Weed Management and Invasive Species Control - Project Planning and Management for Ecological Restoration - page 188

Box 12-2. Helpful Websites for Invasive Plant Management
European Weed Research Society
http://www.ewrs.org
Introduced, Invasive, and Noxious Plants, Natural Resources Conservation Service,
United States Department of Agriculture
http://plants.usda.gov/java
The National Invasive Species Counsel
http://www.invasivespecies.gov
Invasive Plant Atlas of the United States
http://www.invasiveplantatlas.org/index.html
Weeds Gone Wild: Alien Plant Invaders of Natural Areas (Alien Plant Working Group)
http://www.nps.gov/plants/alien
Because the goals and objectives of restoration projects differ from agricultural and landscaped
areas, weed control can be more specific—for example, targeting only specific invasive nonnative
weeds, and not all weeds, on a site. Generally, after controlling weeds for two to three years, the
frequency of control efforts can be significantly reduced if not discontinued.
Only the most invasive and disruptive weeds require control, thus it is sometimes possible to
accept or even encourage the presence of certain “weeds” that may have beneficial values, such
as the control of soil erosion. This is similar to the agricultural use of such weeds as wild mustard
between rows of trees in orchards.
In some instances, restoration practitioners use the technique of installing a nurse crop. A nurse
crop is not necessarily a species, native or exotic, that is appropriate to the ultimate goal of the project,
but it is an intermediate step on the way. This technique is used when faced with some type of chal-
lenge that native plants are unable to overcome in a short time period. For example, by preempting
available space for colonization, a nurse crop can provide immediate cover to discourage other exotic
“weeds” from establishing in large numbers. Nurse crops also stabilize soil; add nitrogen, if needed,
by planting annual legumes; add organic matter to the soil as the nurse crop dies; and provide tempo-
rary shade or windbreak or some other needed function quicker than native species. It is important
that you know the relationship of the nurse crop to the target species you are trying to promote. In
some situations, exotic species can get out of control and outcompete the targeted species. This is a
serious consideration you will need to evaluate prior to adopting it as a technique for use on your site.
One common goal of weed management programs for restoration project sites is to create a
mostly native groundcover that will resist invasion by nonnative weeds. This goal may be reached
by forcing the sprouting of weed seeds, which are then tilled into the soil or otherwise killed by