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{{Short description|Vegetated area near a stream, usually forested}}
[[File:Riparian buffer on Bear Creek in Story County, Iowa.JPG|thumb|right|A riparian buffer of vegetation lining a farm creek in Story County, Iowa]]
A '''riparian buffer''' or '''stream buffer''' is a [[Biology:Vegetation|vegetated]] area (a "[[Biology:Buffer strip|buffer strip]]") near a [[Earth:Stream|stream]], usually [[Earth:Forest|forest]]ed, which helps shade and partially protect the stream from the impact of adjacent land uses. It plays a key role in increasing [[Earth:Water quality|water quality]] in associated streams, [[Earth:River|river]]s, and [[Earth:Lake|lake]]s, thus providing environmental benefits.  With the decline of many aquatic ecosystems due to [[Earth:Agriculture|agriculture]], [[Earth:Riparian zone|riparian]] buffers have become a very common conservation practice aimed at increasing water quality and reducing [[Earth:Water pollution|pollution]].

== Benefits ==
Riparian buffers act to intercept [[Earth:Sediment|sediment]], [[Earth:Nutrient|nutrient]]s, [[Biology:Pesticide|pesticide]]s, and other materials in [[Earth:Surface runoff|surface runoff]] and reduce nutrients and other pollutants in shallow [[Earth:Subsurface flow|subsurface water flow]].<ref>U.S. Natural Resources Conservation Service (NRCS). (2006).
[ftp://ftp-fc.sc.egov.usda.gov/NHQ/practice-standards/standards/391.pdf "National Conservation Practice Standard: Riparian Forest Buffer."] Code 391. January 2006.</ref> They also serve to provide [[Earth:Habitat|habitat]] and [[Biology:Wildlife corridor|wildlife corridor]]s in primarily agricultural areas. They can also be key in reducing [[Earth:Erosion|erosion]] by providing 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.<ref>{{cite journal |last1=Englund |first1=Oskar |last2=Börjesson |first2=Pål |last3=Mola-Yudego |first3=Blas |last4=Berndes |first4=Göran |last5=Dimitriou |first5=Ioannis |last6=Cederberg |first6=Christel |last7=Scarlat |first7=Nicolae |title=Strategic deployment of riparian buffers and windbreaks in Europe can co-deliver biomass and environmental benefits |journal=Communications Earth & Environment |date=2021 |volume=2 |issue=1 |page=176 |doi=10.1038/s43247-021-00247-y |bibcode=2021ComEE...2..176E |s2cid=237310600 |doi-access=free }}</ref>

=== Water quality benefits ===
Riparian buffers intercept sediment and nutrients. They counteract [[Earth:Eutrophication|eutrophication]] in downstream lakes and ponds which can be detrimental to aquatic habitats because of large [[Earth:Fish kill|fish kill]]s that occur upon large-scale eutrophication. Riparian buffers keep chemicals, like pesticides, that can be harmful to aquatic life out of the water.  Some pesticides can be especially harmful if they 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|sedimentation]] and [[Earth:Siltation|siltation]] of downstream lakes, ponds, and reservoirs. Siltation can greatly reduce the life span of [[Earth:Reservoir|reservoir]]s 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 [[Earth:Habitat|habitat]] due to agricultural land being put into production. The habitat provided by the buffers also double as corridors for species that have had their habitat fragmented by various land uses. By adding this vegetated area of land near a water source, it increases [[Biology:Biodiversity|biodiversity]] by allowing species an area to re-establish after being displaced due to non-conservation land use.  With this re-establishment, the number of native species and biodiversity in general can be increased. The large [[Earth:Tree|tree]]s in the first zone of the riparian buffer provide shade and therefore cooling for the water, increasing productivity and increasing habitat quality for aquatic species. When branches and stumps ([[Earth:Large woody debris|large woody debris]]) fall into the stream from the riparian zone, more stream habitat features are created. [[Chemistry:Carbon|Carbon]] is added as an energy source for 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 [[Biology:Hazelnut|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.<ref>{{cite journal |last1=Tiwari |first1=T. |last2=Lundström |first2=J. |last3=Kuglerová |first3=L. |last4=Laudon |first4=H. |last5=Öhman |first5=K. |last6=Ågren |first6=A. M. |title=Cost of riparian buffer zones: A comparison of hydrologically adapted site-specific riparian buffers with traditional fixed widths |journal=Water Resources Research |date=February 2016 |volume=52 |issue=2 |pages=1056–1069 |doi=10.1002/2015WR018014|bibcode=2016WRR....52.1056T |doi-access=free }}</ref>

== Design ==
[[File:Late Winter Afternoon in Munson Park Wetlands.webm|thumb|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 {{convert|50|ft|m}} on each side of the stream.<ref>{{cite newsletter|last1=Dosskey |first1=M. |last2=Schultz |first2=D. |last3=Isenhart |first3=T. |title=Riparian Buffers for Agricultural Land |url=https://fs.usda.gov/nac/documents/agroforestrynotes/an03rfb02.pdf |date=January 1997 |work=Agroforestry Notes |issue=3 |publisher=National Agroforestry Center, US Forest Service |location=Lincoln, NE}}</ref>

;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.<ref name="Maryland Cooperative Extension 1998">{{cite report |author=Maryland Cooperative Extension |title=Riparian Forest Buffer Design, Establishment, and Maintenance |publisher=University of Maryland |date=1998}}</ref>

;Zone 2
:Usually made up of native shrubs, this zone provides a habitat for wildlife, including nesting areas for [[Biology:Bird|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.<ref name="Maryland Cooperative Extension 1998"/>

;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.<ref name="Maryland Cooperative Extension 1998"/>

;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.<ref>Journal of Wildlife Management; Apr 2005, Vol. 69 Issue 2, p689-698, 10p</ref> 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 {{wipe|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.<ref>University of Nebraska Cooperative Extension. "Benefits of Riparian Forest Buffers (Streamside Plantings of Trees, Shrubs and Grasses)."  University Press, Lincoln, NE.</ref>

== Effectiveness ==
Riparian buffers have undergone much scrutiny about their effectiveness, resulting in thorough testing and monitoring.  A study done by the [[Organization:University of Georgia|University of Georgia]], conducted over a nine-year period, monitored the amounts of fertilizers that reached the watershed from the source of the application.  It found that these buffers removed at least 60% of the [[Chemistry:Nitrogen|nitrogen]] in the runoff, and at least 65% of the [[Chemistry:Phosphorus|phosphorus]] from the fertilizer application.   The same study showed that the effectiveness of the Zone 3 was much greater than that of both Zone 1 and 2 at removing contaminants.<ref>Durham, Sharon. "Riparian Buffers Effective."  Southeast Farm Press. 4 Feb 2004. p26</ref> But another study in 2017 did not find efficiency (or a very limiting capacity) for reducing [[Chemistry:Glyphosate|glyphosate]] and [[Chemistry:AMPA|AMPA]] leaching to streams; spontaneous herbaceous vegetation RBS is as efficient as ''[[Biology:Salix|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&nbsp;cm depth in the soil.<ref name=study2017effic>Hénault-Ethier, L., Lucotte, M., Moingt, M., Paquet, S., Maccario, S., Smedbol, É., ... & Labrecque, M. (2017). ''[https://www.sciencedirect.com/science/article/pii/S0048969717309397#f0030 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.</ref>{{Clarify|reason=This does not give context on what is being discussed—specifically, what is spontaneous herbaceous vegetation and RBS?|date=October 2019}}

== 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.<ref name="NRDTree">Nebraska Association of Resources Districts (2003). [http://www.nrdnet.org/trees/pdfs/tree_book.pdf "Conservation Trees for Nebraska."]</ref>

;In Zone 2
: [[Biology:Prunus mandshurica|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.<ref name="NRDTree" />

;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 ==
{{div col|colwidth=22em}}
*[[Earth:Agricultural wastewater treatment|Agricultural wastewater treatment]]
*Agroforestry
*Ecoscaping
*[[Earth:Erosion control|Erosion control]]
*[[Earth:Nonpoint source pollution|Nonpoint source pollution]]
{{div col end}}

== References ==
{{Reflist|30em}}

== External links ==
*[https://www.fs.usda.gov/nac/practices/riparianforestbuffers.shtml National Agroforestry Center (USDA)]
*[https://www.fs.usda.gov/nac/resources/tools/AgBufferBuilder.shtml Filter Strip Design Tool (AgBufferBuilder; USDA)]
*[https://www.fs.usda.gov/nac/resources/tools/riparian-bibliography.shtml Extensive Riparian Buffer bibliography]


[[Category:Agricultural soil science]]
[[Category:Environmental soil science]]
[[Category:Environmental terminology]]
[[Category:Habitat]]
[[Category:Habitats]]
[[Category:Hydrology]]
[[Category:Water and the environment]]
[[Category:Water pollution]]

{{Sourceattribution|Riparian buffer}}