Roadside Revegetation

PLANNING PHASE TWO: ASSESS SITE
Assessment Protocol (I-Rank) is another source of information on nonnative plants in the U.S.
(www.natureserve.org/explorer). This website describes some of the important characteristics
of the weed species and ranks each on its threat to native plant communities and difficulty
of control.
The questions to answer for each important weed species include the following:
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Life form
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How it reproduces
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Longevity of propagule
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Propagation period
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Distance of propagule spread
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Optimum growth habitat
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Aggressiveness (Figure 5-64)
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Life cycle
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Weed establishment needs
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Light needs
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Importance for pollinators
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Treatment options
From this information a strategy can be developed for each weed species that addresses
how to reduce the weed source, how to limit the optimum growing environment, and how
to control the weed species if it becomes present.
Weed Sources – How to Limit
Photo: Sally Long, Dorena Genetic Resource Center.
Figure 5-64 | Invasive species
Invasive plants such as Himalayan
blackberry [Rubus discolor (Weihe &
Nees)] (left) and Scotch broom [Cytisus
scoparius (L.) Link] (right) are aggressive
colonizers of disturbed sites such as
roadsides.
Control of weeds falls into two categories – prevention and treatment. Preventing the
introduction of a weed species is always the preferred strategy because it is easier and more
economical to prevent the introduction than to control or eliminate weeds once they have
become established. There are many possible entry points for weeds, such as the following:
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Local weed populations – Locate weed populations early in the planning phases. Early
detection and rapid response are critical to preventing weed infestation. Identify and
treat new patches before they spread (Sheley 2005). Assess weed populations in areas
adjacent to the project and work with neighboring landowners to control specific weeds.
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Vehicles and equipment – Portable wash stations are often set up to thoroughly wash
the tires, wheel wells, and chassis of vehicles and equipment to eliminate the possibility
that weed seeds are brought in from other projects or areas.
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Erosion control seeding – Rye grasses are non-native and commonly used for temporary
or permanent erosion control seeding and often in fill material for wattles. These grasses
persist in the landscape and are difficult to eradicate once introduced. Using native
grasses, or sterile hybrid grass seeds in erosion control mixes can eliminate that issue.
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Hydroseeding tanks, range drills, and other seed delivery systems – Unless
equipment is brand new, seed delivery systems have been used at other projects and
can contain plant species that are not wanted on the next site. A thorough cleaning and
inspection of this equipment are essential in eliminating the potential introduction of
undesirable plant materials. Hydroseeding tanks must be washed out and range drills
air-blown before entering the project site.
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Commercial seed sources – Commercial grass and forb seed sources, whether native
or non-native, can contain weed seeds that were harvested along with the native seeds.
The quantity of this material is dependent on the weed control practices and seed
Roadside Revegetation: An Integrated Approach to Establishing Native Plants and Pollinator Habitat
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