Appendix B: Bioengineering for Streambank Erosion Control -- Guidelines
3 Plant Acquisition And Handling
Almost all of the plants used in bioengineering can be considered wetland plants, either
obligative or facultative. Some of the exceptions would occur in the terrace zone that is
infrequently flooded; however, all must be somewhat flood-tolerant. Both herbaceous and
woody plants are used. Herbaceous plants may be emergent aquatic plants like rushes and
sedges or grasses and other forbs that require non-aquatic, but moist conditions at least part
of the year. The herbaceous plants are usually acquired as vegetative material such as sprigs,
rhizomes, and tubers. Sometimes seed is acquired, but is used when the threat of flooding is
low in the bank and terrace zones. Otherwise, they would wash out quite easily unless they
are seeded underneath or in a geotextile mat or fabric that is securely anchored.
Woody plants used for bioengineering purposes usually consist of stem cuttings, those
that quickly sprout roots and stems from the parent stem. These are plants such as willow,
some dogwood, and some alder. They can be supplemented by bare-root or containerized
stock, particularly in the bank or terrace zones where they are not subjected to frequent
flooding. Gray and Sotir (1996) list several such plants that can be used in bioengineering and
relate their flood tolerances, along with some other characteristics.
There are three suitable methods to acquire plants for bioengineering treatments. Each
has, according to Pierce (1994), noteworthy advantages, but critical disadvantages that make
plant acquisition and handling an important and complex process. The three methods are to:
a) purchase plants, b) collect plants from the wild; and c) propagate and grow plants.
Regardless of the method chosen, it is necessary to conduct the following steps (Pierce,
1994):
a.
Determine the available hydrologic regime and soil types. General positioning of
the plant type, e.g., emergent aquatic, shrubby willow, should be in accordance with
the plant zone (splash, bank, and terrace) defined in Part II.
b.
Prepare a list of common wetland plant species in the region and more preferably,
in the watershed containing the stream of concern, and match those to the
hydrology and substrate of the target streambank reach to be addressed.
c.
Select species that will match the energy of the environment and the hydraulic
conveyance constraints that may be imposed by the situation. For instance, one
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