Silent Invaders
Imagine you see that a campfire has ignited some of the dry leaf litter nearby and no one but you is around. Most of us would know enough to either try to put the fire out, or quickly alert officials to get to the scene. With such early detection and quick action, it is quite possible to avoid an out of control fire that burns thousands of acres.
This “early detection rapid response” is exactly what some scientists hope will soon be commonplace when it comes to a different form of habitat destruction– invasion of native ecosystems by non-native plants. Invasion of natural ecosystems by non-native species may not be as quick as fire, but the damage caused by fast-growing species can result in all the same kinds of dramatic long term changes—changes in soil chemistry, crowding out of native plants, altering natural physical characteristics such as fire and flooding regimes and introducing pathogens.

Invasive species Japanese knotweed alongside highway.
It might surprise you that invasive plants are such a big worry. But they are a serious problem for land managers, agriculturalists and local governments, costing an estimated $120 billion annually across the country for all types of invasives. Almost half of all the threatened or endangered species in the US are in jeopardy precisely due to competition or predation by invasive species.
In Washington, the Pacific Northwest-Invasive Plant Council is taking a lead in tackling this problem. Lizbeth Seebacher, a PhD specializing in invasive species biology, works with the WA Department of Ecology and also serves on the Board of the Pacific Northwest-Invasive Plant Council (PNW-IPC).
“A grant from the National Fish and Wildlife Foundation in 2011 and subsequent grants from the National Forest Foundation and the WA Departmentt of Agriculture, helped jumpstart a program we call EDRR, or Early Detection Rapid Response,” says Seebacher. “These grants have allowed us to establish a citizen science program to identify, monitor and report invasive plants on an integrated GPS mapping program, a program called EDDMapS.”
Seebacher’s colleague, Julie Combs, directs the program which consists of several hundred citizen scientist volunteers who adopt an area or trail and regularly hike there to identify problems and report them.
The PNW-IPC coordinates with the U.S. Fish and Wildlife Service, the Park Service, King County, the Department of Agriculture, the Noxious Weed Board and many other agencies. The goal is to identify problem species and provide a coordinated system for identifying areas of infestation and where spread may be rapid. When citizen scientists find a new outbreak of invasives, it is quickly reported and evaluated.
“Rapid response to a new infestation can be critical, notes Seebacher, “because eradication efforts are most successful in areas under a few acres.” After that, she says, costs can skyrocket.
UW Botanic Gardens creates home for Invasive Plant Council
For many years, the idea of tasking a specific group to take on the challenge of taming invasive plants floundered in a sea of bureaucracy and lack of funding. Fortunately, in 2006 the UW Botanic Gardens sponsored a conference on invasive plants, with now Director Dr. Sarah Reichard leading the charge.
“Because of my involvement on invasive plant species on a national level, I have been invited to speak at the annual meetings of a number of similar non-profit organizations in Florida, California, North Caroline, and other areas” recall Reichard. There was an attempt to start a council here in the mid-1990s, but despite best efforts, it went dormant in 1997. She knew how valuable they could be in partnering with federal, state, and local governments.
In 2006, Reichard was able to secure a US Forest Service grant to bring together an array of scientists from throughout the Northwest doing important work on invasive species eradication, in a conference held at the Center for Urban Horticulture in which Seebacher was hired to work. “There was great synergy at the conference,” she notes, “and the federal funding allowed us to establish a local committee affiliated with the national Association of Invasive Plant Councils.” The second afternoon was dedicated to a lively discussion of what the PNW-IPC could be.
Reichard was also responsible for getting approvals to house the local plant council at the UW Botanic Garden, where she is now Director.
“Thanks to energetic scientists like Julie (Combs) and Lizbeth (Seebacher),” says Reichard, “we have a vibrant local invasive species council, excellent collaboration with agencies and hundreds of citizen volunteers who are working to keep invasives out of our natural lands.”
Lovely Villain

Forest overgrown with English Ivy
Once prized for its graceful presence decorating brick edifices, English Ivy (Hedera helix) has become one of the most familiar invasive plants in our region. It is actually a European native species on the list of noxious weeds in several states, including Washington State. The qualities that initially made English Ivy a popular ornamental are the same ones that make it invasive in the right environment—it grows rapidly, needs little light or water once established and is extremely hardy—it forms dense mats on the ground and can climb up trees and shrubs. English ivy can choke off life in native shrubs by preventing light from reaching the shrub due to the density of ivy. The sheer weight of the ivy can weaken the plant it has grown on and make it more susceptible to blow-down and disease.
The clusters of black berries are eaten and spread by birds which makes dispersal easy and widespread. In Stanley Park in Vancouver B.C., for example, 700 volunteers removed more than 20,000 square meters of ivy in a recent work weekend. Despite this comprehensive effort, scientists estimate that it will take 50 years to rid Stanley Park of this invasive pest!
An Alliance with Commercial Nurseries
There are many sources responsible for introducing invasive species into natural ecosystems, says Seebacher. Invasives can arrive as seed in agricultural products, or on shipments from overseas. In the past, officials in the highway departments selected median strip plants for their resilience and adaptable nature, not recognizing at the time the threat it might pose to native ecosystems.
“We are trying to limit the sources of infestation,” says Seebacher, “and an important ally in this effort are local nurseries.”
“So our next big task is to create a Nursery Certification Program,” she says. The PNW-IPC will be developing a list of species they will ask nurseries not to sell because of the high potential for that plant to become an invasive ‘villain’. The scientists can also provide ideas for alternate species for nurseries to sell with many of the same decorative characteristics but fewer of the negative consequences for the environment.
“Most home gardeners would not want to be a part of propagating aggressive invasives into the environment,” Seebacher notes. “This program will help everyone play a part in keeping these costly pests from spreading in our natural landscapes.”