New England Reports

A review of Invaders, a special issue (volume 2, No. 3, 1998) of the New England Wild Flower, Conservation Notes of the New England Wild Flower society. For more information call them at (508) 877-7630 or visit their website: http://www.newfs.org/

New England's Green Invasion
This article summarizes the conflicts that complicate the exotic plant issue.

1. native versus nonnative,
2. personal experience vs. the larger picture,
3. ecology vs. economy,
4. act now or wait for all the facts.

The explanations are practically put. William Brumback's bottom line is "our ability to understand the effects to ecosystems is still very limited, we should not take the threat posed by invasive exotics lightly. History is full of ecological disasters caused by human neglect or hubris."

Legacy of Concern
Leslie J. Mehrhoff documents our long history with invasive non-indigenous plant species, beginning as early as 1735. A Philadelphia botanist was alarmed to see lilacs and double narcissus "already too numerous" around his City, "as the roots brought by early settlers had spread enormously." He notes that until the 1980's "little official concern was shown for non-native invasive plants. Although the movement was slow to start, each year more people become concerned about the problem of invasive species. People are increasingly aware of the negative roles these invasive species play in natural plant communities." (Mehrhoff is the Curator of the George Safford Torrey Herbarium at the University of Connecticut. He has been documenting the spread of non-native invasives around New England for 25 years.)

Biology of Plant Invasiveness
Dr. Mehrhoff defines the traits of invasiveness:

1. Produce abundant fruits and seeds. Autumn olive, purple loosestrife and multiflora rose are examples of invasives that produce large amounts.
2. Disperse seed easily. Floating seeds/purple loosestrife, bird carriers/honeysuckles, wind blown/tree of heaven, vegetative propagules/Eurasian milfoil, and human vectors are such mechanisms.
3. Establish easily and quickly. Disturbance is key to such a response from species such as Japanese barberry or garlic mustard.
4. Grow rapidly. This advantage allows vines to climb quickly, such as Oriental bittersweet and mile-a-minute.
5. Compete aggressively. Having left behind their natural competition, fields can be overrun by aggressive species like Queen Anne's Lace, Canada thistle, and others.

Purple loosestrife, Lythrum salicaria spp., a colorful invader.

Roots of Trouble/Seeds of Change
Cheryl Lowe discusses the role of nurseries and botanic gardens in the introduction of invasive species. In 1996, S. Reichard and F. Campbell reported that "of the 235 woody plants known to invade natural areas in the U. S., 85% were introduced primarily for ornamental and landscape purposes. This leads us to an important point, the point before introduction. "The key time for preventing a new introduction from becoming a problem is before wholesale promotion and production begins, before an economic commitment has been made. Preventive evaluation by all who introduce new plants into the trade can have enormous positive impact

Lifestyles of Invasion: Three case studies.
Garlic Mustard (Alliaria petiolata), Buckthorn (Rhamnus cathartica) and Eurasian Watermilfoil (Myriophyllum spicatum) were chosen for an in depth analysis because the three are well established in the Northeast. The methods of dispersal and problems of control are representative of many invasive plants.

Rogues Gallery: New England's Notable Invasives
The plants chosen for this discussion are considered particularly troublesome and likely to increase over time. The Gallery includes: Autumn Olive (Elaeagnus umbellate), black locust (Robinia pseudoacacia), black swallow-wort (Wincetoxicum nigrum), burning bush (Euonymus alatus), cypress spurge (Euphorbia cyparissias), goutweed (Aegopodium podagraria), honeysuckles (Lonicera morrowii, tatarica, maackii, and more), hydrilla (Hydrilla verticillata), Japanese barberry (Berberis thunbergii), Japanese knotweed (Polygonum cuspidatum), Japanese stilt grass (Microstegium vimineum), Mile-a-minute (Polygonum perfoliatum), multiflora rose (Rosa multiflora), Norway maple (Acer platanoides), oriental bittersweet (Celastrus orbiculatus), phragmites or common reed (Phragmites australis), porcelain berry (Ampelopsis brevipedunculata), spotted knapweed (Centaurea maculosa), tree of heaven (Ailanthus altissima), water chestnut (Trapa natans), wineberry (Rubus phoenicolasius), and yellow flag iris (Iris psudacorus).

What are our Options?
"The invasion of noxious alien species wreaks havoc on America's environment and economy that is matched only by damage caused by floods, earthquakes, mudslides, hurricanes, and wildfire. These aliens are quiet opportunists, spreading by a slow motion explosion." Bruce Babbit

Because the spread of invasive plants costs us 4,600 acres of wildlife habitat per day on public land alone, this article explores what is next. The management of one species alone, Purple Loosestrife, is estimated at $45 million per year. Each year invasives go unchecked, the ecologic and economic pricetags rise. Public awareness about biological invasions is not adequate. A number of New England State' Environmental Protection Departments are writing fact sheets, guides, etc., with the help of The Nature Conservancy. The Garden Club of America has taken on an "Alternatives to Invasives" campaign. Many coalitions of citizen groups are likely to emerge over this issue.

For reprints of the original publication, Invaders Magazine, write New England Wild Flower Society, 180 Hemenway Road, Framingham, MA 01701. Inquire about quantity discounts.