The Joyful Botanist: More dirt on soil
Native shrubs like this viburnum are great at holding soil along creeks and rivers.
Adam Bigelow photo
Plants grow in soil. It is plant roots that hold soil in the ground in fields and forests, and along creekbanks, streambanks and riverbanks. When floods come again — and they will — having plants like shrubs, trees and wildflowers growing along and up to the waterline will help ensure that the banks do not fail.
If you mow and clear plants right up to the water’s edge so that you can see the water, you are at increased risk of soil erosion and destabilizing the bank.
Soil erosion and the loss of topsoil is the primary environmental harm that occurs in Western North Carolina. During a normal or excessive rain event, the waterways around us are filled with mud and sediment, making the normally clear water run dirty, with the color and consistency of a chocolatey Yoohoo beverage. And that’s not how they’re supposed to look.
During the same storm event, you can go into the Smokies and see the creeks and rivers raging with white foam and lots of energy, but the water is clear still. That is because there is no development or other disturbances upstream and especially because there are plants along the banks, holding in the soil and helping to soak up excess water. This is how it is supposed to be.
And this is how we can all help heal the land and reduce soil erosion and sedimentation in the watershed. If you mow and clear plants along the waterways on your property, I am begging you to please stop. If your property has been cleared for a long time and the only thing that grows when you stop mowing is turfgrass, then you’ll need native plants to help hold in the soil. Turfgrass will not put roots down far enough to be effective, as the fibrous roots of mown grass only grow as deep into the soil as the height the grass blades are mown, which is usually not very much.
Roots of native wildflowers, shrubs and trees grow much deeper and are more effective at holding the soil in the ground and on the banks. Where a mowed lawn will only have roots to four or six inches into the soil, depending on how short it is mown, some native plant species can have roots as deep as 15 feet.
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If you are hoping to repair a damaged streambank and don’t have unlimited funds to buy plants, then a great approach is to use the live-stake method of establishment. Branches of native shrubs are cut in the winter when they’re dormant and then hammered or poked into the ground along the streambanks. These seemingly bare sticks will recognize that they are in soil and begin to make roots and grow into a new plant come springtime.
This works best with native shrubs like elder (Sambucus canadensis), hazel-alder (Alnus serrulata), silky willow (Salix sericea), buttonbush (Cephalanthus occidentalis), ninebark (Physocoarpus occidentalis), arrowwood viburnum (Viburnum dentatum) and silky dogwood (Swida amomum). All of these shrubs can be found growing naturally in riparian areas, and they all have the ability to form new roots along their stems when the stems come in contact with soil. This is what makes them great candidates for use in live-staking. You can also use this technique with the common riverine tree sycamore (Platanus occidentalis).
I hope you can see the benefit in not being able to see the water on your property go by and keeping the riparian area filled with plants. It will reduce soil erosion and help protect the many critters that live in the rivers and require clear, clean water to live. Things like hellbenders, trout, caddisflies, mussels and many other animals that live in the waters of WNC depend on cool clear water to live.
(The Joyful Botanist leads weekly wildflower walks most Fridays and offers consultations and private group tours through Bigelow’s Botanical Excursions. This email address is being protected from spambots. You need JavaScript enabled to view it..)
