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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]
- Riparian forests are primarily situated alongside rivers or streams, with varying degrees of proximity to the water's edge.
- These ecosystems are intimately connected with dynamic water flow and soil processes, influencing their characteristics.
- Riparian forests feature a diverse combination of elements, including:
- Mesic terrestrial vegetation (vegetation adapted to moist conditions).
- Dependent animal life, relying on the riparian environment for habitat and resources.
- Local microclimate influenced by the presence of water bodies.
- The vegetation in riparian forests exhibits a multi-layered structure.
- Moisture-dependent trees are the dominant feature, giving these forests a unique appearance, especially in savanna regions.
- These moisture-dependent trees define the landscape, accompanied by a variety of mesic understorey, shrub, and ground cover species.
- Riparian forests often host plant species that have high moisture requirements.
- The flora typically includes species native to the region, adapted to the moist conditions provided by proximity to water bodies.
In summary, riparian forests are characterized by their location along waterways, their intricate interplay with water and soil dynamics, a diverse array of vegetation layers, and a plant composition favoring moisture-dependent species.
Riparian zones dissipate stream energy. [21] The meandering curves of a river, combined with vegetation and root systems, slow the flow of water, which reduces soil erosion and flood damage. [22] Sediment is trapped, reducing suspended solids to create less turbid water, replenish soils, and build stream banks. [23] Pollutants are filtered from surface runoff, enhancing water quality via biofiltration. [3] [24] [25]
The riparian zones also provide wildlife habitat, increased biodiversity, and wildlife corridors, [26] enabling aquatic and riparian organisms to move along river systems avoiding isolated communities. [27] Riparian vegetation can also provide forage for wildlife and livestock. [23]
Riparian zones are also important for the fish that live within rivers, such as brook and charr. [28] Impacts on riparian zones can affect fish, and restoration is not always sufficient to recover fish populations. [29] [30]
They provide native landscape irrigation by extending seasonal or perennial flows of water. [31] 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. [32] The vegetation surrounding the stream helps to shade the water, mitigating water temperature changes. Thinning of riparian zones has been observed to cause increased maximum temperatures, higher fluctuations in temperature, and elevated temperatures being observed more frequently and for longer periods of time. [33] Extreme changes in water temperature can have lethal effects on fish and other organisms in the area. [32] The vegetation also contributes wood debris to streams, which is important to maintaining geomorphology. [34]
Riparian zones also act as important buffers against nutrient loss in the wake of natural disasters, such as hurricanes. [35] [36] Many of the characteristics of riparian zones that reduce the inputs of nitrogen from agricultural runoff also retain the necessary nitrogen in the ecosystem after hurricanes threaten to dilute and wash away critical nutrients. [37] [38] [39]
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. [40]
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. [41] [42]
"Riparian zones play a crucial role in preserving the vitality of streams and rivers, especially when faced with challenges stemming from catchment land use, including agricultural and urban development. These changes in land utilization can exert adverse impacts on the health of streams and rivers and, consequently, contribute to a decline in their reproductive rates."
The protection of riparian zones is often a consideration in logging operations. [43] 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. [44] 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. [45]
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. [46] In South Africa's fynbos biome, Riparian ecosystem are heavily invaded by alien woody plants. [47] Riparian plant communities along lowland streams exhibit remarkable species diversity, driven by the unique environmental gradients inherent to these ecosystems. [48]
Riparian forest can be found in Benin, West Africa. In Benin, where the savanna ecosystem prevails, "riparian forests" include various types of woodlands, such as semi-deciduous forests, dry forests, open forests, and woodland savannas. These woodlands can be found alongside rivers and streams. [49] In Nigeria, you can also discover riparian zones within the Ibadan region of Oyo state. Ibadan, one of the oldest towns in Africa, covers a total area of 3,080 square kilometers and is characterized by a network of perennial water streams that create these valuable riparian zones. [49] In the research conducted by Adeoye et al. (2012) on land use changes in Southwestern Nigeria, it was observed that 46.18 square kilometers of the area are occupied by water bodies. Additionally, most streams and rivers in this region are accompanied by riparian forests. Nevertheless, the study also identified a consistent reduction in the extent of these riparian forests over time, primarily attributed to a significant deforestation rate. [50] In Nigeria, according to Momodu et al. (2011), there has been a notable decline of about 50% in the riparian forest coverage within the period of 1978 to 2000. This reduction is primarily attributed to alterations in land use and land cover. Additionally, their research indicates that if current trends continue, the riparian forests may face further depletion, potentially leading to their complete disappearance by the year 2040. [50] Riparian zones can also be found in Cape Agulhas region of South Africa. [51] Riparian areas along South African rivers have experienced significant deterioration as a result of human activities. Similar to many other developed and developing areas worldwide, the extensive building of dams in upstream river areas and the extraction of water for irrigation purposes have led to diminished water flows and changes in the riparian environment. [8]
Herbaceous Perennial:
Herbaceous Perennial: [52] [ unreliable source? ]
In western North America and the Pacific coast, the riparian vegetation includes:
Riparian trees [53]
Riparian shrubs [53]
Other plants
In Asia there are different types of riparian vegetation, [54] but the interactions between hydrology and ecology are similar as occurs in other geographic areas. [55]
Typical riparian vegetation in temperate New South Wales, Australia include:
Typical riparian zone trees in Central Europe include:
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. [56] [57] Riparian zones can be restored through relocation (of human-made products), rehabilitation, and time. [45] 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. [58]
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. [59] Another technique is to quickly establish ecological succession by encouraging fast-growing plants such as "weeds" (pioneer species) to grow. [60] 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. [61] [62] 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. [63] Other possible approaches include control of invasive species, monitoring of herbivore activity, and cessation of human activity in a particular zone followed by natural re-vegetation. [64] Conservation efforts have also encouraged incorporating the value of ecosystem services provided by riparian zones into management plans, as these benefits have traditionally been absent in the consideration and designing of these plans. [64] [65]
A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high discharge. The soils usually consist of clays, silts, sands, and gravels deposited during floods.
A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor (anoxic) processes taking place, especially in the soils. Wetlands form a transitional zone between waterbodies and dry lands, and are different from other terrestrial or aquatic ecosystems due to their vegetation's roots having adapted to oxygen-poor waterlogged soils. They are considered among the most biologically diverse of all ecosystems, serving as habitats to a wide range of aquatic and semi-aquatic plants and animals, with often improved water quality due to plant removal of excess nutrients such as nitrates and phosphorus.
A buffer zone is a neutral zonal area that lies between two or more bodies of land, usually pertaining to countries. Depending on the type of buffer zone, it may serve to separate regions or conjoin them. Common types of buffer zones are demilitarized zones, border zones and certain restrictive easement zones and green belts. Such zones may be comprised by a sovereign state, forming a buffer state.
Freshwater ecosystems are a subset of Earth's aquatic ecosystems. They include lakes, ponds, rivers, streams, springs, bogs, and wetlands. They can be contrasted with marine ecosystems, which have a larger salt content. Freshwater habitats can be classified by different factors, including temperature, light penetration, nutrients, and vegetation. There are three basic types of freshwater ecosystems: Lentic, lotic and wetlands. Freshwater ecosystems contain 41% of the world's known fish species.
Ecological restoration, or ecosystem restoration, is the process of assisting the recovery of an ecosystem that has been degraded, damaged, destroyed or transformed. It is distinct from conservation in that it attempts to retroactively repair already damaged ecosystems rather than take preventative measures. Ecological restoration can reverse biodiversity loss, combat climate change, support the provision of ecosystem services and support local economies. The United Nations has named 2021-2030 the Decade on Ecosystem Restoration.
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 environment. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems. Freshwater ecosystems may be lentic ; lotic ; and wetlands.
Stream ecology is the scientific study of the aquatic species, their interactions with one another, and their connection with the biological, chemical, and physical processes from multiple dimensions within streams. Streams display great variability in their force and generate spatial and temporal gradients in abiotic and biotic activities. The physical strcture of stream networks show headwater systems behave different from mid-lower order systems with mean annual discharge, channel size, alluvial habitat and contributing area all key factors.
Freshwater swamp forests, or flooded forests, are forests which are inundated with freshwater, either permanently or seasonally. They normally occur along the lower reaches of rivers and around freshwater lakes. Freshwater swamp forests are found in a range of climate zones, from boreal through temperate and subtropical to tropical.
A wet meadow is a type of wetland with soils that are saturated for part or all of the growing season which prevents the growth of trees and brush. Debate exists whether a wet meadow is a type of marsh or a completely separate type of wetland. Wet prairies and wet savannas are hydrologically similar.
A buffer strip is an area of land maintained in permanent vegetation that helps to control air quality, soil quality, and water quality, along with other environmental problems, dealing primarily on land that is used in agriculture. Buffer strips trap sediment, and enhance filtration of nutrients and pesticides by slowing down surface runoff that could enter the local surface waters. The root systems of the planted vegetation in these buffers hold soil particles together which alleviate the soil of wind erosion and stabilize stream banks providing protection against substantial erosion and landslides. Farmers can also use buffer strips to square up existing crop fields to provide safety for equipment while also farming more efficiently.
A riparian buffer or stream buffer is a vegetated area near a stream, usually forested, which helps shade and partially protect the stream from the impact of adjacent land uses. It plays a key role in increasing water quality in associated streams, rivers, and lakes, thus providing environmental benefits. With the decline of many aquatic ecosystems due to agriculture, riparian buffers have become a very common conservation practice aimed at increasing water quality and reducing pollution.
Floodplain restoration is the process of fully or partially restoring a river's floodplain to its original conditions before having been affected by the construction of levees (dikes) and the draining of wetlands and marshes.
A pond is a small, still, land-based body of water formed by pooling inside a depression, either naturally or artificially. A pond is smaller than a lake and there are no official criteria distinguishing the two, although defining a pond to be less than 5 hectares in area, less than 5 metres (16 ft) in depth and with less than 30% of its area covered by emergent vegetation helps in distinguishing the ecology of ponds from those of lakes and wetlands. Ponds can be created by a wide variety of natural processes, or they can simply be isolated depressions filled by runoff, groundwater, or precipitation, or all three of these. They can be further divided into four zones: vegetation zone, open water, bottom mud and surface film. The size and depth of ponds often varies greatly with the time of year; many ponds are produced by spring flooding from rivers. Ponds are usually freshwater but may be brackish in nature. Saltwater pools, with a direct connection to the sea to maintain full salinity, may sometimes be called 'ponds' but these are normally regarded as part of the marine environment. They do not support fresh or brackish water-based organisms, and are rather tidal pools or lagoons.
Wetland conservation is aimed at protecting and preserving areas of land including marshes, swamps, bogs, and fens that are covered by water seasonally or permanently due to a variety of threats from both natural and anthropogenic hazards. Some examples of these hazards include habitat loss, pollution, and invasive species. Wetland vary widely in their salinity levels, climate zones, and surrounding geography and play a crucial role in maintaining biodiversity, ecosystem services, and support human communities. Wetlands cover at least six percent of the Earth and have become a focal issue for conservation due to the ecosystem services they provide. More than three billion people, around half the world's population, obtain their basic water needs from inland freshwater wetlands. They provide essential habitats for fish and various wildlife species, playing a vital role in purifying polluted waters and mitigating the damaging effects of floods and storms. Furthermore, they offer a diverse range of recreational activities, including fishing, hunting, photography, and wildlife observation.
Tamarix ramosissima, commonly known as saltcedarsalt cedar, or tamarisk, is a deciduous arching shrub with reddish stems, feathery, pale green foliage, and characteristic small pink flowers.
Riparian-zone restoration is the ecological restoration of riparian-zonehabitats of streams, rivers, springs, lakes, floodplains, and other hydrologic ecologies. A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the fifteen terrestrial biomes of the earth; the habitats of plant and animal communities along the margins and river banks are called riparian vegetation, characterized by aquatic plants and animals that favor them. Riparian zones are significant in ecology, environmental 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 grassland, woodland, wetland or sub-surface features such as water tables. In some regions the terms riparian woodland, riparian forest, riparian buffer zone, or riparian strip are used to characterize a riparian zone.
Freshwater acidification occurs when acidic inputs enter a body of fresh water through the weathering of rocks, invasion of acidifying gas, or by the reduction of acid anions, like sulfate and nitrate within a lake, pond, or reservoir. Freshwater acidification is primarily caused by sulfur oxides (SOx) and nitrogen oxides (NOx) entering the water from atmospheric depositions and soil leaching. Carbonic acid and dissolved carbon dioxide can also enter freshwaters, in a similar manner associated with runoff, through carbon dioxide-rich soils. Runoff that contains these compounds may incorporate acidifying hydrogen ions and inorganic aluminum, which can be toxic to marine organisms. Acid rain also contributes to freshwater acidification. A well-documented case of freshwater acidification in the Adirondack Lakes, New York, emerged in the 1970s, driven by acid rain from industrial sulfur dioxide (SO₂) and nitrogen oxide (NOₓ) emissions.
Vulnerable waters refer to geographically isolated wetlands (GIWs) and to ephemeral and intermittent streams. Ephemeral and intermittent streams are seasonally flowing and are located in headwater position. They are the outer and smallest stems of hydrological networks. Isolated wetlands are located outside floodplain and show poor surface connection to tributaries or floodplains. Geographically isolated wetlands encompass saturated depressions that are the result of fluvial, aeolian, glacial and/or coastal geomorphological processes. They may be natural landforms or the result of human interventions. Vulnerable waters represent the major proportion of river networks.
The beaver is a keystone species, increasing biodiversity in its territory through creation of ponds and wetlands. As wetlands are formed and riparian habitats enlarged, aquatic plants colonize newly available watery habitat. Insect, invertebrate, fish, mammal, and bird diversities are also expanded. Effects of beaver recolonization on native and non-native species in streams where they have been historically absent, particularly dryland streams, is not well-researched.
The ecology of Melbourne, Victoria, is a complex and dynamic system influenced by the city's geographical location, climate, and human activities. Melbourne's natural environment includes diverse ecosystems ranging from coastal heathlands to grassy woodlands, riparian forests, and wetlands. These ecosystems support a rich array of flora and fauna, many of which are unique to the region. However, urbanisation, habitat fragmentation, and the introduction of invasive species have significantly altered the city's ecological balance, leading to various conservation and restoration initiatives.
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