Wind-felled trees are a source of 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 stream are the three main providers of flow resistance, and are thus, a major influence on the shape of the stream channel.
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Large woody debris slow the flow through a bend in the stream, while accelerating flow in the constricted area downstream of the obstruction.Daniels, Melinda D; Rhoads, Bruce L "Influence of experimental removal of large woody debris on spatial patterns of three-dimensional flow in a meander bend" Earth Surface Processes and Landforms, vol.32, no.3, pp.
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The study of woody debris is important for its forestry management implications. Plantation thinning can reduce the potential for recruitment of LWD into proximal streams. The presence of large woody debris is important in the formation of pools which serve as salmon habitat in the Pacific Northwest. Entrainment of the large woody debris in a stream can also cause erosion and scouring around and under the LWD.
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The report concluded that the river could be significantly improved for trout if the hatches at Lyde Mill could be altered to lower the surface water level a little, and thus increase the water velocity. Creating areas of dappled shade by some felling of trees, particularly where they form dense cover of the river would also be beneficial, and the felled wood could be used as large woody debris, to narrow the channel and scour sediments from the bed. Large woody debris has been shown to significantly increase the range of habitats within a river.
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Substrate can also be organic and may include fine particles, autumn shed leaves, large woody debris such as submerged tree logs, moss, and semi-aquatic plants. Substrate deposition is not necessarily a permanent event, as it can be subject to large modifications during flooding events.
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A stepping stone is a morphological element that allows organisms to either migrate and settle or drift though the river section. It does not necessarily have to be a stone or a group of stones; large woody debris (LWD), roots or aquatic plants can also have a supporting effect.
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The amount of scouring and erosion is determined by the ratio of the diameter of the piece, to the depth of the stream, and the embedding and orientation of the piece. Large woody debris helps to form pools in streams which are important habitats for fish and other species.
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The river and its tributaries were often clogged with logging slash. In addition, skidding the logs over streams destroyed their protective vegetation. The streams were eventually cleared of this debris, naturally and through human efforts. Unfortunately, there is now a lack of large woody debris in the streams because of the extensive logging.
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Curran, Janet H. "Flow Resistance of Large Woody Debris in Headwater Streams of the Washington Cascades" Abstracts with Programs - Geological Society of America, vol.29, no.6, pp.315, 1997 Some stream channels have less LWD than they would naturally because of removal by watershed managers for flood control and aesthetic reasons.
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Sedimentation is reduced or removed altogether when human activities reduce sediment yields from upstream (e.g. dams and reservoirs within upland regions, sediment detention basins) or reduce the river channel's physical complexity (e.g. channelization, drainage) or disconnect river channels from adjacent floodplains and wetlands (e.g. levees, removal of beaver dams and logjams/large woody debris).
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Aquatic habitats in alluvial rivers are sculpted by the complex interplay between sediment, flow, vegetation, and woody debris. Pools provide deeper areas of relatively cool water and provide shelter for fish and other aquatic organisms. Pool habitats are improved by complex structures such as large woody debris or boulders. Riffles provide shallower, highly turbulent aquatic habitat of primarily cobbles.
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The placement of large woody debris (LWD) in streams creates pools and side channels. The pools provide habitat for aquatic organisms while the side channels help alleviate flooding. The LWD also controls the routing of sedimentation. The source of the LWD should be outside of the riparian reserve whenever possible so as not to promote erosion in the riparian reserve.
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The river becomes somewhat braided in this stretch, with numerous channel splits. There are many logs and other types of large woody debris in this part of the river, contributing to excellent salmon habitat. The final mile of the Tye has a steeper gradient with cascades alternating with deep pools. Nearly all the Tye River's tributaries are high mountains streams with steep gradients.
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The large trees 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) fall into the stream from the riparian zone, more stream habitat features are created. Carbon is added as an energy source for biota in the stream.
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In off-mainstem channels restored by beaver on the middle section of Utah's Provo River, native fish species persist even when they have been extirpated in the mainstem channel by competition from introduced non-native fish. Efforts to restore salmonid habitat in the western United States have focused primarily on establishing large woody debris in streams to slow flows and create pools for young salmonids. Research in Washington found that the average summer smolt production per beaver dam ranges from 527 to 1,174 fish, whereas the summer smolt production from a pool formed by instream large woody debris is about 6–15 individuals, suggesting that re-establishment of beaver populations would be 80 times more effective. Beaver have been discovered living in brackish water in estuarine tidal marshes where Chinook salmon (Oncorhynchus tshawytscha) densities were five times higher in beaver ponds than in neighboring areas.
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The Lac-des-Neiges old growth forest is a black spruce fir tree about . It is a forest that has not experienced any natural or anthropogenic disturbance, a rare fact because the forest north of Quebec has been exploited for more than a century. There is also the fungus Leptoporus mollis and the liverwort Anastrophyllum hellerianum which are associated with forests having large woody debris little degraded. The forest is dominated by the balsam fir (Abies balsamea).
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This compaction does not allow the water to be absorbed into the ground, so the water runs off into the stream carrying topsoil along the way. The simplification of the stream itself has also had negative effects. The large woody debris in the streams has been removed to allow for easy access to the stream and for better travel in the streams themselves. But the faster moving current erodes the stream banks, filling the stream with more sediment.
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This was followed in the earliest Kasimovian by a major, abrupt extinction of the dominant lycopsids and a change to tree fern-dominated ecosystems. This is confirmed by a recent study showing that the presence of meandering and anabranching rivers, occurrences of large woody debris, and records of log jams decrease significantly at the Moscovian-Kasimovian boundary. Rainforests were fragmented, forming shrinking 'islands' further and further apart, and in latest Kasimovian time, rainforests vanished from the fossil record.
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Bats (Myotis, Idionycteris, Lasionycteris, and Eptesicus) also use complex early seral forests because of greater insect prey as well as suitable roosts. Stand-replacing fires stimulate an increased flow of aquatic prey to terrestrial habitats, driving increases in riparian consumers. The trees killed by fire are beneficial to the ecological integrity of stream communities because they are a main source of large woody debris inputs. There is also reproduction by some forest fungi species that are restricted to burns (e.g.
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An emerging stream restoration technique is the installation of engineered log jams. Because of channelization and removal of beaver dams and woody debris, many streams lack the hydraulic complexity that is necessary to maintain bank stabilization and healthy aquatic habitats. Reintroduction of large woody debris into streams is a method that is being experimented in streams such as Lagunitas Creek in Marin County, California and Thornton Creek, in Seattle, Washington. Log jams add diversity to the water flow by creating riffles, pools, and temperature variations.
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For example, the careful placement of large woody debris was used to create diversity of stream bank habitat. The success of the wetland restoration is largely due to the establishment of these hydrogeological characteristics. The first step of restoring the floodplain was to scrape the top 12 inches of soil off in the southern area of the site, and add up to 24 inches of fill soil to the northern half of the site. Creating this slope on the site helped deter invasive species.
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The river has carried rock debris, soil and parts of trees and plants from the mountain range of Aroania (also known as Chelmos, Χελμός), to deposit it in the valley. This occurs mainly in the wet seasons of the Quaternary.In this geological time span (2,5 million years to the present) of weathering, erosion and denudation of the mountain range, the river and the river valley have shaped their modern morphology. The river was probably much larger in those days, transporting large woody debris, sand, gravel, boulders and water in bigger quantities.
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Despite the remote location of the landslide, the event had considerable socioeconomic impact. Approximately of wood was stripped away from the slopes of Capricorn Creek and Meager Creek and the Lillooet River valley bottom and either pulverized into fine organic material or transported as large woody debris into the river system. The wood was a mixture of western hemlock, amabilis and subalpine firs, western red cedar and to a lesser extent lodgepole pine and balsam poplar. The total potential loss based on the markets at the time of the event was C$8.7 million.
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The spawning migrations begin after heavy latefall or winter rains breach the sandbar at Muir Beach allowing the fish to move upstream (usually in December and January). No salmon were seen in the 2007-2008 winter run, nor the 2008-2009 winter run. Evidence points to exhaustion of smolt oversummering in the creek due to a loss of large woody debris and deep pools where young salmon can rest. Starting in 2009, the National Park Service will begin restoring Muir Beach to create a functional, self-sustaining ecosystem and improve visitor access.
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Evidence points to exhaustion of smolt oversummering in the creek due to a loss of large woody debris and deep pools where young salmon can rest. Starting in 2009, the National Park Service began restoring Muir Beach to create a functional, self- sustaining ecosystem and improve visitor access. The intervention was almost too late, since the coho only has a three-year life span. But, as of January 2010, and for the first time in three years, an estimated 45 coho swam up Redwood Creek to spawn, creating 23 redds or clusters of eggs.
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Historical logging practices, particularly widespread clear-cutting, caused severe erosion, which led to excessive sediment buildup in the river and its tributaries. In addition, large woody debris that trapped sediment was removed from the streambed to improve flows. Noyo River estuary is recognized for protection by the California Bays and Estuaries Policy.State Water Resources Control Board Water Quality Control Policy for the Enclosed Bays and Estuaries of California (1974) State of California In 1998, the river was listed as sediment impaired by the State of California North Coast Regional Water Quality Control Board.
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With the new scheme, 129 Large Woody Debris (LWD) dams (or Leaky Dams) were installed which will allow slower moving water through, but retain fast headwaters attacking the dam head. Elsewhere, 187 heather bale check dams were constructed on the various smaller streams that feed into Pickering Beck to hold more water back. Additionally, a new floodplain was created to the north east of the town in area near to the hamlet of Newbridge known as Low Hunters Bridge. This floodplain and bund storage allows for of floodwater to be retained when the beck is in peak flow or under heavy rain conditions.
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Daylighted Stream at Spanish Banks, Vancouver, B.C. Located upstream from Spanish Banks waterfront, one of the highest profile creeks in Vancouver Metro became open to salmon in 2000. In a collaborative project between Spanish Banks Streamkeepers Association and the Department of Fisheries and Oceans Canada, barriers to fish passage were removed and habitat structure was added. Spanish Banks Creek was previously diverted through a culvert underneath a parking lot, but the lower reaches of this creek have been revitalized. The banks were stabilized with riprap, large woody debris was added for habitat cover, and spawning gravels were added in appropriate areas.
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Cryptomaster behemoth is an opilionid arachnid inhabiting large woody debris and bark microhabitat in mature coniferous or mixed coniferous and hardwood forests of the central Cascade Mountains of Oregon, with all initially discovered localities in Lane County. As with the species name of the other species in the genus, C. leviathan, the specific epithet "behemoth" is derived from the name in the Hebrew language of a large beast mentioned in the Biblical Book of Job, referencing C. behemoth's large body size compared to most travunioid Laniatores. Even though of relatively large size, Cryptomaster species are difficult to find, hence the genus name suggesting that they are masters at staying hidden.
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Environmental groups have said the problems would be solved if the Schoharie, like all the other city reservoirs, had a multi-level discharge structure, allowing water to be taken from the less turbid surface as well as the cooler depths. Boater and tuber user groups depend on releases from the Portal, which can add up to to the creek's flow, to make those activities possible. Their interests also sometimes differ with the stream's angling community on the question of large woody debris (LWD), such as trees or limbs loosened from the banks during floods. Those usually come to rest in the stream, sometimes at bridge abutments, creating habitat for trout and other aquatic life but creating navigational hazards.
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Log jam on the Quinault River, Washington, United States A log jam is a naturally occurring phenomenon characterized by a dense accumulation of tree trunks and pieces of large wood across a vast section of a river, stream, or lake. ("Large wood" is commonly defined as pieces of wood more than in diameter and more than long) Log jams in rivers and streams often span the entirety of the water's surface from bank to bank. Log jams form when trees floating in the water become entangled with other trees floating in the water, or become snagged on rocks, large woody debris, or other objects anchored underwater. They can build up slowly over months or years, or they can happen instantaneously when large numbers of trees are swept into the water after natural disasters.
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There were areas where water was leaking through the banks, which have been raised historically to impound the water for milling. Such leakage poses a threat to the integrity of the bank, and this is exacerbated by the arrival of the non- native North American signal crayfish, which burrow into banks causing further erosion. A number of low weirs had been built across the stream bed, in an attempt to improve water levels, but had resulted in slower flows depositing fine silt behind them, reducing their effectiveness. The report recommended that some of them should be removed, and replaced with large woody debris on the verges of the channel, to create faster-flowing water and help to scour silt from the bed, resulting in better conditions for plants, invertebrates and fish such as trout that prefer faster flows.
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Addition of large woody debris and plantings of native willow, alder, spruce, and other wetland vegetation have attracted beaver who have built several dams, accelerating the conversion of the man-made pasture back to wetland. Coho salmon populations are already increasing on Thompson Creek, a tributary of Neawanna Creek. By using beavers to do most of the work instead of using the usual excavation and restoration techniques for wetlands mitigation, the project cost was reduced by an estimated $60,000 to $80,000. The watershed is also important habitat for Roosevelt elk (Cervus canadensis roosevelti), black tailed deer (Odocoileus hemionus), beaver (Castor canadensis), North American river otters (Lontra canadensis), northern red- legged frog (Rana aurora), and a wide range of birds, from year-round residents like great blue herons (Ardea herodias) to migrating barn and tree swallows (Hirundo rustica and Tachycineta bicolor, respectively).
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Stanford removed the Lagunita Diversion Dam and Fish Ladder on San Francisquito Creek, near Happy Hollow Lane in Menlo Park, in late 2018, improving access for salmonid spawning runs up Los Trancos Creek and also up Corte Madera Creek to Searsville Dam Historically, several dams operated by Stanford presented impassable to nearly impassable barriers to trout, and possibly, salmon spawning runs in the San Francisquito Creek watershed. Several of these dams were constructed to divert stream flows to Stanford's reservoirs, the Lagunita Diversion Dam diverted flows to Lake Lagunita, Searsville Reservoir Dam which diverts minor flows for the Stanford Golf Course, and the Los Trancos Creek Diversion Dam which diverts water to Felt Lake. A genetics study of San Francisquito Creek steelhead in 1996 found that the fish are native and not of hatchery stock. In 2006, an Aquatic Habitat Assessment and Limiting Factors Analysis commissioned by the Santa Clara Valley Water District concluded that the key factor limiting smolt production within the study area (San Francisquito Creek mainstem and Los Trancos Creek) and potentially throughout the watershed, is a lack of suitable winter refuge in deep pools and large woody debris.
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