Large Wood Volume and Longitudinal Distribution in Channel Segments Draining Catchments with Different Land Use, Chile

Although the presence of large wood (LW) has long been recognized to enhance watershed function, land use impact on LW remains poorly understood. Using a series of six watersheds, we investigate the relationships between LW recruitment zones, LW size, and LW jam occurrence and land use. Although the results in general show urban land use to severely limit LW, they also stress that agricultural land use may be positively correlated to LW. Occurrence of potentially productive LW recruitment zones is nevertheless best correlated to total forest land cover and forested riparian area. However, the lack of mature forest due to previous widespread deforestation linked to historical agricultural land use is likely a limiting legacy effect. Since the pattern of land use seen in the study area is typical of much of the developed world, our results suggest the limiting of LW may be a major way in which watersheds are impacted in many regions. Accordingly, reintroduction of LW represents a significant opportunity to restore watersheds on a broad scale. Specifically, we propose a mix of passive conservation and active restoration of LW sources and that the targeting of these tactics be planned using the spatial analysis methods of this study.

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Historical changes in the distribution and functions of large wood in Puget Lowland rivers

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f01-199 ◽

2002 ◽

Vol 59 (1) ◽

pp. 66-76 ◽

Cited By ~ 92

Author(s):

Brian D Collins ◽

David R Montgomery ◽

Andrew D Haas

Keyword(s):

Land Use ◽

Field Data ◽

Field Studies ◽

Archival Data ◽

Large Wood ◽

Valley Bottom ◽

Lowland Rivers ◽

European Settlement ◽

River Pattern ◽

Channel Unit

We examined changes in wood abundance and functions in Puget Lowland rivers from the last ~150 years of land use by comparing field data from an 11-km-long protected reach of the Nisqually River with field data from the Snohomish and Stillaguamish rivers and with archival data from several Puget Lowland rivers. Current wood abundance is one to two orders of magnitude less than before European settlement in the Snohomish and Stillaguamish basins. Most importantly, wood jams are now rare because of a lack of very large wood that can function as key pieces and low rates of wood recruitment. These changes in wood abundance and size appear to have fundamentally changed the morphology, dynamics, and habitat abundance and characteristics of lowland rivers across scales from channel unit to valley bottom. Based on our field studies, rivers had substantially more and deeper pools historically. Archival data and field studies indicate that wood jams were integral to creating and maintaining a dynamic, anastomosing river pattern with numerous floodplain channels and abundant edge habitat and routed floodwaters and sediment onto floodplains. Establishing the condition of the riverine landscape before European settlement sets a reference against which to evaluate contemporary conditions and develop restoration objectives.

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Large wood and stream longitudinal disconnectivity

10.5194/egusphere-egu2020-10411 ◽

2020 ◽

Author(s):

Ellen Wohl ◽

Julianne Scamardo ◽

Emily Iskin

Keyword(s):

Hyporheic Exchange ◽

Longitudinal Distribution ◽

Exchange Flow ◽

Large Wood ◽

Ecological Processes ◽

Southern Rocky Mountains ◽

Longitudinal Connectivity ◽

Overbank Flow ◽

Floodplain Development ◽

Major Floods

<p>Large wood historically influenced diverse geomorphic and ecological processes in channels from first-order streams to major rivers. Centuries of deforestation and wood removal from channels have significantly reduced the presence of wood. The presence of large wood tends to decrease longitudinal connectivity, but increases lateral and vertical connectivity that arises from the presence of wood as an obstacle in the channel. Channel-spanning logjams, in particular, enhance vertical connectivity via hyporheic exchange flow and lateral connectivity via overbank flow, channel avulsion, lateral channel migration, or formation of secondary channels. In mountain streams, these effects are likely to be more pronounced in relatively wide, low gradient reaches with thicker alluvium and greater space for floodplain development and channel lateral mobility. River restoration increasingly includes maintaining or reintroducing large wood to channels, but there are relatively few studies that can be used to constrain management targets by providing data on instream large wood loads in unmanaged streams in diverse geographic settings. Here, we document the longitudinal distribution and persistence of logjams in the US Southern Rocky Mountains over a period of a decade. Key results include: (1) The longitudinal distribution of logjams varies significantly between successive stream reaches. Reaches are hundreds to thousands of meters in length and defined based on consistent stream gradient and channel lateral confinement. (2) Individual logjams change on an annual basis and typically persist less than a decade, although new logjams form frequently. (3) Individual logjams are more persistent in wide, low gradient reaches. (4) The population of logjams within a reach is more resilient to major floods in wide, low gradient reaches. The continuing breakup of jams and formation of new jams underscores the importance of ongoing wood recruitment in a natural river corridor. The results also imply that large wood reintroduction may be most effectively focused on specific types of wood process domains where the persistence and geomorphic effects of large wood are enhanced.</p>

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Longitudinal distribution and parameters of large wood in a Mediterranean ephemeral stream

Geomorphology ◽

10.1016/j.geomorph.2018.03.007 ◽

2018 ◽

Vol 310 ◽

pp. 15-28 ◽

Cited By ~ 7

Author(s):

T. Galia ◽

V. Škarpich ◽

R. Tichavský ◽

L. Vardakas ◽

K. Šilhán

Keyword(s):

Longitudinal Distribution ◽

Large Wood ◽

Ephemeral Stream

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Using a terrestrial laser scanner to detect wood characteristics in gravel-bed rivers

Journal of Agricultural Engineering ◽

10.4081/jae.2014.431 ◽

2014 ◽

Vol 45 (4) ◽

pp. 161 ◽

Cited By ~ 6

Author(s):

Alessia Tonon ◽

Lorenzo Picco ◽

Diego Ravazzolo ◽

Mario Aristide Lenzi

Keyword(s):

Laser Scanner ◽

Field Measurements ◽

Relative Difference ◽

Spatial And Temporal Variation ◽

Terrestrial Laser Scanner ◽

Large Wood ◽

Wood Volume ◽

Manual Method ◽

Margin Of Error ◽

Reliable Quantification

The possibility of analysing the characteristics and volume of inchannel large wood (LW) is of importance for river management but the traditional manual field activities are usually time-consuming and not easy to apply at a larger spatial scale. This paper presents an alternative and faster method to detect the characteristics and measurements of large wood in rivers by using the terrestrial laser scanner (TLS) technology. Field-measurements data and TLS scans were collected in August 2013 along 14 ha of the Piave River (Italy) analysing 230 and 208 woody elements for the manual method and the TLS one, respectively. TLS data were processed using the Cyclone 7 software and the LW measurements were extracted adopting two specific tools. The resulting low margin of error in the comparison between field data and those derived from TLS surveys confirmed the ability of TLS in the detection of large wood and wood jams characteristics. The greatest deviations were found for wood jams height which the TLS showed a tendency to overestimate (+24.37%) and LW length with a slight underestimation (–19.76%). Considering the wood volume, the relative difference between the TLS and manual method was within a negligible margin of error of ±7%. Characteristics and measurements of LW in rivers can be obtained from TLS surveys, but some progress in this technique is still needed to allow a better management of the 3D point cloud and a faster extraction of the wood measurements. The proposed method represents an alternative tool for faster and repeated surveys of wood characteristics in a complex river environment, ensuring a reliable quantification of spatial and temporal variation of wood volume.

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Effects of different land-use systems (grazing and understory cultivation) on growth and yield of semi-arid oak coppices

Journal of Forestry Research ◽

10.1007/s11676-019-01063-z ◽

2019 ◽

Vol 31 (6) ◽

pp. 2235-2244

Author(s):

Ali Soltani ◽

Hamdollah Sadeghi Kaji ◽

Saleh Kahyani

Keyword(s):

Land Use ◽

Growth And Yield ◽

Site Quality ◽

Severe Drought ◽

Land Uses ◽

Zagros Mountains ◽

Wood Volume ◽

Oak Woodlands ◽

Land Use Systems ◽

Semi Arid

Abstract The present study examines the extent of negative effects of traditional multiple land-use systems on oak coppices, from a forest management point of view. The study area was located in approximately 10,000 ha of hilly Brant’s oak (Quercus brantii Lindl.) woodlands in the central Zagros Mountains. In the same site-quality class, three land-use systems were compared: simple coppice (Co), coppice in conjunction with small ruminant grazing (CoG), and coppice with understory rain-fed wheat cultivation plus grazing (CoCG). Data on total wood volume of trunk and major branches, and annual ring growth, were collected and analyzed from 74 stands in 15 coppiced woodland patches. The results showed the advantage of Co over CoG and CoCG land-uses by 43 and 60 m3 of mean accumulated wood volume per hectare, respectively. The diameter growth analysis also revealed an annual increase in wood production of trees in Co land-uses over 43 years, with an exception of the recent decade, when growth coincided with a severe drought. Using a back-extrapolation method, the minimum rotation age of woodlands in Co land-use was found to be 23.6 years, 5 and 7 years shorter than those of CoG and CoCG land-uses, respectively. Unlike CoCG, woodlands located in Co and CoG land-use systems demonstrated a high level of agreement with self-thinning rule of − 3/2. Values for the stand density index for coppiced oak woodlands were between more than 1000 for the least disturbed (Co) and less than 400 for the most disturbed woodlands (CoCG). The structure and growth rate of the coppiced oak woodlands were irreversibly disrupted by understory tillage plus grazing and in less extent by grazing alone. It was concluded that ending undergrowth cultivation in semi-arid oak coppices should be addressed as a priority by adopting minimum regulations.

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Direct and indirect drivers of instream wood in the interior Pacific Northwest, USA: decoupling climate, vegetation, disturbance, and geomorphic setting

Riparian Ecology and Conservation ◽

10.2478/remc-2014-0002 ◽

2014 ◽

Vol 2 (1) ◽

Cited By ~ 4

Author(s):

Nate Hough-Snee ◽

Alan Kasprak ◽

Brett B. Roper ◽

Christy S. Meredith

Keyword(s):

Pacific Northwest ◽

Riparian Vegetation ◽

Structural Equation ◽

Equation Model ◽

Large Wood ◽

Vegetation Composition ◽

Stream Network ◽

Wood Volume ◽

Environmental Attributes ◽

Instream Wood

AbstractInstream wood is a driver of geomorphic change in low-order streams, frequently altering morphodynamic processes. Instream wood is a frequently measured component of streams, yet it is a complex metric, responding to ecological and geomorphic forcings at a variety of scales. Here we seek to disentangle the relative importance of physical and biological processes that drive wood growth and delivery to streams across broad spatial extents. In so doing, we ask two primary questions: (1) is riparian vegetation a composite variable that captures the indirect effects of climate and disturbance on instream wood dynamics? (2) What are the direct and indirect relationships between geomorphic setting, vegetation, climate, disturbance, and instream wood dynamics? We measured riparian vegetation composition and wood frequency and volume at 720 headwater reaches within the American interior Pacific Northwest. We used ordination to identify relationships between vegetation and environmental attributes, and subsequently built a structural equation model to identify how climate and disturbance directly affect vegetation composition and how vegetation and geomorphic setting directly affect instream wood volume and frequency. We found that large wood volume and frequency are directly driven by vegetation composition and positively correlated to wildfire, elevation, stream gradient, and channel bankfull width. Indicator species at reaches with high volumes of wood were generally long-lived, conifer trees that persist for extended durations once delivered to stream habitats. Wood dynamics were also indirectly mediated by factors that shape vegetation: wildfire, precipitation, elevation, and temperature. We conclude that wood volume and frequency are driven by multiple interrelated climatic, geomorphic, and ecological variables. Vegetation composition and geomorphic setting directly mediate indirect relationships between landscape environmental processes and instream large wood. Where climate or geomorphic setting preclude tree establishment, reaches may remain naturally depauperate of instream wood unless wood is transported from elsewhere in the stream network.

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