Economic and Ecological Impact of Invasive Species

Invasive Species in the United States

Outbreak populations of invasive species in the United States cover a land and water area approximately the size of California, at over 100,000,000 acres!

The annual economic cost (including impact and control measures) to the United States is well over $120 billion/year.

Characteristics of Invasive Plant Species

Invasive plant species owe their success to one or more of the following characteristics:

• They tend to be generalists that tolerate a variety of different habitats.
• They grow rapidly and often produce abundant seeds.
• They lack natural enemies (competitors, predators, parasites) in their new ecosystem.

Profiles of Invasive Species

Mile-a-Minute Vine

One found in Fowl Meadow on trip: mile-a-minute vine.

Melaleuca (Melaleuca quinquennervia)

An Australian tree that was first introduced into south Florida in the early 20th century. It displaces sawgrass marshes in the Everglades and adversely affects hydrology by drawing down water.

Cheatgrass (Bromus tectorum)

Accidentally introduced from Europe in the late 19th century, it quickly spread across overgrazed rangelands and has replaced native grasses across much of the western U.S.

Kudzu (Pueraria montana)

Kudzu is a vine native to Asia that was deliberately introduced to prevent erosion in deforested regions of the Deep South. It blankets and smothers native trees and shrubs, as well as buildings and farm machinery!

Gypsy Moth (Lymantria dispar)

From Europe and Asia, the gypsy moth was first introduced to Medford, Massachusetts in 1869 as part of an effort to begin a commercial silk industry. The caterpillars annually defoliate millions of acres of trees; outbreak years are especially damaging.

Zebra Mussel (Dreissena polymorpha)

Native to Russia, it first appeared in 1988 in Lake Erie, believed to be introduced by the ballast of ships traversing the Saint Lawrence Seaway. The mussels outcompete native shellfish, foul boat hulls, and clog industrial water intake pipes.

Artemisia (Artemisia vulgaris)

A large perennial weed native to Eurasia; it has squarish stems, deeply dissected leaves, and numerous small flowers on terminal spikes. It tends to form thick stands that exclude all other species.

Common Reed (Phragmites australis)

A tall reed with dense seed heads; a native subspecies (P. a. americanus) occurs in parts of New England, but the Eurasian subspecies (P. a. australis) is problematic because it forms huge monocultures in marshes and excludes less common native species.

Multiflora Rose (Rosa multiflora)

A densely spreading perennial shrub that is native to Japan. It is a generalist that forms dense, impenetrable thickets and rapidly outcompetes surrounding vegetation. Fringed stipules and several fruits on one inflorescence are distinctive.