For our Glendon activity, Sandra and I set out to find native plant species which can be used in the remediation of the eroding river bank. Her blog post focuses on the abioitic factors which help to determine the fundamental niches, such as optimal water level and sun exposure. With this information we are able to choose locations which will best suit transplanted individuals. My blog post will concentrate on the biotic interactions and physical characteristics of the plants themselves (such as their root systems and maximal height), in addition to planting recommendations.
(A creek at Hagg Lake, Oregon. Courtesy of www.awanderingsoul.com)
What is bioengineering?
Bioengineering (also known as ecological engineering or “soft” engineering) is the use of natural materials and structures to stabilize soils by using proven engineering techniques 1. It can be used to remediate eroded shorelines, with the eventual goal of creating a shoreline that self-repairs, stabilizing soils and minimizing erosion and its resultant environmental effects. Erosion is a dynamically changing problem, and it is important to develop a solution that can respond to varied conditions.
Bioengineering facilitates increased biodiversity in rehabilitated sites as they allow vegetation to establish over time 2. This is expected to increase the primary production of the area, further increasing biodiversity for other species, increasing the visual appeal of the area. These techniques also have a low cost compared to other methods, as they require less heavy machinery, avoid the use of expensive building materials (such as concrete and steel), improve over time as the vegetation grows, and self repairs, lowering costs associated with maintenance 3,4.
(Courtesy of Save The Frogs!)
The Plants we Found
All of the plants chosen are perennials native to Ontario.
Cornus sericea (red osier dogwood)5 is a medium to tall shrub that can grow up to 4 m tall and 5 m wide. It grows best in damp soil, and is a common plant in the prevention and restoration of waterway bank erosion owing to the excellent soil retention of its roots. Red osier dogwood also serves as a useful windbreak. They can handle periods of dry soil, but prefer periods of soil saturation. They provide foods to a wide variety of birds and mammals including black bears, beavers, and rabbits. They are also readily browsed by deer. They are easily propagated from cuttings or as seeds from August to October.
(Cornus sericea, courtesy of Yerba Buena Nursery)
Corylus cornuta (beaked hazel)6 can grow up to 8 m tall. It is somewhat shade tolerant, and prefers open forests. It readily grows near disturbed forest edges and well-drained streamsides, and can resprout readily after fires. However, their above ground vegetation is vulnerable to repeated fires. Their nuts are edible, and are dispersed by jays, deer, red squirrels, and chipmunks. They can produce seeds after just 1 year, the most robust of which come after the plant is 3 years old.
(Corylus cornuta, courtesy of Native Plants PNW)
Panicum virgatum (switchgrass)7 is, as the name implies, a grass that can grow up to 2.7 m tall, where they act as a wind erosion barrier. This hardy plant has deep roots and grows best in average to wet soils from full sun to partial shade. The USDA considers this the most valuable grass for soil stabilization in the United States, as it is suitable in a wide variety of habitats. They provide food and cover for pheasants, quail, and rabbits. Switchgrass can be established as seeds, and grow best is protected from grazing in their first year.
(Panicum virgatum, courtesy of Eva Bauer)
Potentilla gracilis (slender cinquefoil)8 can grow up to a metre tall and is common in meadows, grasslands, roadsides, and open forests in moist to fairly dry soil. They are resistant to saline conditions and can grow in light shade to full sun. They provide nectar to bees, butterflies, and other insects, and are a popular garden plant. They are also resistant to deer herbivory. They can be easily introduced to an area by direct seeding or by transplanting during the fall or spring, and require little maintenance.
(Potentilla gracilis, courtesy of Go Botany)
Rhus typhina (staghorn sumac)9 is a large shrub that can grow 5 or even 10 m tall to 6 m wide. They can grow in a wide range of soil conditions, including dry and poor soils that other plants cannot tolerate. They have an extensive lateral root system that can spread more than 1 m per year. This plant grows poorly in closed canopies or near weedy non-natives. It grows well in disturbed areas, making it a good choice along the edge of the river bank. They are a popular ornamental and serve as a secondary food source in the winter for certain birds, as well as deer, rabbits, and some species of squirrels. They are best transplanted as 1 year old seedlings, as they are vulnerable in their first year of growth.
(Rhus typhina, courtesy of Evermotion)
Salix lucida (shining willow)10 can reach mature heights of between 4 and 11 m. It has a dense root matrix, making it a good filter of pollutants and sediment in riparian zones. They also can absorb floodwaters and dissipate them over time. They do best when grown away from non-native species, and when protected from grazers. The shining willow is fairly resistant to pruning by beavers and rabbits. This plant roots freely from cuttings and is easy to propagate, though it is often introduced as a sapling.
(Salix lucida, courtesy of The World Botanical Associates)
Spartina pectinata (cordgrass)11 develops sturdy stems which allow it to grow up to 3 m tall, with roots up to 3 m deep. Gardeners complain about how hard these are to dig out and how quickly the spread, perfect for our purposes! As a facultative wetland species, they can thrive in a variety of habitats. They are tolerant of water and have dense root networks, and, with their stiff stems and vigorous rhizomes make good shoreline cover, especially near fast moving water. Their morphology allows them to dissipate wave energy, making them good riparian buffers. This plant can tolerate alkaline conditions and high water tables for short periods of time. They provide cover for game birds, song birds, and small mammals. They are seeded in the spring, and do not require nitrogen fertilizer.
(Spartina pectinata, courtesy of Astrid’s Garden Design)
(courtesy of Pana Jan, Tumblr)
Thanks for reading!
1 Allen, H.H. Leech, J.R. 1997. Bioengineering for Streambank Erosion Control. U.S. Army Corps of Engineers [Online]. Available from: http://www.engr.colostate.edu/~bbledsoe/CIVE413/Bioengineering_for_Streambank_Erosion_Control_report1.pdf [Viewed: December 1st, 1016].
2 Kosiw, M. Parks, K. Besley S. 2008. Solutions to riverbank erosion: a summary of current shoreline stabilization techniques for the Gull River in Minden, Ontario. [Online]. Available from: http://www.haliburtoncooperative.on.ca/literature/sites/default/files/TP-584_Solutions_to_Riverbank_Erosion.pdf [Viewed: December 1st, 1016].
3 Lewis, L. 2000. Soil Bioengineering an alternative for roadside management: A practical guide. San Dimas Technology & Development Center. San Dimas, California. 1-47.
4 Great Lakes Sustainability Fund. 2004. [Online]. Available from: http://sustainabilityfund.gc.ca [Viewed: December 1st, 1016].
5 Stevens, M. Anderson, M. K. 2002. Plant fact sheet for red osier dogwood (Cornus sericea L.). USDA-Natural Resources Conservation Service, Corvallis Plant Materials Center, Corvallis, OR.
6 Nesom, G. 2000. Plant fact sheet for beaked hazel (Corylus cornuta Marsh.). USDA-Natural Resources Conservation Service, Corvallis Plant Materials Center, Corvallis, OR.
7 Gallon, H. 2005. Plant fact sheet for switchgrass (Panicum virgatum L.). USDA-Natural Resources Conservation Service, Corvallis Plant Materials Center, Corvallis, OR.
8 Young-Mathews, A. 2012. Plant fact sheet for slender cinquefoil (Potentilla gracilis). USDA-Natrual Resources Conservation Service, Corvallis Plant Materials Center, Corvallis, OR.
9 Gallon, H. 2002. Plant fact sheet for staghorn sumac (Rhus hirta L.). USDA-Natural Resources Conservation Service, Corvallis Plant Materials Center, Corvallis, OR.
10 Anderson, K. M. 2003. Plant fact sheet for shining willow (Salix lucida Muhl.). USDA-Natural Resources Conservation Service, Corvallis Plant Materials Center, Corvallis, OR.
11 Bush, T. 2006. Plant fact sheet for Prairie cordgrass (Spartina pectinata Bosc ex Link). USDA-Natural Resources Conservation Service, Corvallis Plant Materials Center, Corvallis, OR.