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LESSON 3 • Noxious Weeds in Wilderness—
What can I do?
Students will:

identify native and nonnative plant inhabitants of their area and of the United States.
give examples of effects of introducing plant species to an area where they were notoriginally found.
identify weeds, determine why a weed is classified exotic versus noxious, and list poten-tial effects to native vegetation, wildlife, and water quality.
identify, map, and inventory weeds using a weed handbook, and develop an on-siteweed management plan.
Where did weeds come from?
Prior to the arrival of Europeans to North America the idea of weeds was unknown. Environ-
ments throughout the world have evolved simultaneously to include the geology, vegetation
and animal life from large animals to the smallest fungus. Species evolving over time cre-
ated a balance between each other and their changing environments. Every habitat pro-
vides a niche for specific types of vegetation and the animals feeding upon this rich re-
source. The balance occurs when species adhere to an unspoken set of rules that utilize the
bounties of nature without reducing the species’ ability to survive.
Europeans brought foreign plants over to this continent in the hay used to feed their ani-mals and soil was used for ballasts on the ships. Once the left over feed and animals werebrought ashore, the plants took advantage of disturbed soils and quickly spread. Sincethese plants did not evolve in the North American environment, they did not have the samecompetition from other plants for the same space. Also, the plant diseases present inEurope’s soil and the many insects that helped keep these plants from overpopulating wereabsent in their new home.
When does a plant become a weed?
Weed is a name we’ve given to any plant that is unwanted. To become a weed, a plant must
be successful enough to be a nuisance, grow quickly, and reproduce so successfully that it
crowds out native or desirable plant species in their competition for sun, water and nutrients
taken from the soil. Most plants we have identified as weeds came from other countries. Like
our native plants, they too were in balance in their old ecosystems and developed character-
istics to survive and other species kept their populations in check. Now in the new world,
they hold a competitive edge over native vegetation, since no natural predators keep them
in balance and prevent them from exploiting their new environment.
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Weeds are classified into two groups, exotic and noxious. Plant species that have been identified
as exotic weeds are not native to the ecosystem. They are usually nontoxic and under most cir-
cumstances can be removed much easier than noxious weeds (depending on how widely they are
spread). Noxious plants establish themselves in a foreign environment and attempt to out-compete
the native plants. Many are allelopathic, which means they release toxic substances into the soil
and inhibit the growth of native plants that did not evolve with a tolerance to these chemical com-
The Wilderness Act states: Wilderness should be “managed to preserve natural conditions.” Pre-
serving natural ecosystems means keeping weeds out.
WILDERNESS: a place of diversity
Wilderness is a place of diversity and balance. This balance means plants and animals are depen-
dent on each other and the ecosystems in which they live. When balance exists, each of them can
live, but none of them dominate and prevent others from living. This results in a heathy diverse
ecosystem that provides food and shelter for many different kinds of plant and animal life. This
diversity is the key to stability, and Wilderness is that place set aside for the protection and appre-
ciation of biodiversity. Wilderness provides a base-line inventory for intact ecosystems and a refer-
ence to land management practices taking place outside Wilderness. Weeds have upset the
biological balance in many Wilderness areas throughout the nation.
Prevention is the key to keeping weeds out of Wilderness and education is the most useful tool toprovide the information to Wilderness visitors. Weeds need a disturbed soil surface in order toestablish themselves in an environment. Often this occurs from impacts related to human activity.
Human-created impacts in Wilderness may come from recreational use. Also, trail building andmaintenance of existing trails create a disturbed soil surface for weeds to begin growing.
Weeds and their seeds can be transported in many different ways into the Wilderness.
While packing gear at trailheads, use special precautions to ensure you are not transporting weedseeds in or on your equipment. Hikers need to check each other for weed seed hitch hikers thatmay be attached to their gear, boots or clothing before entering the Wilderness. If you are a stockperson, shake all your manties, pick seeds from your horses’ tails and wipe all gear free of weeds.
Pack only “certified weed seed free feed” into the backcountry.
Biology Connections
Activity 1: Who Lives Here?
• access to research materials
Duration: 2 to 3 class periods
Location: classroom
Fossil remains indicate that even in prehistoric times some plant populations traveled to different
geographical regions in response to climatic and other conditions. These movements took place
over long periods of time. In some cases original plant species of an area died out and became
Natural land and water barriers have prevented some species from spreading to certain areas. Butpeople, with their sophisticated transport systems, have changed the plant populations of islandsand continents. Many plants that we take for granted as native residents of the United Statesactually were not on this continent when the first European settlers came; other original specieshave been destroyed.
Changes that once took place gradually have been accelerated by human manipulation of plantpopulations. Human beings sometimes move plants to their advantage, sometimes to their ultimatedisadvantage, with mixed results for people and the environment. Some introduction of plants tonew areas is accidental; some intended, for example, as a management strategy.
The major purpose of this activity is to acquaint students with the distinction between native andnonnative species as well as the benefits and risks involved in introducing nonnative species toareas. Students research and write reports about native and introduced plant species and conducta class “quiz” and discussion.
1. Explain the background information to your students. Then, go around the room asking each
student to guess if the plant you name is a native (indigenous) or nonnative (introduced) species to
the area of the United States it now inhabits. OPTIONAL: Get photos of each. For example:
knapweed, goats tongue, leafy spurge, hemp, dandelion, clover, & alfalfa biscuit root, Indian paint brush, mountain aster, bear grass, huckleberry, and lady slipper NOTE: Select native and nonnative species located in your area.
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2. Ask each student to choose one of these plants to research, including: What, if any, are the benefits of its presence? What, if any, are the detrimental effects of its presence? What is the history of its presence? (If introduced, include how and why it was introduced.) What regulations, if any, exist concerning this plant? (Contact Soil Conservation Service,U.S. Forest Service, Bureau of Land Management, National Park Service, U.S. Fish &Wildlife Service and state agencies).
3. Ask students to write a short research paper on their plant. Also, have each student write thename of his or her plant on a piece of paper. Collect these and use them for a native/nonnativequiz. Have the students vote “native” or “nonnative” as each name is pulled from a box. Then havethe student who did research comment on that plant. Students can direct the voting, presentationsand discussion. Were there some surprises? Plants thought to be native that turned out to beintroduced? Based on all the plants studied, do there seem to be more positive or negative effectsfrom introducing nonnative species to environments? Credit: Project WILD, “Who Lives Here”
Activity 2: Weed Management Field Trip

student handout: “Weed Names and Weed Codes,” pages 367-368.
student handout: “Noxious Weed Inventory Form,” page 369.
weed identification handbook from your region clippers, hoes, garbage bags for weed transport, work gloves fertilizer if deemed necessary by weed expert Duration: from two hours to a full day
Location: school yards, trailheads and city/county parks
Biology Connections
1. Contact local county extension services, state, federal or park weed specialists (U.S. Forest
Service, National Park Service, Bureau of Land Management, and U.S. Fish and Wildlife Service)
for assistance in planning and conducting this field trip. Prior to the field exercise students need to
be familiar with the weed management in the area of their field trip.
2. Using the weed identification handbook, students will identify and list both common and noxiousweeds. Identify the native species present and the abundance compared to weed numbers.
3. Using the student handouts “Weed Names and Weed Codes List” and the “Noxious Weed Inven-tory Form,” students will complete forms to include: documentation of location (review mappingskills), using appropriate symbols for weeds identified, weed density and distance to water. Explainto students that this is how professionals/scientists perform a survey.
4. Use photo documentation as a monitoring tool. Students will take photos of the site. Use beforeand after photos to evaluate your effectiveness.
5. Discuss the environmental effects which may be caused by weed management efforts or ifcontrols are not implemented.
6. Discuss the use of biological controls and their effectiveness in long-term weed management.
7. As recommended with the weed specialist you are working with, broadcast native seed over thedisturbed soil surface to encourage seed growth and discourage weed growth.
Evaluation / Follow-up / Extension:

Name five species that are native (indigenous) to the United States.
Name five species that nonnative (introduced) to the United States.
When plants are introduced to new areas, they can either become extinct or be successful intheir new home. What usually happens to other plants when an introduced species is success-ful? Why? List and explain four reasons why plants may be introduced to an area.
Make a visual illustration to convey some of the possible effects of introducing nonnative spe-cies into a habitat. Show “before” and “after.” Provide examples to explain your portrayal.
Research to find out if any plant species listed as threatened or endangered in your area are aresult of competition from nonnative species. Provide an example explaining how and what hashappened to the threatened or endangered plant species.
The pre/post test will allow the teacher to identify students’ knowledge base on weeds.
Students can develop a weed management plan for their backyard, school grounds, or city/county parks.
Students can study herbicide movement and effects on plants.
Conduct “Noxious Weed Pull-Ups” contest with students.
Ask students to pull weeds when they find them and report back the location to the nearestcounty conservation district, forest service, or park office.
Biology Connections

Career Options:
county extension agent, soil scientist, botanist, ecologist, Wilderness manager, scientific researcher

Montana Weed Project Teachers Handbook, Resource Education Awareness Project by GarySwant.
Noxious Weed management Short Course, Montana Weed Control Association with the coop-eration of the U.S. Forest Service and Montana State University.
Northwest Weeds, the Ugly and Beautiful Villains of Fields, Gardens, and Roadsides, RonaldJ. Taylor.
Biology Connections
Activity 2: Weed Management Field Trip
Weed Names and Weed Codes List
Common Name
Scientific Name
Biology Connections

Activity 2: Weed Management Field Trip
Weed Names and Weed Codes List continued
Common Name
Scientific Name
Credit: Weed Science Society of America Accepted Names and Weed Codes
Biology Connections
Activity 2: Weed Management Field Trip
6/sq. ft.
T.R. Section
Other Species Present:
Estimate of infestation level:
a. L = low: occasional plants/acre, less than 5 percent canopy cover b. M = moderate: widely scattered plants, 5-25% canopy cover c. H = high: more dense, 25-100% canopy cover Symbols:
Names and weed codes used to identify each weed species is provided by the Weed Sci-
ence Society of America


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