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

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 stream ...

. Riparian is also the proper nomenclature for one of the terrestrial biomes 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, environmental resource management, and civil engineering because of their role in soil conservation, their habitat biodiversity, and the influence they have on fauna and aquatic ecosystems, including grasslands, woodlands, wetlands, 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 '' ripa'', meaning "

river bank Riverbank or river bank may refer to: *Bank (geography), the bank of a river Places *Riverbank, California *Riverbank, former name of Bryte, California Enterprises and organizations *Riverbank Academy, a special school in Coventry, England * Ri ...

Characteristics

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

surface runoff Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when th ...

, and erosion. They supply shelter and food for many aquatic animals and shade that limits stream temperature change. When riparian zones are damaged by construction, agriculture or silviculture, biological restoration can take place, usually by human intervention in

erosion control Erosion control is the practice of preventing or controlling wind or water erosion in agriculture, land development, coastal areas, river banks and construction. Effective erosion controls handle surface runoff and are important techniques in ...

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 wetland 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 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 ecosystems and human health. Particularly, the attenuation of

nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zer ...

or denitrification 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 meandering 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 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, increased biodiversity, and wildlife corridors, enabling aquatic and riparian organisms to move along river systems avoiding isolated communities. Riparian vegetation can also provide forage 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 A landscape is the visible features of an area of land, its landforms, and how they integrate with natural or man-made features, often considered in terms of their aesthetic appeal.''New Oxford American Dictionary''. A landscape includes the ...

irrigation by extending seasonal or perennial flows of water. Nutrients from terrestrial vegetation (e.g. plant litter 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 Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or n ...

. 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, increased runoff from urbanization, 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 Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars. Logging is the beginning of a supply chain ...

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

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

s, trees and

shrub A shrub (often also called a 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 ...

s that thrive in proximity to water.

North America

Water's edge

Herbaceous Perennial: *'' Peltandra virginica'' – Arrow Arum *''

Sagittaria lancifolia ''Sagittaria lancifolia'', the bulltongue arrowhead, is a perennial, monocot plant in the family Alismataceae, genus ''Sagittaria'', with herbaceous growth patterns. It is native to the southeastern United States. It is known from every coastal ...

'' – 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 N ...

'' – 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 fro ...

'' – Three-square Bulrush *''

Eleocharis quadrangulata ''Eleocharis quadrangulata'' is a species of spikesedge known by the common names square-stem spikerush and four-angled spikerush. It is native to eastern and central North America (from Texas and Florida north to Ontario and Massachusetts), wit ...

'' – Square-stem Spikerush *''

Eleocharis obtusa ''Eleocharis obtusa'' is a species of spikesedge known by the common name blunt spikerush. This plant is widely distributed across Canada and the United States, where it grows in wet areas such as riverbanks and moist forest floors. It is also a ...

'' – Spikerush

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 diame ...

'' – Oregon ash *'' Prunus emarginata'' – 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, Penin ...

'' – Arroyo Willow *''

Salix lucida ''Salix lucida'', the shining willow, Pacific willow, red willow, or whiplash willow, is a species of willow native to northern and western North America, occurring in wetland habitats.Jepson Flora''Salix lucida''/ref>Plants of British Columbia'' ...

'' – 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 ''Rosa pisocarpa'' is a species of rose known by the common name cluster rose or swamp rose. It is native to western North America from British Columbia to northern California, where it generally grows in moist habitats. It is a shrub sometimes f ...

'' – Swamp Rose or Cluster Rose *'' Symphoricarpos albus'' – Snowberry *''

Spiraea douglasii ''Spiraea douglasii'' is a species of flowering plant in the rose family native to western North America. Common names include hardhack, hardhack steeplebush, Douglas' spirea, douglasspirea, steeplebush, and rose spirea. Description ''Spiraea do ...

'' – 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 *''

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, Californi ...

'' – Indian Plum, Osoberry *'' Lonicera involucrata'' – Twinberry *''

Cornus stolonifera ''Cornus sericea'', the red osier or red-osier dogwood, is a species of flowering plant in the family Cornaceae, native to much of North America. It has sometimes been considered a synonym of the Asian species ''Cornus alba''. Other names includ ...

'' – Red-osier Dogwood *'' Salix spp.'' – Willows Other plants *'' Polypodium'' – Polypody Ferns *'' Polystichum'' – Sword Ferns *'' Woodwardia'' – Giant Chain Ferns *'' Pteridium'' – Goldback Ferns *'' Dryopteris'' – Wood Ferns *'' Adiantum'' – 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'' – Giant Wildrye bunchgrass *''

Melica californica ''Melica californica'' is a species of Poaceae, 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 ...

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

Asia

In Asia 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 state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

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 belon ...

'' – 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 (botany), family Fabaceae. It is an evergreen shrub native plant, native to Victoria, A ...

'' – 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 o ...

'' – Red Stem Wattle *''

Bursaria lasiophylla ''Bursaria'' is a genus of eight species of flowering plants in the family Pittosporaceae and is endemic to Australia. They are shrubs or slender trees, often with spiny branches and have simple leaves, relatively small flowers with five sepals ...

'' – 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 pal ...

'' – 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 easter ...

'' – River She-Oak *'' Eucalyptus bridgesiana'' – Apple Box *''

Eucalyptus camaldulensis ''Eucalyptus camaldulensis'', commonly known as the river red gum, is a tree that is endemic to Australia. It has smooth white or cream-coloured bark, lance-shaped or curved adult leaves, flower buds in groups of seven or nine, white flowers an ...

'' – River Red Gum *'' Eucalyptus melliodora'' – Yellow Box *'' Eucalyptus viminalis'' – Manna Gum *'' Kunzea ericoides'' – Burgan *''

Leptospermum obovatum ''Leptospermum obovatum'', commonly known as river teatree, is a species of shrub that is endemic to south-eastern continental Australia. It has egg-shaped or lance-shaped leaves that are narrower at the base, white flowers usually arranged sin ...

'' – River Tea-Tree *'' Melaleuca ericifolia'' – Swamp Paperbark

Central Europe

Typical riparian zone trees in Central Europe include: *'' Acer campestre'' – Field Maple *''

Acer pseudoplatanus ''Acer pseudoplatanus'', known as the sycamore in the British Isles and as the sycamore maple in the United States, is a species of flowering plant in the Sapindus, soapberry and lychee family Sapindaceae. It is a large deciduous, broad-leaved ...

'' – Sycamore Maple *'' Alnus glutinosa'' – 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'' – Black Poplar *'' Quercus robur'' – Pedunculate Oak *'' Salix alba'' – White Willow *'' Salix fragilis'' – Crack Willow *'' Tilia cordata'' – Small-leaved Lime *'' Ulmus laevis'' – 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 Valley of New South Wales, 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 into the flood zone. Another technique is to quickly establish

ecological succession Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades (for example, after a wildfire) or more or less. Bacteria allows for the cycling of nutrients such as ca ...

by encouraging fast-growing plants such as "weeds" ( pioneer species) to grow. These may spread along the watercourse and cause

environmental degradation Environmental degradation is the deterioration of the environment (biophysical), environment through depletion of resources such as quality of air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; an ...

, 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 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