Maintenance is Key to a Successful Riparian Buffer

You’ve hauled the soil, you’ve purchased the plants, you’ve lined up the volunteers, and you’ve spent the day bent over with your hands in the dirt on the bank of your beloved stream, planting shrubs, live stakes, and wildflower seeds. You stand back and brush the dirt off your hands, congratulating yourself on a job well done. Success! Not yet…maintaining your riparian buffer until it becomes well established is critical to the longevity of your efforts.

A newly-planted riparian buffer is more fragile than one might realize, requiring a certain amount of maintenance during the initial growing season. Frequent inspection of a newly-planted riparian buffer is imperative, especially after large storms. The inspection should include watching for damage to fences, the formation of gullies, weed problems (especially invasive weed colonization), wildlife damage, insect and disease problems, and bank erosion. In addition, depending on the weather, the new plantings may need to be watered periodically during the first growing season. Some seedling mortality is expected; however, woody plants should be replanted within a row if more than 3-4 consecutive seedlings have died. Reseeding should occur if large bare patches are observed.

Weed control is essential for the survival and rapid growth of trees and shrubs in a buffer during the first year. In particular, any invasive weeds seen colonizing the buffer area should be immediately removed before a large stand becomes established. Weed control options include applying 4 to 6 inches of organic mulch, using weed control fabrics, and mowing. Chemical weed control techniques are not recommended in most cases because chemicals can quickly enter the water system in riparian areas. Weed control should continue until woody plants are well established, normally 2 to 3 years.

During the first year, annual weeds can be most easily controlled by mowing the grass zone to 6 inches. Mowing lower could harm plants and nesting animals. This should only be necessary once or twice during the growing season. During the second year, if weeds are a problem, mowing to 12 to 18 inches should take place once during early summer. Mowing between the rows of trees or shrubs will help control weeds in the woody zones. In some cases, prescribed burns will help control weeds and rejuvenate native grasses. During the life of the riparian buffer, tree seedlings will begin to compete with each other. In order to maintain an optimal growth rate, trees should be pruned and trimmed regularly.

Wildlife, even native wildlife such as beavers, muskrats, and deer, can be particularly problematic to newly-established riparian buffers. Muskrats and nutria (a non-native aquatic rodent similar to the muskrat) can consume vast quantities of riparian grasses and shrubs in a relatively short period of time. Beavers and deer are partial to trees and shrubs in riparian zones, with deer nibbling on fresh buds and shoots and beavers felling young and mature trees for dams and lodges. Repellants and fencing may be the best option for short-term nuisance wildlife control while the buffer is being established. If long-term control is necessary, more aggressive management techniques such as hunting, trapping, and physical exclusion methods may be necessary. The long-term management method should be tailored to the particular problem at a given site, but in general, a reduction in the local population of the nuisance animal will be required.

Over time, if the buffer is located in an area of high sediment loadings, sediments may accumulate in the buffer, creating a small berm between the buffer and the field edge. The berm will eventually prevent field runoff from flowing through the buffer and cause runoff to flow parallel to the buffer instead. Where this occurs, accumulated sediments should be removed and the area regraded and reseeded.

The best way to reduce the maintenance activities and therefore the costs of maintaining a riparian buffer is to tailor the buffer plantings to the specific needs of the site. Planting native vegetation rated for the proper climatological zone and site conditions will improve the chances of seedling survival. Incorporating wildlife-resistant, salt-resistant, flood-tolerant, shade-tolerant, and/or disease-resistant plantings can be helpful, depending on the location and function of a given buffer. For information on choosing buffer plantings, see the fact sheet, Lake and Stream Corridor Owners’ Guide for Riparian Buffer Establishment, by the Kalamazoo Forum at http://www.theforum.org/Davis/riparian.htm. For New Jersey, the following website lists native plants by physiographic region for riparian forest buffers: http://www.rce.rutgers.edu/njriparianforestbuffers/nativeALL.htm. Another good list of native plants recommended for riparian buffers, as well as planting information and a guide to native plant nurseries can be found in the appendices of the Chesapeake Bay Local Assistance Department’s Riparian Buffer Guidance Manual, at http://www.cblad.state.va.us/news_events_publications.cfm.