part of our ecosystem. Most exotics are not invasive.
Invasive species such as Asian ladybugs, zebra mussel, sea lamprey, and gypsy moth receive a lot of attention. Over 400 exotic species have impacted trees and forests, and more lie on the horizon.
Natural resource organizations encourage landowners to use native plants. More importantly, avoid using the nastiest invasive exotics. Good land stewardship requires learning more about species, native ecosystems, and becoming a better informed landowner.
Better stewardship might include limiting planting choices or monitoring certain activities. In other instances, an eradication effort might be needed for problem species. Eradication can be time-consuming and difficult. Preventing these “outbreaks” is the best route to take, by avoiding the use of invasive exotics in the first place. For example, moving firewood is a common hitch for many exotic pests, especially from a recently killed tree.
Learning the difference between the “good guys” and the “bad guys” can take some time, and not everyone agrees on who should be on which list. Conservation Districts, MSU Extension, the DNR, and other sources offer assistance. If you have access to the Internet, try the Michigan Invasive Plant Council website at: www.msue.msu.edu/mipc.
Caution with exotic invasive species is more than a “feel-good” attitude. The federal government spends millions of dollars each year to protect against new invasions. Between 1985 and 1998, there were 6,446 interceptions of insects in wood from 93 countries. Many millions more have been spent in control or eradication efforts, such as the gypsy moth and the Asian longhorned beetle campaigns.
Exotic insects and diseases have historically done major damage to forest species such as chestnut, American elm, and white pine. Other exotics threaten our beech, oaks, hemlock, balsam fir, pines, and even our mighty maples.
Purple loosestrife threatens our wetlands. European buckthorns are all but eliminating native tree and shrub regeneration in parts of the U.P. Garlic mustard can aggressively overtake native understory plants.
News about the role of invasive exotic species will continue to appear in the headlines. Landowners are certainly a major player in this drama and control millions of acres. Hopefully, most folks will have a positive tale to tell in the ongoing saga.
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Bill Cook is an MSU Extension forester providing educational programming for the entire Upper Peninsula. His office is located at the MSU Upper Peninsula Tree Improvement Center near Escanaba. The Center is the headquarters for three MSU Forestry properties in the U.P., with a combined area of about 8,000 acres. He can be reached at firstname.lastname@example.org or 906-786-1575.
by Bill Cook, Forester/Biologist, Michigan State University Extension, 6005
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