A riparian zone or riparian area is the interface between land and a

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...

stream A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams ...

. Riparian is also the proper nomenclature for one of the terrestrial

biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...

s of the Earth. Plant habitats and communities along the river margins and banks are called riparian vegetation, characterized by hydrophilic plants. Riparian zones are important in

ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overl ...

environmental resource management Environmental resource management is the management of the interaction and impact of human societies on the environment. It is not, as the phrase might suggest, the management of the environment itself. Environmental resources management aim ...

, and

civil engineering Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports, sewa ...

because of their role in soil conservation, their habitat

biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity'') ...

, and the influence they have on

fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is '' flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. ...

and aquatic ecosystems, including grasslands,

woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in t ...

s, or even non-vegetative areas. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a riparian zone. The word ''riparian'' is derived from

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

'' ripa'', meaning " river bank".

Characteristics

Riparian zones may be natural or engineered for soil stabilization or restoration. These zones are important natural biofilters, protecting aquatic environments from excessive

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...

ation, polluted surface runoff, and

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...

. They supply shelter and food for many

aquatic animal An aquatic animal is any animal, whether invertebrate or vertebrate, that lives in water for most or all of its lifetime. Many insects such as mosquitoes, mayflies, dragonflies and caddisflies have aquatic larvae, with winged adults. Aquatic ...

s and shade that limits stream temperature change. When riparian zones are damaged by

construction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and ...

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...

or silviculture, biological restoration can take place, usually by human intervention in erosion control and revegetation. If the area adjacent to a watercourse has standing water or saturated soil for as long as a season, it is normally termed a

because of its hydric soil characteristics. Because of their prominent role in supporting a diversity of species, riparian zones are often the subject of national protection in a biodiversity action plan. These are also known as a "plant or vegetation waste buffer". Research shows that riparian zones are instrumental in water quality improvement for both surface runoff and water flowing into streams through subsurface or

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit ...

flow. Riparian zones can play a role in lowering nitrate contamination in surface runoff, such as manure and other fertilizers from agricultural fields, that would otherwise damage

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

s and human health. Particularly, the attenuation of nitrate or

denitrification Denitrification is a microbially facilitated process where nitrate (NO3−) is reduced and ultimately produces molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products. Facultative anaerobic bacteria perform denit ...

of the nitrates from fertilizer in this buffer zone is important. The use of wetland riparian zones shows a particularly high rate of removal of nitrate entering a stream and thus has a place in agricultural management. Also in terms of carbon transport from terrestrial ecosystems to aquatic ecosystems, riparian groundwater can play an important role. As such, a distinction can be made between parts of the riparian zone that connect large parts of the landscape to streams, and riparian areas with more local groundwater contributions.

Roles and functions

Riparian zones dissipate stream energy. The

meander A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank) and deposits sediments on an inner, convex ban ...

ing curves of a river, combined with vegetation and root systems, slow the flow of water, which reduces soil erosion and flood damage. Sediment is trapped, reducing suspended solids to create less

turbid Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. Fluids c ...

water, replenish soils, and build stream banks. Pollutants are filtered from surface runoff, enhancing water quality via biofiltration. The riparian zones also provide wildlife

habitat In ecology, the term habitat summarises the array of resources, physical and 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 ...

, increased biodiversity, and wildlife corridors, enabling aquatic and riparian organisms to move along river systems avoiding isolated communities. Riparian vegetation can also provide

forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also use ...

for wildlife and livestock. Riparian zones are also important for the fish that live within rivers, such as brook and charr. Impacts on riparian zones can affect fish, and restoration is not always sufficient to recover fish populations. They provide native landscape irrigation by extending seasonal or perennial flows of water. Nutrients from terrestrial vegetation (e.g.

plant litter Plant litter (also leaf litter, tree litter, soil litter, litterfall or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that have fallen to the ground. This detritus or dead organic material and its constitue ...

and insect drop) are transferred to aquatic food webs, and are a vital source of energy in aquatic food webs. The vegetation surrounding the stream helps to shade the water, mitigating water temperature changes. Extreme changes in water temperature can have lethal effects on fish and other organisms in the area. The vegetation also contributes wood debris to streams, which is important to maintaining geomorphology. From a social aspect, riparian zones contribute to nearby property values through amenity and views, and they improve enjoyment for footpaths and bikeways through supporting foreshoreway networks. Space is created for riparian sports such as fishing, swimming, and launching for vessels and paddle craft. The riparian zone acts as a sacrificial erosion buffer to absorb impacts of factors including

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

, increased runoff from

urbanization Urbanization (or urbanisation) refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. It is predominantly th ...

, and increased boat wake without damaging structures located behind a setback zone.

Role in logging

The protection of riparian zones is often a consideration in logging operations. The undisturbed soil, soil cover, and vegetation provide shade, plant litter, and woody material, and reduce the delivery of soil eroded from the harvested area. Factors such as soil types and root structures, climatic conditions, and vegetative cover determine the effectiveness of riparian buffering. Activities associated with logging, such as sediment input, introduction or removal of species, and the input of polluted water all degrade riparian zones.

Vegetation

Willow Creek, Trout Creek Mountains, Oregon

The assortment of riparian zone trees varies from those of wetlands and typically consists of plants that are either emergent aquatic plants, or herbs, trees and shrubs that thrive in proximity to water.

North America

Water's edge

Herbaceous Perennial: *'' Peltandra virginica'' – Arrow Arum *'' Sagittaria lancifolia'' – Arrowhead *''

Carex stricta ''Carex stricta'' is a species of sedge known by the common names upright sedge and tussock sedge. The plant grows in moist marshes, forests and alongside bodies of water.

'' – Tussock Sedge *''

Iris virginica ''Iris virginica'', with the common name Virginia blueflag, Virginia iris, great blue flag, or southern blue flag, is a perennial species of flowering plant in the Iridaceae (iris) family, native to central and eastern North America. It was iden ...

'' – Southern Blue Flag Iris

Inundated riparian zone

Herbaceous Perennial: *''

Sagittaria latifolia ''Sagittaria latifolia'' is a plant found in shallow wetlands and is sometimes known as broadleaf arrowhead, duck-potato, Indian potato, katniss, or wapato. This plant produces edible tubers that have traditionally been extensively used by Nati ...

'' – Duck Potato *'' Schoenoplectus tabernaemontani'' – Softstem Bulrush *''

Scirpus americanus ''Schoenoplectus americanus'' (syn. ''Scirpus americanus'') is a species of flowering plant in the sedge family known by the common names chairmaker's bulrush and Olney's three-square bulrush. It is native to the Americas, where it is known from ...

'' – Three-square Bulrush *'' Eleocharis quadrangulata'' – Square-stem Spikerush *'' Eleocharis obtusa'' –

Spikerush ''Eleocharis'' is a virtually cosmopolitan genus of 250 or more species of flowering plants in the sedge family, Cyperaceae. The name is derived from the Greek words ἕλειος (''heleios''), meaning "marsh dweller," and χάρις (''charis' ...

Western

In western North America and the Pacific coast, the riparian vegetation includes: Riparian trees *'' Sequoia sempervirens'' – Coast Redwood *'' Thuja plicata'' – Western Redcedar *'' Abies grandis'' – Grand Fir *'' Picea sitchensis'' – Sitka Spruce *'' Chamaecyparis lawsoniana'' – Port Orford-cedar *'' Taxus brevifolia'' – Pacific Yew *'' Populus fremontii'' – Fremont Cottonwood *'' Populus trichocarpa'' – Black Cottonwood *'' Platanus racemosa'' – California Sycamore *'' Alnus rhombifolia'' – White Alder *'' Alnus rubra'' – Red Alder *'' Acer macrophyllum'' – Big-leaf Maple *''

Fraxinus latifolia ''Fraxinus latifolia'', the Oregon ash, is a member of the ash genus ''Fraxinus'', native to western North America. Description ''Fraxinus latifolia'' is a medium-sized deciduous tree that can grow to heights of in height, with a trunk diamete ...

'' – Oregon ash *''

Prunus emarginata ''Prunus emarginata'', the bitter cherry or Oregon cherry, is a species of '' Prunus'' native to western North America, from British Columbia south to Baja California, and east as far as western Wyoming and New Mexico. It is often found in re ...

'' – Bitter Cherry *''

Salix lasiolepis ''Salix lasiolepis'' (arroyo willow) is a species of willow native to western North America. Distribution The core range of the arroyo willow includes most of California, including the California Coast Ranges, Arizona, Klamath Mountains, Peni ...

'' – Arroyo Willow *'' Salix lucida'' – Pacific Willow *'' Quercus agrifolia'' – Coast live oak *'' Quercus garryana'' – Garry oak *'' Populus tremuloides'' – Quaking Aspen *'' Umbellularia californica'' – California Bay Laurel *'' Cornus nuttallii'' – Pacific Dogwood Riparian shrubs *'' Acer circinatum'' – Vine Maple *'' Ribes spp.'' – Gooseberies and Currants *'' Rosa pisocarpa'' – Swamp Rose or Cluster Rose *'' Symphoricarpos albus'' – Snowberry *'' Spiraea douglasii'' – Douglas spirea *'' Rubus spp.'' – Blackberries, Raspberries, Thimbleberry, Salmonberry *''

Rhododendron occidentale ''Rhododendron occidentale'', the western azalea or California azalea, is one of two deciduous ''Rhododendron'' species native to western North America (the other is '' Rhododendron albiflorum''). The western azalea is known to occur as far north ...

'' – Western Azalea *''

Oplopanax horridus Devil's club or devil's walking stick (''Oplopanax horridus'', Araliaceae; syn. ''Echinopanax horridus'', ''Fatsia horrida'') is a large understory shrub native to the rainforests of the Pacific Northwest, but also disjunct on islands in Lake S ...

'' – Devil's Club *''

Oemleria cerasiformis ''Oemleria cerasiformis'', a shrub commonly known as osoberry or Indian plum, is the sole species in genus ''Oemleria''. Native to the Pacific coast and ranges of North America, from British Columbia, Canada to Santa Barbara County, California ...

'' – Indian Plum, Osoberry *'' Lonicera involucrata'' – Twinberry *'' Cornus stolonifera'' – Red-osier Dogwood *'' Salix spp.'' – Willows Other plants *'' Polypodium'' – Polypody Ferns *'' Polystichum'' – Sword Ferns *'' Woodwardia'' – Giant Chain Ferns *''

Pteridium Bracken (''Pteridium'') is a genus of large, coarse ferns in the family Dennstaedtiaceae. Ferns (Pteridophyta) are vascular plants that have alternating generations, large plants that produce spores and small plants that produce sex cells (egg ...

'' – Goldback Ferns *'' Dryopteris'' – Wood Ferns *''

Adiantum ''Adiantum'' (), the maidenhair fern, is a genus of about 250 species of ferns in the subfamily Vittarioideae of the family Pteridaceae, though some researchers place it in its own family, Adiantaceae. The genus name comes from Greek, meaning "un ...

'' – Maidenhair Ferns *'' Carex spp.'' – Sedges *'' Juncus spp.'' – Rushes *''

Festuca californica ''Festuca californica'' is a species of grass known by the common name California fescue. This fescue species is native to the U.S. states of California and Oregon, where it is a member of many plant communities, including chaparral and oak wo ...

'' – California Fescue bunchgrass *''

Leymus condensatus ''Leymus condensatus'', the giant wildrye, is a wild rye grass native to eastern Oregon, California and northern Mexico. Description ''Leymus condensatus'' also commonly referred to as ''Canyon Prince'' is a type of wild rye that is part of t ...

'' – Giant Wildrye bunchgrass *''

Melica californica ''Melica californica'' is a species of grass known by the common name California melic. Distribution This grass is native to Oregon and California, where it grows in many types of habitat, from mountain forests to open grassland at sea level. D ...

'' – California Melic bunchgrass *'' Mimulus spp.'' – Monkeyflower and varieties *'' Aquilegia spp.'' – Columbine

Asia

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

there are different types of riparian vegetation, but the interactions between hydrology and ecology are similar as occurs in other geographic areas. *'' Carex spp.'' – Sedges *'' Juncus spp.'' – Rushes

Australia

Typical riparian vegetation in temperate New South Wales,

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

include: *''

Acacia melanoxylon ''Acacia melanoxylon'', commonly known as the Australian blackwood, is an ''Acacia'' species native in South eastern Australia. The species is also known as Blackwood, hickory, mudgerabah, Tasmanian blackwood, or blackwood acacia. The tree belo ...

'' – Blackwood *''

Acacia pravissima ''Acacia pravissima'', commonly known as Ovens wattle, Oven wattle, wedge-leaved wattle and Tumut wattle, is a species of flowering plant in the legume family Fabaceae. It is an evergreen shrub native to Victoria, the South West Slopes and Southe ...

'' – Ovens Wattle *''

Acacia rubida ''Acacia rubida'', commonly known as red stem wattle, red stemmed wattle or red leaved wattle, is a shrub belonging to the genus ''Acacia'' and the subgenus ''Phyllodineae'' that is native to parts of eastern Australia. Description The shrub ...

'' – Red Stem Wattle *'' Bursaria lasiophylla'' – Blackthorn *''

Callistemon citrinus ''Melaleuca citrina'', the common red bottlebrush, crimson bottlebrush, or lemon bottlebrush, is a plant in the myrtle family Myrtaceae, and is endemic to eastern Australia. Some Australian state herbaria continue to use the name ''Callistemon ...

'' – Crimson Bottlebrush *''

Callistemon sieberi ''Melaleuca paludicola'', commonly known as river bottlebrush, is a plant in the myrtle family Myrtaceae, and is endemic to eastern Australia. (Some Australian state herbaria continue to use the names ''Callistemon sieberi'' or ''Callistemon pa ...

'' – River Bottlebrush *''

Casuarina cunninghamiana ''Casuarina cunninghamiana'', commonly known as river oak or river she-oak, is a she-oak species of the genus ''Casuarina''. The native range in Australia extends from Daly River in the Northern Territory, north and east in Queensland and easte ...

'' – River She-Oak *'' Eucalyptus bridgesiana'' – Apple Box *'' Eucalyptus camaldulensis'' – River Red Gum *'' Eucalyptus melliodora'' – Yellow Box *'' Eucalyptus viminalis'' – Manna Gum *'' Kunzea ericoides'' – Burgan *'' Leptospermum obovatum'' – River Tea-Tree *'' Melaleuca ericifolia'' – Swamp Paperbark

Central Europe

Typical riparian zone trees in

Central Europe Central Europe is an area of Europe between Western Europe and Eastern Europe, based on a common historical, social and cultural identity. The Thirty Years' War (1618–1648) between Catholicism and Protestantism significantly shaped the a ...

include: *'' Acer campestre'' – Field Maple *'' Acer pseudoplatanus'' – Sycamore Maple *''

Alnus glutinosa ''Alnus glutinosa'', the common alder, black alder, European alder, European black alder, or just alder, is a species of tree in the family Betulaceae, native to most of Europe, southwest Asia and northern Africa. It thrives in wet locations ...

'' – Black Alder *''

Carpinus betulus ''Carpinus betulus'', the European or common hornbeam, is a species of tree in the birch family Betulaceae, native to Western Asia and central, eastern, and southern Europe, including southern England. It requires a warm climate for good growth, ...

'' – European Hornbeam *'' Fraxinus excelsior'' – European Ash *'' Juglans regia'' – Persian Walnut *'' Malus sylvestris'' – European Wild Apple *'' Populus alba'' – White Poplar *''

Populus nigra ''Populus nigra'', the black poplar, is a species of cottonwood poplar, the type species of section ''Aigeiros'' of the genus '' Populus'', native to Europe, southwest and central Asia, and northwest Africa.Flora Europaea''Populus nigra''/ref ...

'' – Black Poplar *'' Quercus robur'' – Pedunculate Oak *'' Salix alba'' – White Willow *'' Salix fragilis'' – Crack Willow *'' Tilia cordata'' – Small-leaved Lime *''

Ulmus laevis ''Ulmus laevis'' Pall., variously known as the European white elm, fluttering elm, spreading elm, stately elm and, in the United States, the Russian elm, is a large deciduous tree native to Europe, from France northeast to southern Finland, east b ...

'' – European White Elm *'' Ulmus minor'' – Field Elm

Repair and restoration

Land clearing followed by floods can quickly erode a riverbank, taking valuable grasses and soils downstream, and later allowing the sun to bake the land dry. Riparian zones can be restored through relocation (of man-made products), rehabilitation, and time. Natural Sequence Farming techniques have been used in the

Upper Hunter The Upper Hunter Shire is a local government area in the Upper Hunter Region of New South Wales, Australia. The Shire was formed in May 2004 from the Scone Shire and parts of Murrurundi and Merriwa shires. The Mayor of the Upper Hunter Shir ...

Valley of

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

, Australia, in an attempt to rapidly restore eroded farms to optimum productivity. The Natural Sequence Farming technique involves placing obstacles in the water's pathway to lessen the energy of a flood, and help the water to deposit soil and

seep A seep or flush is a moist or wet place where water, usually groundwater, reaches the earth's surface from an underground aquifer. Description Seeps are usually not of sufficient volume to be flowing beyond their immediate above-ground location ...

into the flood zone. Another technique is to quickly establish ecological succession by encouraging fast-growing plants such as "weeds" ( pioneer species) to grow. These may spread along the watercourse and cause environmental degradation, but may stabilize the soil, place carbon into the ground, and protect the land from drying. The weeds will improve the streambeds so that trees and grasses can return, and later ideally replace the weeds. There are several other techniques used by government and non-government agencies to address riparian and streambed degradation, ranging from the installation of bed control structures such as log sills to the use of pin groynes or rock emplacement. File:Cottonwood Creek, BLM, Oregon, 1988.jpg, alt=A rocky, brown stream bank mostly bare of vegetation, with a few aspen trees in the background, Cottonwood Creek riparian area in southeastern

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

before restoration, 1988 File:Cottonwood Creek, BLM, Oregon, 2000.jpg, alt=The same stream bank lined with short grasses, with more aspen trees in the background, Cottonwood Creek riparian area during recovery, 2000 File:Cottonwood Creek, BLM, Oregon, 2002.jpg, alt=The same stream bank lined with higher grasses that obscure most of the water, with a thicker aspen grove behind, Cottonwood Creek riparian area after restoration, 2002

References

External links

Dissertation on riparian vegetation of Chalakudy RiverNational Riparian Service Team, Bureau of Land ManagementRed River Basin Riparian ProjectRiparian Forest Buffers, Kansas State University
* {{DEFAULTSORT:Riparian Zone Terrestrial biomes Environmental conservation Hydrology Water streams Rivers Habitats Habitat Water and the environment Freshwater ecology