Riparian zone

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A riparian zone or riparian area is the interface between land and a river or stream.^[2] 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".^[3]

Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth.^[4] Plant habitats and communities along the river margins and banks are called riparian vegetation, characterized by hydrophilic plants.^[5] Riparian zones are important in ecology, environmental resource management, and civil engineering^[6] because of their role in soil conservation, their habitat biodiversity, and the influence they have on terrestrial and semiaquatic fauna as well as aquatic ecosystems, including grasslands, woodlands, wetlands, and even non-vegetative areas.^[7]

Riparian zones may be natural or engineered for soil stabilization or restoration.^[8] These zones are important natural biofilters, protecting aquatic environments from excessive sedimentation, polluted surface runoff, and erosion.^[9] They supply shelter and food for many aquatic animals and shade that limits stream temperature change.^[10] When riparian zones are damaged by construction, agriculture or silviculture, biological restoration can take place, usually by human intervention in erosion control and revegetation.^[11] 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,^[12] 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".^[13]

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.^[14][15] 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.^[16] Particularly, the attenuation of nitrate or denitrification of the nitrates from fertilizer in this buffer zone is important.^[17] 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.^[18] Also in terms of carbon transport from terrestrial ecosystems to aquatic ecosystems, riparian groundwater can play an important role.^[19] 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.^[20]