Riparian buffers and their benefits
Streams are dynamic and complex systems that include the active channel as well as its floodplain or riparian zone.
Riparian zones – which are characterized by high levels of interactions between vegetation, soil and water – link terrestrial and aquatic environments. These areas have high biotic, structural and functional diversity.
Urban development and agricultural activities can negatively impact stream ecosystems. Streams draining urban lands often suffer from “urban stream syndrome,” which is characterized by flashy hydrology, elevated concentrations of nutrients and contaminants, altered morphology, decreased amounts of organic matter, and poor biotic richness. Streams draining agricultural lands can also be negatively impacted. Livestock grazing and crop production can compact soils, remove riparian vegetation, alter stream morphology, and increase pollutant loads to streams.
One way to reduce the impacts of urbanization and agriculture on stream ecosystems is through the use of riparian buffers.
Riparian buffers are vegetation zones located between water bodies such as streams and upland areas – like lawns, pastures, driveways, and roads. These buffers typically consist of three zones planted with native species. A zone of fast and slow-growing, water-tolerant trees is located adjacent to the water; a zone of shrubs is located next to the trees, and a zone of grasses and forbs next to the shrubs. Ideally, the zones are left undisturbed; however the grasses and forbs can be mowed or grazed once fully established.
Riparian buffers offer a number of ecosystems benefits related to water quality, stream bank stabilization and habitat. Riparian buffers slow and capture runoff, which can improve water quality by trapping and filtering pollutants such as sediment, nutrients, pesticides, herbicides, road salts and heavy metals.
The root systems of riparian vegetation help to stabilize stream banks by holding the soil in place. Leaves and twigs serve as a food source for aquatic bugs called benthics that live in the water and are an important part of the food web. Riparian vegetation can also provide birds and animals with fruits and nuts as well as cover.
The shade provided by the canopy of riparian vegetation helps regulate the water’s temperature by keeping it cooler during the summer months. Maintaining a cooler water temperature helps increase the dissolved oxygen level in the water, thus creating a healthier habitat.
D.J. Scully is Campbell County Extension agent for natural resources and environmental management.