May 2016 Articles

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Riparian Buffers Are Important Landscape Features

Riparian Buffers Are Important Landscape Features Source: Dirk Philipp, Associate Professor - Forages, U of A Riparian buffers help maintain water quality in grassland ecosystems by filtering runoff, holding back nutrients, providing wildlife habitat and cooling water temperatures in streams. In many cases, riparian buffers also provide shade and water access points for livestock. Unfortunately, many of our riparian buffers are in bad shape and do not function as intended, so let’s review some of their important characteristics and how functionality can be enhanced. First and foremost, riparian buffers need to have a minimum of tree cover, understory vegetation and a width of at least 30 to 50 feet to be effective. In many instances, large trees are the only remaining cover, but those trees provide less protection from erosion than a combination of trees, brush and grasses to better hold soil in place and thereby protect streambanks. A riparian buffer is a progression of low-growing vegetation on the outer edges with increasing height and plant density towards the center of the buffer, where the stream is located. Maintaining this continuing increase in vegetation density is important from both soil retention and nutrient filtering perspectives. It has been shown that large amounts of nutrients, up to 80 percent, can be collected by grassy filter strips made of the usual forage grasses common to Arkansas, such tall fescue or bermudagrass. These strips can be periodically grazed without compromising riparian functionality or farm profitability. Adjacent to the grassy filter strip is brushy vegetation that provides soil stability and wildlife habitat. This part of the riparian buffer is usually the most disturbed, as the intent of providing water to livestock in an unrestricted manner can lead to various negative impacts – eroded banks, sediment loss and soil compaction. Compacted soil will retain little rainwater, and accumulated nutrients in this area are likely to be transported into the adjacent stream. Similar to the grassy outer edges of riparian buffers, the middle section can be managed so benefits are maximized while negative environmental impacts are minimized. If livestock will be watered from streams, specific watering points should be installed to protect the most vulnerable parts of a riparian buffer. This will not reduce farm income; it will in fact help manage livestock more efficiently as animals will soon return to grazing on the adjacent pastures instead of loafing and lingering in the streams. One of the most efficient, low-cost features is designated, fortified stream crossings that serve as watering location and crossing for vehicles. These crossings can be built from concrete with a few feet of adjacent coarse gravel reaching into the stream to either side to prevent animals from loafing extended periods of time. Close to the edge of the stream, large trees are the usual form of woody vegetation. In most cases, these trees have been left standing to provide shade for animals. However, if there is not sufficient understory and vegetative ground cover present, the runoff slowing capacity of this section is limited, as large trees have virtually no filtering function. Trees, however, play a large role in maintaining bank stability and holding soil in place due to expansive root systems. The maintenance of riparian buffers on livestock farms cannot be seen as a separate item from the larger issue of watershed management. Especially in fast-growing population areas, riparian buffer zones are affected by encroaching urban development that triggers high peak flows and discharges that streams running through adjacent farmland are unable to handle. I encourage landowners to seek opportunities for cost-sharing improvements to their farms with the intent of protecting riparian buffer zones. Reclaiming disturbed areas costs money, but with offerings by NRCS or Soil Conservation Districts, taxpayers from urban areas share the expenses of improving water quality on a larger scale.