Friday February 17, 2012
Meeting with Dr. Larry Dyck
I met with Dr. Larry Dyck who works in shoreline restoration at Abernathy Park in Clemson, SC. He is a retired Clemson University professor and botanist. He shared with me the work he has done on Lake Hartwell at the park and on island 11 of Lake Keowee.
He explained that the main reason shorelines erode is because of wave action. The larger the fetch of the body of water, the greater the surface area that can be affected by wind, creating larger more powerful waves. The waves then undercut the banks, cutting away at the toe of the scarp so that the top eventually caves in. When faced with shoreline, like that of islands, that are vulnerable to the full force of waves and waves from multiple directions, rocks must be used. By using riprap and large boulders you can hope to slow down the waves and therefore limit their effect on the scarp. You can also place anti erosion cloth beneath the rock to further stabilize it.
 |
This is an example of an erosion control cloth.
Switchgrass is growing through the cloth. |
Vegetation is also planted to help stabilize the soil. Bunch grasses like switchgrass and maidencane can be used. Maidencane tolerates longer periods of saturation so it is usually planted close to the water. Switchgrass is a large, perennial grass that roots system is generally as long as or exceeds the shoot length. The roots also collect pollutants that are present in runoff. Switchgrass is a facultative, r-selected plant that is tolerant of many habitat types and soil regimes. It is also used for food and cover by many wildlife species. Water willow is a common herb that is planted. It is also browsed by wildlife. Shrubs, such as, buttonbush are often planted in areas that are frequented by beavers, as their stems readily resprout after being chewed. Silky dogwood, a short, multi-stemmed tree can be used at the waters edge along with river birch, pond and bald cypress, and other mesophytic trees. These plants can be grown from seed in a nursery and then live staked or plugged. These plants were all recommended by Dr. Dyck. Through his work he has found that these are the most beneficial and hardy.
Dr. Dyck also pointed out that you can generally tell areas that are more heavily eroded than others by the accumulation of sand. Areas that are sandy are usually not directly affected by waves. Areas such as these could be shorelines in coves or on the back sides of peninsulas and other areas facing away from the fetch. He explained that sand particles are lighter than clay particles and are carried by water. You would think that because clay particles are smaller than sand that they would be carried but clay particles hold more water and are easily compacted, which is the occasion on shorelines. When water slows down (by hitting boulders and rock for example) the sand particles are deposited onto the shore. This in turn creates more suitable soil for plants to grow in. This is the idea behind Dr. Dyck's shoreline management practices of planting trees surrounded by large boulders and riprap. He hopes that sand will accumulate within the boundary created by the boulders and this will allow other plants to colonize. This creates natural habitats that not only help stabilize the shoreline but also provide nesting areas for migrating birds, bedding areas for whitetail deer, habitat for fishes and provides ground cover and forage for other wildlife.
I would again like to thank Dr. Dyck for taking the time to show me his work and share his ideas, as they were very much appreciated!
There will be a PowerPoint coming that shows pictures I took and will explain other aspects of shoreline stabilization and its effects on wildlife.
