Riparian buffer

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A riparian buffer of vegetation lining a farm creek in Story County, Iowa

A riparian buffer or stream buffer is a

conservation practice aimed at increasing water quality and reducing pollution
.

Benefits

Riparian buffers act to intercept

stream bank stabilization. Large scale results have demonstrated that the expansion of riparian buffers through the deployment of plantations systems can effectively reduce nitrogen emissions to water and soil loss by wind erosion, while simultaneously providing substantial environmental co-benefits, having limited negative effects on current agricultural production.[2]

Water quality benefits

Riparian buffers intercept sediment and nutrients. They counteract

bioaccumulate in the organism, with the chemicals reaching harmful levels once they are ready for human consumption. Riparian buffers also stabilise the bank surrounding the water body which is important since erosion can be a major problem in agricultural regions when cut (eroded) banks can take land out of production. Erosion can also lead to sedimentation and siltation of downstream lakes, ponds, and reservoirs. Siltation can greatly reduce the life span of reservoirs and the dams
that create the reservoirs.

Habitat benefits

Riparian buffers can act as crucial habitat for a large number of species, especially those who have lost

biota
in the stream.

Economic benefits

Buffers increase land value and allow for the production of profitable alternative crops. Vegetation such as

black walnut and hazelnut, which can be profitably harvested, can be incorporated into the riparian buffer. Lease fees for hunting can also be increased as the larger habitat means that the land will be more sought-after for hunting purposes. Designing buffer zones based on their hydrological function instead of a traditionally used fixed width method, can be economically beneficial in forestry practices.[3]

Design

Ground level view of riparian buffer between Munson Pond (off camera left) and an agricultural operation (off camera right), in Kelowna, British Columbia

A riparian buffer is usually split into three different zones, each having its own specific purpose for filtering runoff and interacting with the adjacent aquatic system. Buffer design is a key element in the effectiveness of the buffer. It is generally recommended that native species be chosen to plant in these three zones, with the general width of the buffer being 50 feet (15 m) on each side of the stream.[4]

Zone 1
This zone should function mainly to shade the water source and act as a bank stabilizer. The zone should include large native tree species that grow fast and can quickly act to perform these tasks. Although this is usually the smallest of the three zones and absorbs the fewest contaminants, most of the contaminants have been eliminated by Zone 2 and Zone 3.[5]
Zone 2
Usually made up of native
shrubs, this zone provides a habitat for wildlife, including nesting areas for bird species. This zone also acts to slow and absorb contaminants that Zone 3 has missed. The zone is an important transition between grassland and forest.[5]
Zone 3
This zone is important as the first line of defense against contaminants. It consists mostly of native
grasses and serves primarily to slow water runoff and begin to absorb contaminants before they reach the other zones. Although these grass strips should be one of the widest zones, they are also the easiest to install.[5]
Streambed Zone
The streambed zone of the riparian area is linked closely to Zone 1. Zone 1 provides fallen limbs, trees, and tree roots that in turn slow water flow, reducing erosional processes associated with increased water flow and flooding. This woody debris also increases habitat and cover for various aquatic species.

The US National Agroforestry Center has developed a filter strip design tool called AgBufferBuilder, which is a GIS-based computer program for designing vegetative filter strips around agricultural fields that utilizes terrain analysis to account for spatially non-uniform runoff.

Forest management

Logging is sometimes recommended as a management practice in riparian buffers, usually to provide economic incentive. However, some studies have shown that logging can harm wildlife populations, especially birds. A study by the University of Minnesota found that there was a correlation between the harvesting of timber in riparian buffers and a decline in bird populations.[6] Therefore, logging is generally discouraged as an environmental practice, and left to be done in designated logging areas.

Conservation incentives

The Conservation Reserve Program (CRP), a farming assistance program in the United States, provides many incentives to landowners to encourage them to install riparian buffers around water systems that have a high chance of non-point water pollution and are highly erodible. For example, the Nebraska system of Riparian Buffer Payments offers payments for the cost of setup, a sign up bonus, and annual rental payments.

These incentives are offered to agriculturists to compensate them for their economic loss of taking this land out of production. If the land is highly erodible and produces little economic gain, it can sometimes be more economic to take advantage of these CRP programs.[7]

Effectiveness

Riparian buffers have undergone much scrutiny about their effectiveness, resulting in thorough testing and monitoring. A study done by the

Salix plantations and measures of glyphosate in runoff after a year, suggest an unexpected persistence and even a capacity of RBS to potentially favor glyphosate infiltration up to 70 cm depth in the soil.[9][clarification needed
]

Long-term sustainability

After the initial installation of the riparian buffer, relatively little maintenance needs to be performed to keep the buffer in good condition. Once the trees and grasses reach maturity, they regenerate naturally and make a more effective buffer. The sustainability of the riparian buffer makes it extremely attractive to landowners, since they do relatively little work and still receive payments. Riparian buffers have the potential to be the most effective ways to protect aquatic biodiversity, water quality and manage water resources in developing countries that lack the funds to install water treatment and supply systems in midsize and small towns.

Species selection

Species selection based on an area in Nebraska, as an example:

In Zone 1
Cottonwood, Bur Oak, Hackberry, Swamp White Oak, Siberian Elm, Honeylocust, Silver Maple, Black Walnut, and Northern Red Oak.[10]
In Zone 2
Manchurian apricot, Silver Buffaloberry, Caragana, Black Cherry, Chokecherry, Sandcherry, Peking Cotoneaster, Midwest Crabapple, Golden Currant, Elderberry, Washington Hawthorn, American Hazel, Amur Honeysuckle, Common Lilac, Amur Maple, American Plum, and Skunkbush Sumac.[10]
In Zone 3
Western Wheatgrass, Big Bluestem, Sand Bluestem, Sideoats Grama, Blue Grama, Hairy Grama, Buffalo Grass, Sand Lovegrass, Switchgrass, Little Bluestem, Indiangrass, Prairie Cordgrass, Prairie Dropseed, Tall Dropseed, Needleandthread, Green Needlegrass.

See also

References

  1. ^ U.S. Natural Resources Conservation Service (NRCS). (2006). "National Conservation Practice Standard: Riparian Forest Buffer." Code 391. January 2006.
  2. S2CID 237310600
    .
  3. doi:10.1002/2015WR018014
    .
  4. ^ Dosskey, M.; Schultz, D.; Isenhart, T. (January 1997). "Riparian Buffers for Agricultural Land" (PDF). Agroforestry Notes. No. 3. Lincoln, NE: National Agroforestry Center, US Forest Service.
  5. ^ a b c Maryland Cooperative Extension (1998). Riparian Forest Buffer Design, Establishment, and Maintenance (Report). University of Maryland.
  6. ^ Journal of Wildlife Management; Apr 2005, Vol. 69 Issue 2, p689-698, 10p
  7. ^ University of Nebraska Cooperative Extension. "Benefits of Riparian Forest Buffers (Streamside Plantings of Trees, Shrubs and Grasses)." University Press, Lincoln, NE.
  8. ^ Durham, Sharon. "Riparian Buffers Effective." Southeast Farm Press. 4 Feb 2004. p26
  9. ^ Hénault-Ethier, L., Lucotte, M., Moingt, M., Paquet, S., Maccario, S., Smedbol, É., ... & Labrecque, M. (2017). Herbaceous or Salix miyabeana ‘SX64’narrow buffer strips as a means to minimize glyphosate and aminomethylphosphonic acid leaching from row crop fields. Science of the Total Environment, 598, 1177-1186.
  10. ^ a b Nebraska Association of Resources Districts (2003). "Conservation Trees for Nebraska."

External links

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