A riparian buffer or stream buffer is a vegetated area (a " buffer strip") near a

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...

, usually

forest A forest is an ecosystem characterized by a dense ecological community, community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, ...

ed, which helps shade and partially protect the stream from the impact of adjacent

land use Land use is an umbrella term to describe what happens on a parcel of land. It concerns the benefits derived from using the land, and also the land management actions that humans carry out there. The following categories are used for land use: fo ...

s. It plays a key role in increasing

water quality Water quality refers to the chemical, physical, and biological characteristics of water based on the standards of its usage. It is most frequently used by reference to a set of standards against which compliance, generally achieved through tr ...

in associated streams,

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s, and

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s, thus providing environmental benefits. With the decline of many

aquatic ecosystems An aquatic ecosystem is an ecosystem found in and around a body of water, in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms—aquatic life—that are dependent on each other and on their environm ...

due to

agriculture Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...

riparian A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...

buffers have become a very common conservation practice aimed at increasing water quality and reducing

pollution Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...

Benefits

Riparian buffers act to intercept

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

nutrient A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...

s, and other materials in

surface runoff Surface runoff (also known as overland flow or terrestrial runoff) is the unconfined flow of water over the ground surface, in contrast to ''channel runoff'' (or ''stream flow''). It occurs when excess rainwater, stormwater, meltwater, or other ...

and reduce nutrients and other pollutants in shallow subsurface water flow. They also serve to provide

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

and

wildlife corridor A wildlife corridor, also known as a habitat corridor, or green corridor, is a designated area habitat (ecology), that connects wildlife populations that have been separated by human activities or structures, such as development, roads, or land ...

s in primarily agricultural areas. They can also be key in reducing

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

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.

Water quality benefits

Riparian buffers intercept sediment and nutrients. They counteract

eutrophication Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...

in downstream lakes and ponds which can be detrimental to aquatic habitats because of large

fish kill The term fish kill, known also as fish die-off, refers to a localized mass mortality event, mass die-off of fish populations which may also be associated with more generalized mortality of aquatic life.University of Florida. Gainesville, FL (200 ...

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 is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to th ...

and

siltation Siltation is water pollution caused by particulate terrestrial clastic material, with a particle size dominated by silt or clay. It refers both to the increased concentration of suspended sediments and to the increased accumulation (temporary o ...

of downstream lakes, ponds, and reservoirs. Siltation can greatly reduce the life span of

reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...

s and the

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...

s that create the reservoirs.

Habitat benefits

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

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

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

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

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

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 (

large woody debris Large woody debris (LWD) are the logs, sticks, branches, and other wood that falls into streams and rivers. This debris can influence the flow and the shape of the stream channel. Large woody debris, grains, and the shape of the bed of the st ...

) fall into the stream from the riparian zone, more stream habitat features are created.

Carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

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 ''Juglans nigra'', the eastern American black walnut, is a species of deciduous tree in the walnut family, Juglandaceae, native to central and eastern North America, growing mostly in riparian zones. Black walnut is susceptible to thousand can ...

and

hazelnut The hazelnut is the fruit of the hazel tree and therefore includes any of the nuts deriving from species of the genus '' Corylus'', especially the nuts of the species ''Corylus avellana''. They are also known as cobnuts or filberts according to ...

, 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.

Design

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 on each side of the stream. ;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. ;Zone 2 :Usually made up of native

shrubs A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

, this zone provides a habitat for wildlife, including nesting areas for

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

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. ;Zone 3 :This zone is important as the first line of defense against contaminants. It consists mostly of native

grass Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and spe ...

es 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. ;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 Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidder, skidding, on-site processing, and loading of trees or trunk (botany), logs onto logging truck, trucksConservation Reserve Program The Conservation Reserve Program (CRP) is a cost-share and rental payment program of the United States Department of Agriculture (USDA). Under the program, the government pays farmers to take certain agriculturally used croplands out of produc ...

(CRP), a farming assistance program in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, 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 Nebraska ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Ka ...

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.

Effectiveness

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

University of Georgia The University of Georgia (UGA or Georgia) is a Public university, public Land-grant university, land-grant research university with its main campus in Athens, Georgia, United States. Chartered in 1785, it is the oldest public university in th ...

, 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

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

in the runoff, and at least 65% of the

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

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.Durham, Sharon. "Riparian Buffers Effective." Southeast Farm Press. 4 Feb 2004. p26 But another study in 2017 did not find efficiency (or a very limiting capacity) for reducing

glyphosate Glyphosate (IUPAC name: ''N''-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by EPSP inhibitor, inhibiting the plant enzyme 5-en ...

and

AMPA α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, better known as AMPA, is a compound that is a specific agonist for the AMPA receptor, where it mimics the effects of the neurotransmitter glutamate Glutamic acid (symbol Glu or E; kn ...

leaching to streams; spontaneous herbaceous vegetation RBS is as efficient as ''

Salix Willows, also called sallows and osiers, of the genus ''Salix'', comprise around 350 species (plus numerous hybrids) of typically deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions. Most species are known ...

'' 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.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.

Long-term sustainability

After the initial installation of the riparian buffer, relatively little maintenance is needed to keep the buffer in good condition. Once the trees and grasses mature, 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 way to protect aquatic biodiversity and 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.Nebraska Association of Resources Districts (2003)
"Conservation Trees for Nebraska."
/ref> ;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. ;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.

References

External links

National Agroforestry Center (USDA)Filter Strip Design Tool (AgBufferBuilder; USDA)Extensive Riparian Buffer bibliography
{{conservation of species Agricultural soil science Agroforestry Environmental conservation Environmental soil science Environmental terminology Forest management Habitat Habitats Hydrology Riparian zone Sustainable agriculture Sustainable design Water and the environment Water pollution Articles containing video clips