by Ty Fischer, Riparian Health Restoration Intern
This is part 3 of a series on the Great Lakes. To read the first part, please click here; part two is found here.
Erosion is a common problem on coastal bluffs and beaches on the Great Lakes’ coastlines. Despite the ubiquity of hardened shoreline structures in the region to manage these issues, such options are often not ideal since they are prone to failure and can disturb important natural processes and native species. Other large-scale construction projects, such as redirecting surface and groundwater runoff or regrading coastal bluffs, can be effective and less ecologically harmful than hardened shorelines but likewise tend to be costly and complex. Shoreline naturalization is one of the best options because it is relatively simple, very effective at addressing erosion concerns, and highly beneficial for the local ecosystem. In this blog post, the third and final part in a series on the Laurentian Great Lakes, we will detail a few strategies for shoreline naturalization on the coastal bluffs and beaches of the dynamic Great Lakes.
Naturalization is a very effective tool for managing erosion because the roots of vegetation reinforce the soil by adding shear strength and absorbing excess moisture, while the stems and any fallen detritus from the plants slow down the flow of surface water which helps reduce the movement of sediment (Chase et al., 2012). Furthermore, unlike hardened structures, living shorelines require very little maintenance and become more stable over time, compounding the benefits they provide for erosion control and the local ecosystem (NOAA, 2015). In some cases, other slope stabilization strategies must be employed in tandem with others to accomplish efforts to temporarily minimize the effects of lakebed downcutting or absorb wind and wave energy so the plants can take root. However, shoreline naturalization is a ubiquitous option that can benefit every coastline type. The specific approach used for these projects must account for the dynamic and harsh conditions of the Great Lakes, though, and differ between coastal bluffs and beaches due to differing slope and soil properties.
Before planting on coastal bluff areas, coir logs and coir mats – woven tubes and mats of biodegradable coconut fibers – can be staked into the surface to stabilize the soil and provide a surface for plants to root into (Widrig, 2022). For planting, multiple native species with well-mixed root networks should be used including trees, shrubs, herbaceous plants, and wildflowers. However, the arrangement of such vegetation types relative to the water is very important. Larger trees planted higher up on slopes can increase wind stress and promote the infiltration of water into the soil, which can further destabilize slopes (Keillor, Elizabeth, 2003). Therefore, tall trees should only be planted on the lower slopes, while low shrubs, grasses, and other groundcovers should instead be placed on the upper slopes. This arrangement makes the height and weight of tall trees the most useful and the least detrimental and also has the side benefit of improving views for property owners. Instead of removing existing trees on the upper and intermediate parts of the slope, some species such as northern hardwoods, willows, and aspens can be pruned using a method called ‘coppicing’ which removes some aboveground weight and redirects the energy into the root systems. This further strengthens the slope and improves views from the property (Keillor, Elizabeth, 2003). On the top of the bluff, it is optimal to leave a vegetated buffer of at least 10 ft wide (if not more), and property owners can also consider swapping typical turf grass for a more drought-resistant option with deeper root systems such as tall fescue (Salus et al., 2021).
Dynamic beaches in the Great Lakes region can generally be subdivided into three distinct areas: the beach itself, the foredune ridges which are at the back of the active beach, and the high dunes which are far taller and connect the beach area to the rest of the inland (Keillor, Elizabeth, 2003). If severely eroded, each of these areas can be rebuilt by ‘nourishing’ where sand or gravel is trucked in and distributed. However, foredune ridges and high dunes benefit the most from continually promoting the natural processes that can help rebuild them. This process can be encouraged by installing a line of fencing, and then following it with another line below as each fills up with sand, thus rebuilding the dune layer by layer (Keillor, Elizabeth, 2003). Fencing should be about 50% porous, the fence line should coincide with the natural vegetation line, and the fence should be roughly parallel with the shoreline. After this is completed, it is necessary to follow up with thorough planting to reestablish communities of native vegetation, as otherwise it will easily erode again once the fencing is removed (Keillor, Elizabeth, 2003). There are a variety of options for vegetation, but ideally, they are planted in a stepwise manner. The community should be initiated first by planting pioneer species such as marram (dune) grass, wheat grass, wild rye, and dune willows. After they have been established, other species such as sandcherry and chokecherry can be planted. Finally, after these plants have developed, cottonwood and basswood can be used to advance mature development (Keillor, Elizabeth, 2003).
Through applying these methods, shoreline owners living on coastal beaches or bluff areas will be able to restore the natural state of their shoreline and prevent erosion problems. This is only one benefit of naturalizing the shorelines, though. These plant buffers also filter out and store excess toxins and nutrients that are carried off roads into our waterways, thus preventing algae blooms and toxicity to aquatic species. Riparian habitat, the natural areas around rivers and lakes, are also called “ribbons of life” because of the incredible diversity of terrestrial and aquatic species they support; they provide critical habitat to mammals, birds, amphibians, reptiles, and even fish throughout their most important life stages. Naturalized shorelines can also add value to your property by increasing water quality in the adjacent waterway as well as improving the aesthetics of the shoreline itself (Hawes, Smith, 2005). All in all, they are a fantastic option for minimizing problems and maximizing ecosystem health and connectivity on the dynamic coastlines of the Great Lakes.
References
Chase, R., Clark, G., Edil, T., Kehew, A., Keillor, P., Mickelson, D. (2012). Stabilizing coastal slopes on the Great Lakes. University of Wisconsin Sea Grant Institute. Accessed from: file:///C:/Users/Asus/Downloads/StabilizingCoastalSlopes.pdf
Hawes E., Smith M. (2005). Riparian Buffer Zones: Functions and Recommended Widths. Yale School of Forestry and Environmental Studies. Accessed from: http://bolincreek.org/blog/wp-content/uploads/2011/11/riparian.buffers.attachment3.pdf
Keillor, P., Elizabeth, W. (2003). Living on the Coast: Protecting Investments in Shore Property on the Great Lakes. National Oceanic and Atmospheric Administration, U.S. Department of Commerce. Accessed from: https://repository.library.noaa.gov/view/noaa/45713
NOAA (2015). Guidance for Considering the Use of Living Shorelines. National Oceanic and Atmospheric Administration, U.S. Department of Commerce. Accessed from: https://www.habitatblueprint.noaa.gov/wp-content/uploads/2018/01/NOAA-Guidance-for-Considering-the-Use-of-Living-Shorelines_2015.pdf
Salus, L., Bechle, A., Clark, G., Noordyk, J., Bocsi, T., Carter, D. (2021). A Property Owner’s Guide to Protecting Your Bluff. University of Wisconsin Sea Grant Institute. Accessed from: https://ohiodnr.gov/static/documents/coastal/Wisconsin-ProtectingYourBluff.pdf
Widrig, R. (2022). Working with Nature: A Guide to Native Plants for New York’s Great Lakes Shorelines. Sea Grant New York. Accessed from: https://seagrant.suny
This blog post is part of a Climate Change toolkit, generously funded by The Catherine and Maxwell Meighen Foundation. Access the full toolkit here.