Most alien plants were once ornamental plants that escaped horticultural propagation. The woody aliens exhibit rapid early growth and compete with native species for water, nutrients, sunlight and space.
Aliens are prolific reproducers with high viability and durability, meaning they are genetically enabled to supplant the native plant community.
Some alien plants rely on animals for seed dispersal, and others rely on wind and water.
The worst of these offenders can reduce plant diversity to a monoculture, affecting the balance of the ecosystem. Wildlife feeding, mating, nesting and brooding habits are disrupted as the plant diversity diminishes. Ultimately, the local animal population crashes as their habitat disappears.
The Mississippi sandhill crane, gopher tortoise and other species such as the wild turkey or squirrels have been affected by conversion of their critical habitat to a monoculture of alien plants.
The most versatile, precise and selective methods of ridding an area of alien plants involve a common herbicide and a few hand tools.
Frilling, or using a machete or small hatchet to cut down the offending tree, then immediately spraying the stump with herbicide, is one way.
Another is to make a cut into the tree base and apply herbicide in it. That’s called hack and squirt.
The herbicide glyphosate (sold as Roundup, Accord, or under other brand names) is effective if mixed as two parts herbicide to one part water. Use a common trigger-pull spray bottle to carry and apply the mixture. Make sure to label the spray bottle with the name and dose of the mixture to prevent misuse.
Fortunately, landowners can do something about alien trees and shrubs on private woodlots. Even if you don’t own land, your local NWTF chapter can volunteer to help control alien plants at a local wildlife preserve or refuge.
Several examples of alien trees and shrubs found in the United States are:
- tree of heaven
- autumn and Russian olive
- Chinese tallow tree
- Japanese barberry
- multiflora rose