Aug 1, 2017 5 min read

The typical home gardener has probably not had much experience with riparian buffers, but it’s an important subject to those interested in water conservation, wildlife habitat and land-use practices that will sustain them.

It’s a vegetated area (a “buffer strip”) near a stream that helps shade and partially protect a stream from the impact of adjacent land uses. They are often thin lines of green containing native grasses, shrubs and trees that line the stream banks.

Riparian buffers protect water quality by intercepting sediment and pollution from agricultural fields, residential lawns, roadways and other sources. This improves habitat for aquatic wildlife while providing food, cover, water and breeding areas for many other kinds of wildlife.

Traps sediment - Runoff from fields, lawns, roads is deposited in the buffer rather than being allowed to enter the stream. Trees and shrubs along a stream bank help to reduce bank erosion.

Traps nutrients and pollutants - Fertilizers that make a lawn green and lush (and make corn grow) also encourage high levels of plants and algae in a stream, which depletes oxygen levels. A good riparian buffer can remove up to 80 percent of excessive nutrient inputs.

Recharges groundwater - It can slow down runoff so that the water can filter into the soil and recharge groundwater supplies. This can help to control flooding and also maintain adequate flow during dry periods.

Provides better habitat for fish - Too much fine sediment from erosion and runoff can clog fishes gills and smother spawning sites for fish and aquatic insects. A lack of trees (shading) along the riparian zone can cause higher water temperatures, which also reduces dissolved oxygen.

Improves habitat for other wildlife - A good buffer provides food, water, shelter and breeding sites for birds, mammals, amphibians and reptiles. The larger the habitat, the greater the benefit to wildlife diversity. A riparian buffer is more valuable to wildlife if it functions as a corridor connecting additional habitat of the same type.

A riparian buffer is usually thought of as consisting of three zones. Zone 1 begins at the water’s edge, and Zones 2 and 3 move inland. Each zone has a mixture of trees, shrubs or grasses. The composition and width of each depends on the size of the water body, the adjacent and upstream land uses, the wildlife benefits desired and other factors.

Zone 1 - Starts at the stream edge and may be up to 15 feet wide. It functions to provide bank stabilization, shade and organic inputs for the stream system. It is typically planted with larger native trees and shrubs that grow fast and tolerate wet conditions.

Zone 2 - Generally in the zone of 15 to 50 feet from the stream edge. This zone is usually a managed forest or mixed forest shrubland. Native shrubs that provide a habitat for wildlife, including nesting areas for birds, are preferred. This zone also acts to slow and absorb contaminants that Zone 3 has missed. This zone is an important transition between grassland and forest.

Zone 3 -Is the zone of approximately 50 to 75 feet from the water’s edge. This zone is important as the first line of defense and serves primarily to slow water runoff and absorb contaminants before they reach the other zones. It consists mostly of native grasses, or a mix of grasses and wildflowers, when near agricultural or residential zones. It can be planted in trees and shrubs where there is not high sediment runoff. A University of Georgia study, over a nine-year period, monitored the amount of fertilizers that reached the watershed from the source of application. It found that these buffers removed at least 60 percent of the nitrogen and 65 percent of the phosphorus in the runoff. It also showed that Zone 3 was much more effective in removing contaminants than Zones 1 and 2.

Once established, riparian buffers require relatively little maintenance to keep the buffer in good condition, while having the potential to be very effective ways to protect aquatic diversity, water quality and manage water resources.

Have a question? In Washington County, call the Master Gardeners office at 724-228-6881. Follow us on Facebook. Also consult the Penn State Extension website at http//extension.psu.edu/plants/master-gardener/counties/washington for additional information.