Bank Vegetation Research Articles

Twenty years of change in riverside vegetation: what role have invasive alien plants played?

AbstractQuestionWhich environmental factors influence the occurrence of invasive alien plants (IAPs) in riparian habitats, and how much can IAPs account for change in native vegetation compared with other environmental variables?LocationRivers distributed throughout mainland Britain.MethodsWe quantified change in river bank vegetation using survey data collected approximately 20 yr apart and assessed the contribution of major IAPs (Impatiens glandulifera, Heracleum mantegazzianum and Fallopia japonica) to these changes. We also determined the importance of abiotic factors such as flow regime and land use in driving these changes.ResultsComparing data from pre‐ and post‐1990 surveys revealed that IAPs occurred mainly on lowland rivers (<200 m a.s.l.), regardless of time period, and their probability of occurrence increased over time and with rising frequency of high flows. Native plant species diversity declined over time with increasing IAP cover, along lowland rivers and along all rivers that experienced extended low flows during the growing season. These conditions particularly favoured native dominant species, whereas native subordinate species responded both positively and negatively to increased flood frequency depending on survey period. Over time, Salix spp. and larger native hydrophilic species, such as Sparganium erectum, increased along lowland rivers, replacing smaller‐statured ruderal species and driving a shift towards increased shade tolerance of subcanopy and groundcover species. Smaller compositional changes occurred in the uplands and these changes lacked a clear environmental signature.ConclusionsNational‐scale changes in native riparian vegetation are likely driven primarily by environmental changes and land‐use effects, rather than invasion by IAPs. However, IAPs, and indeed native species that benefit from abiotic changes, in turn, likely exert secondary effects on native riparian vegetation. The trend towards reduced diversity, increased shade tolerance and increased dominance of some native species and IAPs is likely linked to a set of interacting factors, including drier summers, wetter winters, increased riparian tree cover, reduced livestock access to river banks and increased fine sediment input. Determining combined effects of land use, IAPs and climate‐related changes in flow regime over decadal time scales (i.e. ~20 yr) is important for predicting ecological responses of vulnerable habitats under future disturbance scenarios.

Sandhill crane roost selection, human disturbance, and forage resources

ABSTRACTSites used for roosting represent a key habitat requirement for many species of birds because availability and quality of roost sites can influence individual fitness. Birds select roost sites based on numerous factors, requirements, and motivations, and selection of roosts can be dynamic in time and space because of various ecological and environmental influences. For sandhill cranes (Antigone canadensis) at their main spring‐staging area along the Platte River in south‐central Nebraska, USA, past investigations of roosting cranes focused on physical channel characteristics related to perceived security as motivating roost distribution. We used 6,310 roost sites selected by 313 sandhill cranes over 5 spring migration seasons (2003–2007) to quantify resource selection functions of roost sites on the central Platte River using a discrete choice analysis. Sandhill cranes generally showed stronger selection for wider channels with shorter bank vegetation situated farther from potential human disturbance features such as roads, bridges, and dwellings. Furthermore, selection for roost sites with preferable physical characteristics (wide channels with short bank vegetation) was more resilient to nearby disturbance features than more narrow channels with taller bank vegetation. The amount of cornfields surrounding sandhill crane roost sites positively influenced relative probability of use but only for more narrow channels <100 m and those with shorter bank vegetation. We confirmed key resource features that sandhill cranes selected at river channels along the Platte River, and after incorporating spatial variation due to human disturbance, our understanding of roost site selection was more robust, providing insights on how disturbance may interact with physical habitat features. Managers can use information on roost‐site selection when developing plans to increase probability of crane use at existing roost sites and to identify new areas for potential use if existing sites become limited. © 2016 The Wildlife Society.

Comparisons of Canyon Grassland Vegetation and Seed Banks along an Early Successional Gradient

Abstract The seed bank represents the future trajectory of plant communities following disturbance and is vital to their regeneration. Worldwide, grassland seed banks have been well studied. However, there are no examinations of the seed bank for the Pacific Northwest Bunchgrass Prairie system found in the Pacific Northwest of the United States. This absence may arise from the limited amount of intact grasslands in this type following decades of agricultural development and cultivation. In this study, we examined the seed bank from grasslands sites along an early successional gradient to evaluate how they relate to above ground vegetation, successional stage, and historical cultivation. We found that similarities between above ground vegetation and the seed bank were the strongest in the earliest successional stages, when annual grasses dominate. Surprisingly, this relationship was driven by the presence of a relatively new introduced annual grass, Ventenata dubia. Finally, the seed bank within cultivated...

Evaluation of the two model biocorridors in South-West part of Slovakia in agricultural landscape

Evaluation of the two model biocorridors in South-West part of Slovakia in agricultural landscape

Molecular analysis of the extinct Central European endemic Saxifraga oppositifolia subsp. amphibia and its implications on glaciation biogeography

Extinction of biodiversity due to human activities is a severe global problem. In Europe, however, only a few plant species died out so far. We investigated a dubious, disregarded taxon—Saxifraga oppositifolia subsp. amphibia—which became extinct in the 1960s. It exclusively occurred in a specific niche, namely in seasonally flooded waterside bank vegetation around Lake Constance in Germany and Switzerland. It has either been interpreted as a glacial relict or as a recent dealpine taxon. Using herbarium material, we conducted phylogenetic analyses based on ITS and cpDNA sequence variation. The taxon shared a chloroplast haplotype of S. oppositifolia, which is mainly distributed in the Alps, favouring the dealpine hypothesis. Nuclear data revealed several paralogous copies nested inside S. oppositifolia, most of which, however, differed from other S. oppositifolia accessions including those from the vicinity of Lake Constance. The oldest mean stem node ages of these ITS copies date between 0.91 and 0.28 my. Contradicting cpDNA, this may indicate that this saxifrage was a distinct taxon and possibly a relict originating in Middle Pleistocene glaciations. If so, the present study exemplifies that arctic-alpine plants survived in specific niches at low altitudes during interglacials and that corresponding taxa with a limited distribution are especially prone to extinction.

Micro and Macroscale Drivers of Nutrient Concentrations in Urban Streams in South, Central and North America.

Global metrics of land cover and land use provide a fundamental basis to examine the spatial variability of human-induced impacts on freshwater ecosystems. However, microscale processes and site specific conditions related to bank vegetation, pollution sources, adjacent land use and water uses can have important influences on ecosystem conditions, in particular in smaller tributary rivers. Compared to larger order rivers, these low-order streams and rivers are more numerous, yet often under-monitored. The present study explored the relationship of nutrient concentrations in 150 streams in 57 hydrological basins in South, Central and North America (Buenos Aires, Curitiba, São Paulo, Rio de Janeiro, Mexico City and Vancouver) with macroscale information available from global datasets and microscale data acquired by trained citizen scientists. Average sub-basin phosphate (P-PO4) concentrations were found to be well correlated with sub-basin attributes on both macro and microscales, while the relationships between sub-basin attributes and nitrate (N-NO3) concentrations were limited. A phosphate threshold for eutrophic conditions (>0.1 mg L-1 P-PO4) was exceeded in basins where microscale point source discharge points (eg. residential, industrial, urban/road) were identified in more than 86% of stream reaches monitored by citizen scientists. The presence of bankside vegetation covaried (rho = –0.53) with lower phosphate concentrations in the ecosystems studied. Macroscale information on nutrient loading allowed for a strong separation between basins with and without eutrophic conditions. Most importantly, the combination of macroscale and microscale information acquired increased our ability to explain sub-basin variability of P-PO4 concentrations. The identification of microscale point sources and bank vegetation conditions by citizen scientists provided important information that local authorities could use to improve their management of lower order river ecosystems.

Ecologia e história natural de Hypsiboas curupi (Anura, Hylidae): um anfíbio endêmico do sul da Mata Atlântica

Data on habitat use and life history are essential for evaluation of the conservation status of species, and may direct policy for preservation of natural environments. Over the course of a year, we investigated populations of Hypsiboas curupi regarding (i) nighttime activity patterns; (ii) associations with climatic variables; (iii) the spatial distribution patterns of males and females with respect to microhabitat use; and (iv) variation in body size. The study was carried out from August 2010 to July 2011 in the Parque Estadual Fritz Plaumann, a seasonal deciduous forest fragment in the western region of Santa Catarina, southern Brazil. Calling activity was highest from August to November. The number of calling males was highest at 23h, and the frequency of occurrence was influenced by the air humidity. Calling males, non-calling males, and females differed in their distance from the bank and substrate type used. Females were significantly larger and heavier than males. Our results indicate that H. curupi is highly dependent on bank vegetation, and that changes in riparian vegetation structure due to human activity can result in the loss of sites for calling and oviposition, and may reduce availability of food and shelter. Keywords: life history, riparian forest, stream-dwelling amphibians, seasonal deciduous forest, microhabitat use.

The use of line transects for an accurate description of river bank vegetation

The last decades, considerable efforts have been made to increase the habitat diversity of river banks along navigable waterways. In particular the construction of nature friendly bank protections aimed to preserve or restore ecological gradients, enhancing habitat diversity. To evaluate the ecological gain obtained so far, monitoring studies are performed. The use of the quadrat method is widespread in the vegetation monitoring of river banks. However, when monitoring narrow river banks, this method has serious restrictions. A possible alternative could be the use of a line transect method. Both methods were compared by calculating weighted averages of Ellenberg indicator values of all species present in a sample area, to determine the most appropriate method. We observed that the Ellenberg indicator value for moisture was the most appropriate variable to describe changes perpendicular to the waterline. When comparing both methods through time, they seemed to produce similar results in the case of species poor vegetation types such as reedbeds or some grassland types. Nevertheless the line transect method produced a much better description of the spatial gradient complexity. The use of the most efficient monitoring method is determinant to accurately evaluate the present gradients and the gradients after an intervention has taken place.

The role of life history traits and habitat characteristics in the colonisation of a secondary floodplain by neobiota and indigenous macroinvertebrate species

Modification of streams and rivers has mediated range expansions of several species into areas beyond their natural distribution. In this study, a newly created secondary floodplain channel (SFC), with three connections to the Danube, was used as a model system to compare colonisation by indigenous versus non-indigenous species of macroinvertebrates. Three years after the opening of the channel, it was colonised by 210 taxa. Indigenous species were more abundant than non-indigenous ones, both in the channel as well as in the Danube, and colonisation was mostly determined by habitat characteristics. In non-indigenous species, proximity to the source habitat was the main explanatory variable. Non-indigenous colonisers mostly had indifferent functional traits, in contrast to indigenous macroinvertebrates. These differences were particularly pronounced in amphipods where an equal number of five species per group occurred. The results of this study suggest that the factors determining colonisation patterns of indigenous versus non-indigenous species with similar dispersal abilities can strongly differ. Consequently, the creation of specific habitat structures (gravel-dominated, high current flow, bank vegetation) in restoration of floodplain channels can increase competitiveness of native species valued in conservation, particularly if sufficiently long channels with limited edge effects to the source habitat are built.

Is the Sosiani River Healthy? Investigating the Relationship between Water Quality Indicators and Macroinvertebrate Assemblages in the Sosiani River

The health of rivers is of great concern to governments and communities worldwide due to their important ecological functions. Numerous studies have established that water quality indicators have a positive effect on river health. However, only a few studies have examined equatorial rivers, and, to date, there has been no study on the Sosiani River in Kenya. As such, this study explored the health of the Sosiani River by considering how its aquatic macroinvertebrate assemblages were affected by various water quality parameters. The research considered whether there was a relationship between water quality indicators and macroinvertebrate assemblages in the Sosiani River. This knowledge is of paramount importance to the communities and decision makers of the Sosiani catchment, and Kenya as a whole, since there is need to understand the relationship between the water quality indicators and the health of the river in order to allocate resources for its rehabilitation and maintenance. This study examined 10 sites, nine being “test” sites and one a “reference” site. The study established a significant relationship between water quality parameters and macroinvertebrate assemblages. The sites with natural riparian zone vegetation conditions were found to have more Ephemeroptera, Plecoptera, and Trichoptera macroinvertebrates when compared to those without or with exotic vegetation. In terms of absolute numbers of surface aquatic macroinvertebrates, sites characterised by dense stream bank vegetation had more macroinvertebrates than those characterised by forest with eroded, bare stream banks. From the study, it was therefore concluded that Sosiani River is healthier at head waters where there was natural forests compared to downstream where there was plantations, intensive farming and urban area. The study recommends that more detailed studies classify macroinvertebrates to gunus level and include microinvertebrates, since this may give a more accurate assessment of the river’s health. The study further recommends that identification keys for East African macroinvertebrates be developed.

Diet composition of the Eurasian otter Lutra lutra in different freshwater habitats of temperate Europe: a review and meta‐analysis

Abstract The Eurasian otter Lutra lutra is a top predator that feeds mostly on fish. Yet, studies show the high plasticity of otter foraging behaviour and the varying importance of alternative food types in the species' diet. The aims of this study were, firstly, to demonstrate by meta‐analysis how the diet composition of otters varies depending on the habitat occupied, in terms of the types of land use, waterbody, and bank vegetation. Secondly, we tested whether the choice of method of presenting prey percentages in the diet of otters influenced the conclusions of the meta‐analysis. The percentage of fish in the diet was greater for otters occupying standing water than for those occupying flowing water; was higher for otters in waterbodies overgrown by reed vegetation; and varied depending on the type of surrounding land use. However, the results of the meta‐analysis varied depending on which of the two most common methods of diet analysis were used: percentage biomass or relative frequency of occurrence (RFO). We showed that the plasticity of otter feeding behaviour might be explained by the various habitats occupied by otters. Habitat differences reflected in otters' diets might have importance for the maintenance and conservation of local populations of this species. The high diversity of methods used by researchers to report the results of dietary studies precludes full comparisons and synthesis. This demonstrates the importance of unification of reporting. Moreover, the conclusions reached by the authors of any particular study might be highly dependent on the method they applied. Thus, care should be taken when comparing ecological studies based on different methods.

Territorial Systems of Ecological Stability in Land Consolidation Projects (Example of Proposal for the LSES of Klasov Village, Slovak Republic)

Abstract The observation of spatial and functional relations within ecosystems (Forman, Godron, 1993; Michal, 1994; Jongman, 1995 a,b) and Territorial Systems of Ecological Stability and their design have a successful history not only in the Czech Republic, Germany, Austria, Hungary but also in Slovakia and other countries. The main principle of their design is to create an ecological network in intensively utilised landscape through revitalisation of the existing natural habitats and creation of new ones along with the proposal of their protection and management. The presented contribution represents an example of the proposed spatial framework of ecological stability and management measures in the cadastral area of Klasov. The cadastral area is characterised by prevailing large-block arable parcels and viticultural history. In spite of the agricultural character of the landscape, there are also areas with dispersed non-forest woody vegetation, preserved bank vegetation along streams, wetlands with reed associations, forest growths and mosaics of old abandoned orchards and vineyards as the potential elements of the proposed spatial framework of ecological stability. A functional LTSES framework and implementation of the system of ecostabilizing measures may contribute to increasing diversity of the territory and improvement of its spatial ecological stability. Efforts aimed at the recovery of vine-growing tradition represent a positive feature in terms of increased diversity in the territory.

Potential of soil seed banks in the ecological restoration of overgrazed floor vegetation in a cool-temperate old-growth damp forest in eastern Japan

Damp forests are vulnerable ecosystems and have peculiar species compositions. Deer can cause severe damage to damp forest composition and structure. However, little is known about the effect of deer on soil seed banks of damp forests and the restoration potential of soil seed banks. I surveyed the compositions of the soil seed bank and floor vegetation both inside and outside a deer exclosure in an old-growth damp forest in eastern Japan using the seedling emergence method. Floor vegetation was composed of 71 % palatable and 1 % unpalatable species inside the exclosure but 6 % palatable and 83 % unpalatable species outside the exclosure. Forty-four species and 642 seeds m−2 germinated inside the exclosure, whereas 39 species and 985 seeds m−2 germinated outside the exclosure. Seed bank composition was 29 % palatable and 43 % unpalatable species inside the exclosure and 1 % palatable and 73 % unpalatable species outside the exclosure. Percentage similarity between the soil seed bank outside and the floor vegetation inside the exclosure was very low. These results indicate that the soil seed bank outside the exclosure has little potential to aid the recovery of floor vegetation. Conservation measures, such as deer exclosures and deer control, must be introduced before the floor vegetation is retrogressed by sika deer grazing.

Resource Partitioning and Niche Overlap in Three Sympatric Species of Dragonflies (Anisoptera Libellulidae) in Anuradhapura District, Sri Lanka

Resource partitioning in ecological communities bears profound connection with the coexistence of closely related species. As a mechanism, it assists species with similar characteristics to thrive in the environments where they can utilise resources in different levels in spatial and temporal scale via niche partitioning. As ecologically important insects, dragonflies are well-studied in many aspects globally but poorly assessed locally. The current study was conducted under the main objective of identifying the mechanism of resource partitioning in three sympatric most common skimmer species; Brachythemis contaminata , Crocothemis servilia servilia and Rhyothemis variegata variegata in two tank ecosystems in Anuradhapura district, Sri Lanka. The study was conducted from May-August 2014 simultaneously in Nabadagaswewa tank (NW) and Mihintale tank (MT). Data collection was carried out 08:00 to 10:00 hrs in the morning and 13:00 to 15:00 hrs in the evening. Land-water interface at the tank was used for the study in both sites. Scan sampling was used to obtain data on resource utilisation by the three skimmer species. Randomly selected individuals were observed for 30 seconds in each observation point. Vegetation variables (bank vegetation density and height, aquatic vegetation density and height) were measured using two belt transects (25×1 m2) in both habitats. The three species were more active in the morning hours (08:00 to 10:00 hrs) and shows different levels of perch and fly heights in the morning and evening hours. R.v. variegata was recorded using heights of <100 cm in both habitats. B. contaminata and C.s. servilia showed high spatial niche overlap (Oij=0.716) in NW and in MT highest spatial niche overlap was observed between C.s. servilia and R.v. variegata (Oij=0.473). The broadest niche breadth was exhibited by C.s. servilia (B=0.46) in NW while B. contaminata showed the highest (B=0.23) in MT. R.v. variegata showed the lowest niche breadth in both habitats (NW: B = 0.39, MT: B=0.09). Relationship between the species abundance and vegetation heights and densities shows that vegetation height and bank vegetation densities were negatively correlated with the abundance of the three skimmer species. This study depicts ways of resource partitioning among the three sympatric skimmer species minimising interspecific competition and favoring their co-existence. Further, it highlights the extent of spatial niche overlap is influenced by the habitat characteristics especially the vegetation structure and resource availability. Keywords: Resource partitioning, Niche overlap, Libellulidae

Habitat and water quality as drivers of ecological system health in Central Appalachia

Ecological mitigation in Central Appalachia often takes one of two approaches: a water quality-driven focus (TMDLs), or a geomorphological focus on stream/habitat restoration (404 permit-related requirements). While often successful at reducing in-stream pollutants or restoring stable hydrology respectively, recent studies have shown that neither approach appreciably improves aquatic ecosystem health. We report here on a field sampling campaign along the Kentucky–Virginia border aimed at identifying primary macroinvertebrate stressors in order to inform ecological remediation efforts and how those efforts might fit into the current regulatory structure. Over two years, we collected 178 observations of benthic species diversity at 36 unique sites representing watersheds of varying surface disturbance and anthropogenic activities, along with associated data from rapid bioassessment protocols (RBPs). Using land use metrics (derived from GIS data), water quality data, habitat metrics, and stream condition indices, principal component analysis (PCA) identified surface disturbance, forest cover, and specific conductivity as significant variables comprising the first PC. Habitat appears to be a secondary driver affecting community sensitivity with channel alteration, bank vegetation, riparian vegetation, and epifaunal substrate contributing significantly to the second PC. PERMANOVA analysis showed these groups to be significantly different from one another (p=0.001), R2=0.44. Change point analysis via 500 bootstrapped replications identified shifts in community composition means at 326, 609, and 1065mS/cm along the conductivity gradient, and habitat change points at 42.6 and 58.2 along the composite habitat gradient. These findings suggest that approaches that improve water quality, upland hydrology, and localized habitat structures may simultaneously be necessary to improve aquatic ecosystem health.

Detection probabilities and sampling rates for Anisoptera exuviae along river banks: influences of bank vegetation type, prior precipitation, and exuviae size

Exuviae collections have considerable value in population studies of Odonata, but methods for standardizing collections or estimating densities and detection probabilities have been little studied. I measured sampling rates for Anisoptera exuviae and used a maximum likelihood, four-pass, depletion population estimator to standardize collections and to estimate exuvial densities and detection probabilities along 10 riverbank stations in Wisconsin. First-pass sampling rates averaged slower than the overall average for experienced collectors (0.53 m min–1 compared to 0.90 m min–1) because more exuviae were present on the first pass, increasing picking and handling time. Neither bank vegetation type (grassy versus forested) nor amount of prior precipitation affected sampling rate. Exuviae detection probabilities for a single pass ranged from 0.49 to 0.75, and averaged 0.64. The mean cumulative probability of detection increased to 0.87 after two passes, 0.95 after three passes, and 0.98 after four passes. A s...

Hydropeaking induces losses from a river reach: observations at multiple spatial scales

AbstractIn humid regions, where gaining river conditions generally prevail, daily hydroelectric dam releases alter downstream surface water–groundwater interactions by reversing the head gradient between river and adjacent groundwater. Previously, it has been noted that artificial stage changes due to dam releases enhance hyporheic exchange. Here we investigate the regulated Deerfield River in northwestern Massachusetts at multiple scales to evaluate how changing downstream geologic conditions along the river mediate this artificial hyporheic pumping.Water budget analysis indicates that roughly 10% of bank‐stored water is permanently lost from the 19.5‐km river reach, likely as a result of transpiration by bank vegetation. An adjacent reference stream with similar dimensions and geomorphology, but without hydropeaking, shows predictable gaining conditions. Field observations from streambed piezometers and thermistors show that water losses are not uniform throughout the study reach. Riparian aquifer transmissivity in river sub‐reaches largely determines the magnitude of surface water–groundwater exchange as well as net water loss from the river. These newly documented losses from hydropeaking river systems should inform decisions by river managers and hydroelectric operators of additional tradeoffs of oscillatory dam‐release river management. Copyright © 2015 John Wiley &amp; Sons, Ltd.

High frequency and counterstroking:Calopteryx splendensfemale threatening flight

A hitherto unknown flight pattern of female Calopteryx splendens is described. On a day with heavy winds, when no damselfly could fly in open space of the river, I observed and filmed four to six females foraging in a small bay sheltered by bank vegetation. Females fought for perches and showed a threatening flight with counterstroking and high frequency wing-beating. In all other female flight modes the fore and hind wings were beaten nearly in parallel with a much lower beat frequency. As the newly observed flight mode resembles the courting flight mode of males of C. splendens the female's threatening flight is compared with it. At landings of both sexes the wings were beaten in a counterstroking mode for one to seven beats, as well. The possible development of female's threatening flight from wing beating during landing of C. splendens is discussed. The relevance of these findings is to extend the knowledge about the variety of flight modes in Calopteryx females.

An agricultural drainage channel classification system for phosphorus management

In agricultural landscapes, surface ditches and streams can significantly influence the attenuation and transfer of phosphorus (P) from upstream sources to receiving water-bodies. The magnitude of P attenuation and/or transfer within channels can vary considerably according to fine sediment retention and/or transfer processes. Fine sediment retention and/or transfer processes can, in turn, vary considerably according to channel physical characteristics. An understanding of channel physical characteristics, their effect on fine sediment retention/transfer and their spatial distribution, could be used to develop channel-specific management strategies for the reduction of downstream P transfers. Using a detailed field survey of surface channel networks in a well-drained arable and a poorly-drained grassland catchment, this study (i) characterised the surface channels in both catchments, (ii) classified the channels into four classes of fine sediment retention and/or transfer likelihood based on a comparison of physical characteristics (slope and drainage area) with observations of fine sediment accumulation and (iii) considered P management strategies that are suited to each class. Results of the survey demonstrated that ditch dimensions were not closely related to their indicative flow volumes and were over-engineered, which likely reduces downstream P transfer. Net attenuation of fine sediment and associated P was predicted for 40% of the total channel length in the grassland catchment, compared to 13% of the total channel length in the arable catchment. Net transfer of fine sediment and associated P was predicted for 24% of the total channel length in the grassland catchment compared to 58% of the total channel length in the arable catchment. For eutrophication management in headwaters, periodic removal of fine sediment and maintenance of channel bank vegetation in net attenuating and transferring channels respectively would help to minimise P transfers from these catchments.

Flow and force-balance relations in a natural channel with bank vegetation

ABSTRACTThe typical flow dynamics of meandering streams related to curvature and associated bed topography can be altered by stream width variations and vegetation. This paper presents laboratory experiments conducted in a reduced-scale model of a low-sinuosity, variable-width bend with and without vegetation on the outer bank. Measurements of velocities and water surface elevations on a dense grid allowed, for the first time, the quantification of fluxes and forces that influence flow structure. Experiments without vegetation showed superelevation of water surface along the outer bank due to centrifugal effects, accompanied by longitudinal variations in water-surface gradients associated with width changes, as the channel was narrower near the bend inflection and wider near the apex. High outer bank velocities developed in the downstream part of the bend due to the absence of well-developed bed topography. Vegetation reduced centrifugal effects at the bend entrance but enhanced them at the bend exit, affecting flow in the downstream bend.