Predicting Long‐Term Changes in Riparian Bird Communities in Floodplain Landscapes

As anthropogenic impacts on riverine ecosystems expand, both aquatic and terrestrial ecosystems are influenced over large spatiotemporal scales. We predicted how riparian bird communities changed in response to long‐term changes in floodplain landscapes such as woodland expansion (i.e. rapid increases in vegetation cover on gravel bars and the progress of vegetation succession due to a decrease in the frequency and magnitude of flood disturbance). To test the hypothesis that woodland expansion after dam construction reduces the abundance of gravel bar‐nesting birds and increases the abundance of forest‐nesting birds, we estimated historical changes between past and present bird abundances using species distribution models across multiple rivers that were either unregulated or regulated by dams. We created past and present vegetation maps from remote sensing images and used habitat quantities as explanatory variables in the species distribution models. As we hypothesized, the estimated abundance of gravel bar‐nesting birds decreased and that of forest‐nesting birds increased because of woodland expansion in some regulated rivers. This suggests that anthropogenic alterations of riverine conditions (e.g. dam construction) can affect terrestrial ecosystems (e.g. riparian bird communities) through changes in floodplains (e.g. woodland expansion). In addition, our findings highlight the efficacy of combining spatial and temporal analyses when examining long‐term ecological dynamics. Copyright © 2013 John Wiley & Sons, Ltd.     

Regional differences in nutrient limitation in floodplains of selected European rivers: implications for rehabilitation of characteristic floodplain vegetation

Extremely high river discharges in 1993 and 1995 along the Dutch rivers Rhine and Meuse have increased the public awareness of possible safety threats. As a result the ‘Space for Rivers’ program was implemented, aiming at restoring physical space for the rivers in combination with ecological rehabilitation. However, the development of species‐rich vegetation types in these floodplain areas is lagging behind restoration targets and biogeochemical constraints may play a vital role in this. Biogeochemical, hydrological and vegetation data were collected in 111 plots in both rehabilitated and original floodplains in regulated and more pristine river systems in The Netherlands and Poland. Soil nutrient and soil pore water data were summarized by factor analysis and the subsequent principal components were compared to vegetation and hydrological data by correlation analysis. The correlation analyses between vegetation parameters including nutrient stoichiometry and the biogeochemical soil variables resulted in a remarkable difference between pristine and impacted river systems. The results suggest a clear N‐limitation of plant growth in pristine floodplains, and apparent absence of limitation in regulated, impacted floodplains. In addition, results indicate that flooding events do not lead to one‐way transport of sediment and nutrients from the river into the floodplains; rather they indicate that highly dynamic hydrological conditions prevent soils from accumulating organic matter and nutrients. This study shows that nutrient limitation in regulated floodplains shifted from distinctly N‐limited plant growth to no nutrient limitation at all, probably due to decades of high fertilizer and manure application and nutrient input by the rivers during flooding. The consequence of our findings for rehabilitation activities is that it might be necessary to restore nitrogen limitation in floodplain systems in order to create opportunities for a species‐rich floodplain vegetation, through nutrient removal by hay‐making. Copyright © 2006 John Wiley & Sons, Ltd.     

VEGETATION–LANDFORM ASSEMBLAGES ALONG SELECTED RIVERS IN THE CZECH REPUBLIC,A DECADE AFTER A 500‐YEAR FLOOD EVENT

Rivers with a natural flow regime strongly influence the dynamics of riparian plant communities through hydrological and geomorphological processes. In this study, associations between fluvial landforms and vegetation are investigated on three near‐natural rivers in the Czech Republic a decade after a 500‐year return period flood in July 1997. This extreme disturbance destroyed the anthropogenically modified river channels and created suitable conditions for a range of ecosystems with high diversity and ecological stability. Field surveys were conducted on fluvial landforms (bars, islands, banks, floodplains and terraces) along three ‘renaturalized’ rivers, where no technical modifications had subsequently been made to their channels outside urban areas and the floodplains had been left in a post‐flood state. Vegetation species abundance and 13 environmental variables (topographical, hydrological and soil) were investigated in summer 2007, 10 years after the extreme flood disturbance. The results suggest that the recently created fluvial geomorphic forms are key environmental determinants of riparian vegetation distribution patterns. A range of statistical analyses illustrate that some plant species show predictable patterns of occurrence that correspond with the fluvial forms, supporting a fourfold grouping of herbaceous and woody species and the identification of typical plant communities associated with gravel bars, islands, banks, floodplains and terraces. An investigation of the species richness found on different fluvial landforms showed that the highest number of species occurred on the floodplain and decreased gradually towards the channel bed and towards terraces. Investigation of existing conditions in reaches of rivers with natural dynamics of fluvial processes provides valuable information that can be used as an effective tool for planning restoration strategies and precise management. However, the most important finding of this study is the remarkable establishment of complex river corridor vegetation–landform associations within 10 years of a 500‐year flood that removed the heavily cultivated landscape that had existed before the event. Copyright © 2011 John Wiley & Sons, Ltd.     

RESERVOIR FLOODPLAINS SUPPORT DISTINCT FISH ASSEMBLAGES

Reservoirs constructed on floodplain rivers are unique because the upper reaches of the impoundment may include extensive floodplain environments. Moreover, reservoirs that experience large periodic water level fluctuations as part of their operational objectives seasonally inundate and dewater floodplains in their upper reaches, partly mimicking natural inundations of river floodplains. In four flood control reservoirs in Mississippi, USA, we explored the dynamics of connectivity between reservoirs and adjacent floodplains and the characteristics of fish assemblages that develop in reservoir floodplains relative to those that develop in reservoir bays. Although fish species richness in floodplains and bays were similar, species composition differed. Floodplains emphasized fish species largely associated with backwater shallow environments, often resistant to harsh environmental conditions. Conversely, dominant species in bays represented mainly generalists that benefit from the continuous connectivity between the bay and the main reservoir. Floodplains in the study reservoirs provided desirable vegetated habitats at lower water level elevations, earlier in the year, and more frequently than in bays. Inundating dense vegetation in bays requires raising reservoir water levels above the levels required to reach floodplains. Therefore, aside from promoting distinct fish assemblages within reservoirs and helping promote diversity in regulated rivers, reservoir floodplains are valued because they can provide suitable vegetated habitats for fish species at elevations below the normal pool, precluding the need to annually flood upland vegetation that would inevitably be impaired by regular flooding. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

Associations between riparian plant morphological guilds and fluvial sediment dynamics along the regulated Colorado River in Grand Canyon

Effects of riparian vegetation on fluvial sediment dynamics depend on morphological traits of the constituent species. Determining the effects of different morphological guilds on sedimentation rates, as influenced by multiple aspects of dam operations, can help identify viable strategies for streamflow and vegetation management to achieve riparian resource goals. Plants of increasing size and branching density or complexity have been found to have greater effects on sedimentation in free‐flowing systems; however, this relationship could differ in regulated rivers. We tested the hypothesis that plant guilds of increasing height and branching complexity would be positively associated with sedimentation rates on 23 sandbars deposited in zones of recirculating flow (eddies) along the Colorado River in Grand Canyon. We used an image‐based vegetation classification and digital elevation models from annual topographic surveys to track associations between six plant morphological guilds and topographic change over 5 years. Vegetation had significant associations with deposition after accounting for geomorphic setting, but the ordinal guild scale was not positively correlated with deposition magnitude. Instead, low‐statured rhizomatous and herbaceous guilds were particularly effective at capturing sediment in the separation zone of sandbars, whereas tall herbs and large shrubs were most effective at capturing sediment in reattachment zones. These nuanced interactions between geomorphic position and morphological guild may be a direct consequence of flow regulation through modifications to physical deposition and erosion processes. Flow regulation may also select for a narrow subset of morphological guilds, reducing the diversity of vegetation feedbacks on sedimentation and emphasizing geomorphic drivers.     

Management of vegetation encroachment by natural and induced channel avulsions: A physical model

Flow regulation and water abstractions may change the complex relationship between river hydraulics, morphology, and riparian vegetation. As a result, rivers are likely to decrease their dynamics, increase the amount of vegetation, and modify their habitat structure. Flood events provide a natural mechanism for removal of invasive vegetation and recreation of natural floodplain habitats. This work aims at evaluating and quantifying how gravel‐bed braided rivers naturally control vegetation encroachment through morphological processes and the impact of both naturally occurring and induced avulsions. Flume experiments were conducted in a 24‐m‐long x 1.6‐m‐wide channel filled with well‐sorted sand and constant longitudinal gradient at 0.01 m/m. Once a braided network developed, the flume was seeded with Eruca sativa at a density of 1.5 seeds/cm² and grown until an approximate height of 1.1 cm. Experiments evaluated low‐, medium‐, and large‐flood events and documented morphological changes and impacts to vegetation at four intervals during the experiments. High‐resolution images captured approximately 3 m above the flume were used to produce accurate Structure‐from‐Motion‐derived topography and orthoimagery (average errors 2 mm). Vegetation dynamics were observed to be highly variable and depend on local morphological changes and bank erosion. Discharge is the first‐order control on vegetation removal, but our results show that occurrence of avulsions significantly increases vegetation removal. The experiments highlight that a relatively small amount of sediment relocation can be an effective tool to induce avulsions and reduce vegetation encroachment on regulated rivers.     

Quantifying the effect of riparian forest versus agricultural vegetation on river meander migration rates,central Sacramento River,California, USA

Riparian forest vegetation is widely believed to protect riverbanks from erosion, but few studies have quantified the effect of riparian vegetation removal on rates of river channel migration. Measured historical changes in a river channel centreline, combined with mapped changes in floodplain vegetation, provide an opportunity to test how riparian vegetation cover affects the erodibility of riverbanks. We analysed meander migration patterns from 1896 to 1997 for the central reach of the Sacramento River between Red Bluff and Colusa, using channel planform and vegetation cover data compiled from maps and aerial photography. We used a numerical model of meander migration to back‐calculate local values for bank erodibility (i.e. the susceptibility of bank materials to erosion via lateral channel migration, normalized for variations in near‐bank flow velocities due to channel curvature). A comparison of migration rates for approximately 50 years before and after the construction of Shasta dam suggests that bank migration rates and erodibility increased roughly 50%, despite significant flow regulation, as riparian floodplains were progressively converted to agriculture. A comparison of migration rates and bank erodibilities between 1949 and 1997, for reaches bordered by riparian forest versus agriculture, shows that agricultural floodplains are 80 to 150% more erodible than riparian forest floodplains. An improved understanding of the effect of floodplain vegetation on river channel migration will aid efforts to predict future patterns of meander migration for different river management and restoration scenarios. Copyright © 2004 John Wiley & Sons, Ltd.     

Mesoscale river restoration enhances the diversity of floodplain vegetation

Effective river restoration aims for the recovery of ecosystem functions by restoring processes and connectivity to the floodplain. At the straightened lowland river Stör in northern Germany, a sequence of 15 new meanders was created in 2008, with wavelengths up to 70 m. The newly created areas within the meander bends range in size from 215 to 1,115 m² and function as a series of 15 restored floodplain sites, which are subject to succession. After 7 years of restoration measures, we investigated the vegetation dynamics on the (a) restored floodplains and compared them with adjacent floodplain sites that were used as (b) low‐intensity grazed grassland or as (c) abandoned grassland. We analysed the species diversity, functional vegetation parameters, and plant communities of 200 plots within the floodplain area of the three floodplain types and of 246 plots at their river banks. Plant species diversity and composition differed with respect to restoration measure and site management. Restored floodplains revealed a higher coverage in species of wet grasslands and softwood forests and higher species diversity than abandoned grasslands. Grazed grasslands showed the highest species number and coverages of pioneer vegetation. The banks indicated fewer differences in species composition between floodplain types. The construction of restored floodplains revealed greater overall plant diversity due to promoting the development of typical floodplain vegetation. Shallow meanders with increased flooding intensity and the creation of a varying microreliefs are recommended as combined river/floodplain measures in order to foster processes and connectivity between valley components.     

Novel plant communities limit the effects of a managed flood to restore riparian forests along a large regulated river

Dam releases used to create downstream flows that mimic historic floods in timing, peak magnitude and recession rate are touted as key tools for restoring riparian vegetation on large regulated rivers. We analysed a flood on the 5th‐order Green River below Flaming Gorge Dam, Colorado, in a broad alluvial valley where Fremont cottonwood riparian forests have senesced and little recruitment has occurred since dam completion in 1962. The stable post dam flow regime triggered the development of novel riparian communities with dense herbaceous plant cover. We monitored cottonwood recruitment on landforms inundated by a managed flood equal in magnitude and timing to the average pre‐dam flood. To understand the potential for using managed floods as a riparian restoration tool, we implemented a controlled and replicated experiment to test the effects of artificially modified ground layer vegetation on cottonwood seedling establishment. Treatments to remove herbaceous vegetation and create bare ground included herbicide application (H), ploughing (P), and herbicide plus ploughing (H + P). Treatment improved seedling establishment. Initial seedling densities on treated areas were as much as 1200% higher than on neighbouring control (C) areas, but varied over three orders of magnitude among the five locations where manipulations were replicated. Only two replicates showed the expected seedling density rank of (H + P) > P > H> C. Few seedlings established in control plots and none survived 1 year. Seedling density was strongly affected by seed rain density. Herbivory affected growth and survivorship of recruits, and few survived nine growing seasons. Our results suggest that the novel plant communities are ecologically and geomorphically resistant to change. Managed flooding alone, using flows equal to the pre‐dam mean annual peak flood, is an ineffective riparian restoration tool where such ecosystem states are present and floods cannot create new habitat for seedling establishment. This problem significantly limits long‐term river and riparian management options. Copyright © 2010 John Wiley & Sons, Ltd.     

MORPHOLOGICALLY RELATED INTEGRATIVE MANAGEMENT CONCEPT FOR RECONNECTING ABANDONED CHANNELS BASED ON AIRBORNE LiDAR DATA AND HABITAT MODELLING

Most of the large rivers are heavily degraded and lack near‐natural conditions due to high human pressure (agricultural use and settlements) especially on former inundation areas. Hence, it is rarely possible to ‘restore’ predisturbance conditions of rivers and their floodplains. Further, river or floodplain restoration programs are often based on type‐specific reference conditions. Those reference conditions are mainly determined on the basis of historical maps not giving any information of, for example, sediment supply, flood frequency and vegetation cover (density). Especially for improving the ecological status of rivers with abandoned channel features, key habitats for target fish species have to be restored by reconnecting floodplains and their secondary channel system. In addition, because of the necessity of improving the ecological status, there is growing interest in interdisciplinary river restoration techniques. Within the presented article, an integrative concept is derived based on Light Detection and Ranging measurements and numerical modelling with respect to river dynamics (hydrologic and morphological). Further habitat modelling, based on unsteady depth‐averaged two‐dimensional hydrodynamics, is applied with a focus on the mesounit scale. For testing the conceptual model, various river reaches at the Morava River were selected, featuring different morphological characteristics. It was found that the applied management concept allows considering the important issues of river dynamics (morphological/hydrologic) using a flow‐ and flood‐pulse approach for identifying bottlenecks of target species at the Morava River. The reconnection of abandoned channels will result in an increase of hydromorphological heterogeneity and/or woody debris within the study reach. This might be of high relevance for habitat features (e.g. backwater habitats) especially for flow pulses between low flow and mean flow and/or in reaches without abandoned channels between low‐flow and the bankfull stage. Copyright © 2012 John Wiley & Sons, Ltd.     

Dynamics of river fish populations in response to hydrological conditions: a simulation study

Increasing multi‐sectoral demands on water resources have led to water abstraction and transfer activities, and the construction of dams and embankments that have significantly altered the flood regimes of rivers throughout the world resulting in the loss of fish production and biodiversity. The current emphasis on sustainable development and biodiversity conservation is leading efforts to mitigate these impacts by means of interventions such as the release of artificial floods downstream of dams and the manipulation of water levels within impounded floodplains. Whilst much work has been done to determine the hydrological requirements for the maintenance of salmonid populations, few equivalent studies are available from which to develop criteria for the management of hydrological regimes for fishes and fisheries in large floodplain–river systems such as the Mekong. The population dynamics of fish in such rivers are believed to respond to hydrological conditions in a density‐dependent manner. An age‐structured population dynamics model incorporating sub‐models describing density‐dependent growth, mortality and recruitment was used to explore how hydrological conditions within a theoretical floodplain–river system affect the dynamics of a common floodplain–river fish species. Graphical summaries of the response of exploitable biomass to a range of different drawdown rates, dry and flood season areas and volumes, and flood season durations are presented under five different model assumptions concerning density‐dependent processes. Optimal flooding patterns are also described for the model species and theoretical river system. The patterns of predictions that emerge from the simulations provide guidelines for managing or manipulating hydrological conditions in river systems for both fixed and variable volume hydrological scenarios. As a general rule of thumb, exploitable biomass is maximized by minimizing the rate of drawdown and maximizing the flood duration and flood and dry season areas or volumes. However, experiences from dam and other hydraulic engineering projects suggest that these predictions should be treated with caution until we better understand the influence of hydrology on spawning behaviour, system primary production, and critical habitat availability. Copyright © 2004 John Wiley & Sons, Ltd.     

RECRUITMENT AND SUCCESSIONAL DYNAMICS DIVERSIFY THE SHIFTING HABITAT MOSAIC OF AN ALASKAN FLOODPLAIN

We measured plant recruitment patterns, successional dynamics, and biophysical processes on laterally expansive floodplains of the Kwethluk River, Alaska. The main channel of this gravel‐bed river frequently avulses and possesses an anabranching plan form. Fluvial processes were interactive with life history processes of riparian plants in determining initial stages of primary succession. Reproductive strategies and herbivory became important factors later in succession. We conducted plant age and compositional surveys to assess patterns of propagule deposition. We found that dispersal strategies of species were an important factor influencing recruitment patterns. Flood‐dispersed seeds resulted in even‐aged cohorts of species persistently segregated in space, based on age data. Sediment characteristics and inundation potential had little influence on seedling distributions. Recruitment was also segregated on the basis of dispersal strategy. At the heads of bars, where vegetative propagules (live drift wood) were entombed during floods, the distributions of species were random. This size‐selective nature of recruitment persisted through time. Vegetation age and distribution patterns were further diversified by the river's legacy of gravel deposition that diversified the primary successional pathway: one associated with ridges and another with swales. Interactions between these pathways and beaver herbivory initiated secondary succession. We used satellite imagery to quantify the extent of floodplain influenced by herbivory and to assess the importance of this driver of secondary succession. We also used high‐resolution aerial imagery and randomly selected sites to provide an unbiased analysis. We classified this imagery to quantify the spatial extent of herbivory and its influence on the initiation of secondary succession. The results showed, in addition to recruitment and successional dynamics, the flood‐plain habitat mosaic was diversified by the initiation of secondary succession. Patch and species composition within the vegetation mosaics were significantly different than those portions of the floodplain engaged in primary succession. Copyright © 2012 John Wiley & Sons, Ltd.     

Legacies of flood reduction on a Dryland river

The Bill Williams (Arizona) is a regulated dryland river that is being managed, in part, for biodiversity via flow management. To inform management, we contrasted riparian plant communities between the Bill Williams and an upstream free‐flowing tributary (Santa Maria). Goals of a first study (1996–1997) were to identify environmental controls on herbaceous species richness and compare richness among forest types. Analyses revealed that herbaceous species richness was negatively related to woody stem density, basal area and litter cover and positively related to light levels. Introduced Tamarix spp. was more frequent at the Bill Williams, but all three main forest types (Tamarix, Salix/Populus, Prosopis) had low understory richness, as well as high stem density and low light, on the Bill Williams as compared to the Santa Maria. The few edaphic differences between rivers (higher salinity at Bill Williams) had only weak connections with richness. A second study (2006–2007) focused on floristic richness at larger spatial scales. It revealed that during spring, and for the study cumulatively (spring and fall samplings combined), the riparian zone of the unregulated river had considerably more plant species. Annuals (vs. herbaceous perennials and woody species) showed the largest between‐river difference. Relative richness of exotic (vs. native) species did not differ. We conclude that: (1) The legacy of reduced scouring frequency and extent at the Bill Williams has reduced the open space available for colonization by annuals; and (2) Change in forest biomass structure, more so than change in forest composition, is the major driver of changes in plant species richness along this flow‐altered river. Our study informs dryland river management options by revealing trade‐offs that exist between forest biomass structure and plant species richness. Copyright © 2010 John Wiley & Sons, Ltd.     

Benchmarking Fluvial Dynamics for Process‐Based River Restoration: the Upper Rhine River (1816–2014)

Multi‐temporal analysis of river‐floodplain processes is a key tool for the identification of reference conditions or benchmarks and for the evaluation of deviations or deficits as a basis for process‐based river restoration in large modified rivers. This study developed a methodology for benchmarking fluvial processes at river segment level, focusing on those interrelations between morphodynamics (aggradation, erosion, channel shift) and vegetation succession (initial, colonization, transition) that condition habitat structure. Habitat maps of the free‐flowing Upper Rhine River downstream from Iffezheim dam (France–Germany border) were intersected with a geographic information system‐based approach. Patches showing trajectories of anthropization, changeless, progression and regression allowed for the identification of natural and human‐induced processes over almost 200 years. Before channelization, the riverine system was characterized by a shifting habitat mosaic with natural heterogeneity, high degree of surface water connectivity and equilibrium between progression and regression processes. On the other hand, the following 175 years of human interventions led to severe biogeomorphologic deficits evidenced by loss of natural processes and habitat heterogeneity, hydrological disconnection between the river and its floodplain and imbalance of progression versus regression dynamics. The main driving forces of change are found in hydromorphological impacts (channelization, regulation and hydropower plant construction). Regression processes are now almost absent and have to be the objective of process‐based river restoration measures for the studied river‐floodplain system. A sustainable view on water management and river restoration should aim at a more resilient riverine system by balancing the recovery of natural processes with societal needs. Copyright © 2016 John Wiley & Sons, Ltd.     

Targeting lateral connectivity and morphodynamics in a large river‐floodplain system: The upper Rhine River

As a consequence of historical damming and channelization, most large rivers are disconnected from their floodplains, which therefore endure severe deficits in fluvial dynamics. Regaining some degree of lateral connectivity can lead to improved geomorphological and biological interactions. Yet, it is necessary to take into account limitations posed by current uses and legislation. This study presents a methodological approach to the selection of a realistic restoration target for a heavily modified large river segment, the free‐flowing Upper Rhine River downstream of Iffezheim dam (France–Germany border), based on the analysis of the existing biogeomorphic deficits, constraints set by human uses, and previous restoration experiences. To achieve the selected restoration target, proposed scenarios include embankment removal, bank lowerings, and side channel widenings with the aim of increasing lateral hydrological connectivity and promoting morphodynamics (bank erosion in lateral channels) that allow for the renewal of floodplain habitats. Results from 2‐D hydraulic simulations allow for a sensitivity analysis, comparing the current situation with the proposed scenarios, through parameters such as shore length of side channels actively connected at both ends to the main channel (eupotamon), and shear stress as a proxy for initiation of gravel erosion. Outcomes indicate that the two proposed restoration scenarios would succeed in reconnecting side channels and in increasing areas prone to substrate erosion, while maintaining flood protection and the heaviest navigation use among European rivers. The presented approach aids in the assessment of potential large river restoration scenarios and, thus, in the discussion of water management strategies.     

Grasshoppers (Orthoptera,Saltatoria) on alpine and dealpine riverbanks and their use as indicators for natural floodplain dynamics

Gravel banks with sparse vegetation are typical habitats of braided alpine and dealpine floodplains. They are not only habitats for semiaquatic or hygrophilous organisms, but include also xerophilous elements: 17 species of grasshoppers were recorded in the floodplain of the Upper Isar (Bavaria, FRG). In the alpine region, two species (Bryodema tuberculata, Chorthippus pullus) occur only in floodplains, colonizing young gravel banks with sparse vegetation. Population dynamics and habitat selection of Bryodema tuberculata, studied on the Upper Isar for several years, are characterized by small scale movements of marked individuals between neighbouring gravel banks and fluctuations of the abundance on different sections of the gravel banks. Furthermore, the periodic desiccation of small watercourses is important for the dispersal of the females by walking. Historically widespread, today its distribution corresponds to the few remaining inundation areas. The main causes of decrease and extinction in most localities are man-made changes in floodplain dynamics. The building of retention reservoirs and the diverting of streams for hydropower influenced succession in the downstream floodplains. Most of the gravel banks with sparse vegetation changed into willow thickets or pine forests. All remaining inundation areas should be protected. Bryodema tuberculata is a good indicator for the balance between progressing succession and the reorganization of gravel banks by floods.     

Quantifying floodplain heterogeneity with field observation,remote sensing,and landscape ecology: Methods and metrics

Floodplains provide numerous ecosystem services that depend on the spatial heterogeneity, or patchiness, of the floodplain. Direct and indirect human alterations of rivers can reduce floodplain heterogeneity and function, but relatively little is known of patterns of floodplain heterogeneity in natural, fully functional floodplains. We quantify floodplain heterogeneity at four sites in the United States with the objectives of (i) developing a method of combining field measurements and remote sensing data products to calculate integrative landscape-scale metrics of floodplain spatial heterogeneity and (ii) demonstrating which metrics from landscape ecology are likely to be useful for identifying qualities of natural floodplains, differentiating floodplains, and inferring processes, based on a case study of three prairie floodplains and one beaver-modified floodplain in the continental United States. We developed a new unsupervised classification workflow that combines field data, topography, and Sentinel-2A imagery to create classified floodplains for all four field sites that could be used to calculate heterogeneity metrics. We identified six heterogeneity metrics for characterizing natural floodplain heterogeneity: aggregation index, interspersion and juxtaposition index, largest patch index, patch density, percentage of like adjacencies, and Shannon's evenness index, and these metrics capture both intermetric (variation in spatial heterogeneity between the floodplains) and intrametric variation (variation in the patterns of the metrics). Results show that natural floodplains have high evenness and interspersion and juxtaposition of classes, and we attribute this to natural flow and sediment regimes driving channel migration, erosion, deposition, vegetation succession, and active beaver modifications. Colorado floodplains show higher aggregation and lower fragmentation than the Oklahoma floodplain. We attribute this to the greater incision and lower hydrologic variability at the Oklahoma site.     

Regulated Rivers: Research & Management,Volume 17 Issue 4/5 ‘Understanding natural patterns and processes in river corridors as the basis for effective river restoration’ by J.V. Ward,K. Tockner,U. Uehlinger and F. Malard.

The incorrect version of this article was published previously. Please find the correct version, which retains the original pagination, on the next page. The publisher wishes to apologise for this mistake Running water ecology is a young science, the conceptual foundations of which were derived largely from research conducted in Europe and North America. However, virtually all European river corridors were substantially regulated well before the science of river ecology developed. While regulation of North American river systems occurred later than in European systems, river ecology also developed later. Therefore, there is a general impression of rivers as being much less heterogeneous and much more stable than they actually are in the natural state. The thesis of this paper is that established research and management concepts may fail to fully recognize the crucial roles of habitat heterogeneity and fluvial dynamics owing to a lack of fundamental knowledge of the structural and functional features of morphologically intact river corridors. Until quite recently, most concepts in river ecology were based on the implicit assumption that rivers are stable, single‐thread channels isolated from adjacent floodplains. Unfortunately, many rivers are in just such a state, but it should be recognized that this is not the natural condition. This incomplete understanding constrains scientific advances in river ecology and renders management and restoration initiatives less effective. Examples are given of the high level of spatio‐temporal heterogeneity that may be attained in rivers where natural processes still operate on a large scale. The objective of this paper is to promulgate a broader and more integrative understanding of natural processes in river corridors as a necessary prelude to effective river conservation and management. Copyright © 2001 John Wiley & Sons, Ltd.     

POTENTIAL LARGE WOODY DEBRIS RECRUITMENT DUE TO LANDSLIDES,BANK EROSION AND FLOODS IN MOUNTAIN BASINS: A QUANTITATIVE ESTIMATION APPROACH

In‐depth knowledge of the fluvial corridor and surrounding slopes and forest vegetation is needed for a better understanding of wood recruitment or inputs to rivers. The information available in Central Spain on hydrogeomorphic processes and forest distribution enabled the evaluation of potential wood recruitment from three sources: landslides, bank erosion and fluvial transport during floods on a regional scale. The method presented here is based on a geographical information system (GIS) and on multi‐criteria and multi‐objective assessment using fuzzy logic principles. First, the areas potentially affected by landslides, bank erosion and floods were delineated, and a vegetation analysis was carried out to obtain the vegetation resistance and forest density. Several scenarios were proposed based on the process frequency and severity. Using this method, the volume of potentially available wood can be estimated for each scenario. Fourteen river basins in populated areas were selected for further analyses and field survey. Observations of in‐stream storage of woody debris and tree disturbances were used to interpret the woody debris dynamics throughout the watershed and validate the obtained results. This method offers a suitable approach to define a watershed's capacity to recruit wood material to streams by delineating the source areas and estimating the order of magnitude of the wood volume in each case. The results may be useful to characterize the dynamics of woody debris from the perspective of the potential hazard of its transport during floods, and they can also be used for forest and river management and restoration. Copyright © 2012 John Wiley & Sons, Ltd.