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1.
- 1 The planning, design and evaluation of a restoration project should be guided largely by an understanding of past channel changes.
- 2 A historical analysis can sometimes reveal underlying causes of channel change and document prior habitat conditions, both useful in setting appropriate objectives for restoration.
- 3 Restoration planning should address the historical causes and patterns of channel degradation that cannot be detected by examining current conditions alone. Moreover, ongoing adjustments in the channel and changes in the catchment must be understood when interpreting channel changes following construction of restoration projects.
- 4 Changes in channel form (and the independent geomorphological variables of run-off and sediment load from the catchment) can be documented from a variety of sources, including historical maps, boundary lines, aerial photography, bridge and pipeline surveys, gauging records, field evidence and archival sources. Historical riparian vegetation, and use by fish and wildlife, may also be documented from early survey records, photographs and written accounts.
- 5 Historical analysis should cover an area large enough to capture all events potentially influencing the project reach. The entire catchment upstream should be examined to identify events affecting the flow regime and sediment load, such as deforestation or dam construction. For channels in erodible alluvium, the study should include the channel downstream to the first stable grade control to capture events whose effects may propagate upstream, such as channelization or base lowering.
- 6 Application of historical channel analysis to the San Luis Rey River in California served as a basis for evaluating the potential for (and hydrological constraints upon) riparian restoration.
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David A. Schumann Katie N. B. Graeb Jarrett Pfrimmer Joshua D. Stafford Steven R. Chipps 《水产资源保护:海洋与淡水生态系统》2021,31(9):2481-2495
- Landscape homogenization and the removal of riparian areas have altered stream ecosystems worldwide. Numerous conservation programmes attempt to improve water quality and increase instream habitat heterogeneity to elicit desired biological responses. However, the effectiveness of many conservation efforts on isolated stream fragments remains unknown, especially in grassland regions.
- The effects of grassland conservation practices and the re-establishment of riparian corridors in the James River basin, South Dakota (USA) on stream water quality, habitat availability and aquatic macroinvertebrate and fish assemblages were studied in an agriculturally dominated prairie landscape.
- Grassland conservation efforts may have repaired riparian condition, reduced turbidity and created more diverse instream habitat complexes at conservation sites based on comparisons with paired reference reaches. Reference sites were relatively homogeneous, with prevalent siltation, bank erosion and disturbances to the riparian vegetation. Owing to significant riparian vegetation development, overhanging and aquatic vegetation, benthic detritus and woody materials were significantly more common at conservation reaches.
- Restoration efforts that assume ‘if you (re-)build it, they will come’ (i.e. the ‘field of dreams’ hypothesis) underestimate other important barriers to biodiversity restoration in dynamic, grassland riverscapes. Although aquatic organisms in grassland ecosystems are adapted to rapidly inhabit available habitats, the development of niche space at conservation reaches did not directly result in colonization by aquatic life.
- Grassland management actions did not address stream connectivity issues or overcome land use influences elsewhere in the riverscape that may govern the responses of aquatic macroinvertebrates and fish. Stream fragmentation and continuing, damaging land use patterns seemed to exceed the positive effects of restoring isolated stream reaches in these heavily degraded catchments. Catchment-scale management strategies that combine reach-level restoration actions with efforts to improve connectivity are likely to be more successful in degraded riverscapes.
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- 1 Throughout the Temperate Forest biogeographical zone, river valleys were once heavily wooded. Fallen trees had a major impact upon river systems by ponding water and storing sediments, and valley floors were characterized by extensive wetlands with networks of minor channels linking to the main channel. Concern for environmental conservation and for the rehabilitation of damaged aquatic ecosystems has led to research on the links between river channel dynamics and vegetation, and an interest in the use of dead wood for environmentally sensitive engineering approaches to river management.
- 2 Accumulations of coarse woody debris (CWD) have an impact on the hydrological, hydraulic, sedimentological, morphological and biological characteristics of river channels. These impacts are very significant for the stability and biological productivity of river channels in forested catchments.
- 3 As a result of the geomorphological and ecological importance of CWD in river channels in forested catchments, such debris requires careful management. In particular indiscriminate removal of CWD should be avoided.
- 4 In the context of commercial forestry, a sequence of linked management options can be employed to control sediment and organic matter transport within river systems and to enhance channel stability and physical habitat diversity. These management options include selective removal of less stable debris, addition of debris to the river where the natural supply is inadequate, the maintenance of buffer strips of riparian trees which can act as a source of CWD, and the active management of woodland buffer strips to provide a wide range of physical habitat characteristics including light, temperature, flow, sediment transport and substrate conditions, thereby promoting high biological diversity within the river environment.
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Torben Moth Iversen Brian Kronvang Bent Lauge Madsen Peter Markmann Mogens Bjrn Nielsen 《水产资源保护:海洋与淡水生态系统》1993,3(2):73-92
- 1. Prior to 1983 the Danish legislation concerning streams gave priority to drainage of water. The revision of The Watercourse Act gave balanced priority to drainage of water and environmental quality, focusing on an ecologically more appropriate maintenance practice and giving special provisions for stream restoration activities.
- 2. Different measures of single structure restoration have been used, the most common being replacement of weirs, dams or other obstacles by rapids, establishment of salmonid spawning grounds, and installation of new or improved fish ladders.
- 3. The most common stream channel restoration method is integrated use of a number of single structure measures. Establishment of a two-stage channel and re-opening of small piped streams have also been used. Stream valley restoration includes restoration of old meanders or establishment of a new sinuous channel and involves the adjacent riparian areas.
- 4. The changed stream maintenance practice involves a new strategy for dredging and cutting of weeds and bank vegetation in order to minimize the ecological damage caused by keeping a reasonable discharge capacity. In 1990, environmentally acceptable weed-cutting was performed in 37% of all municipal streams and the bank vegetation was left uncut in a third of the streams. Similarly, more than half of the county streams were maintained using hand scythes and in 74% of the streams the bank vegetation was left uncut.
- 5. Quantitatively, stream restoration has contributed little to the general improvement of Danish streams compared with changed maintenance practice. Stream restoration projects create public interest in the environmental quality of streams, but major improvements in the physical properties of Danish streams depend on future maintenance practice.
- 6. Due to major changes predicted in Danish agriculture many riparian areas and wetlands will reappear and the natural or semi-natural physical properties of streams will be re-established by natural processes or changed in maintenance practice. However, there will still be large areas with intensive agriculture, where environmental and agricultural interests must be balanced. The Danish experience has shown that this is possible.
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- 1. Despite a growing number of river restoration projects in Central Europe targeting hydromorphological improvements, it is still uncommon to evaluate the effects of restoration. Hydromorphological diversity in straightened, single‐channel sections was compared with restored or naturally developed multiple‐channel sections in German mountain rivers to identify parameters suitable for judging conservation value or restoration success.
- 2. Seven multiple‐channel sections were compared with nearby straightened single‐channel sections. Six hydromorphological parameters at macro‐, meso‐ and micro‐scales were recorded with transect point protocols, including aquatic, terrestrial and transient areas and width of channel features (main and secondary channels, sidearms, standing water bodies, bars, banks, floodplains and embankments). Depth, velocity and substrate type were measured at 400 points per river section. With these data 12 metrics were calculated, to provide comparison between the sections.
- 3. All macro‐ and meso‐scale parameters were well differentiated between single‐channel and multiple‐channel sections: mean channel width and shoreline length increased by factors of 2.1 and 2.4, respectively; the average number of channel feature types increased from two to 10 per section.
- 4. Micro‐scale parameters, such as velocity and depth variance, were significantly different between single‐channel sections and most multiple‐channel sections. Substrate composition was more diverse in the restored sections; the share of the major substrate was on average reduced from 75% to 62%. The Spatial Diversity Index described differences in substrate patterns best. The individual parameters correlated only within scales, but rarely between them.
- 5. Rapid assessment of restoration success or judgement of conservation value is made possible by combining simple macro‐ and meso‐scale parameters, e.g. increase of overall width or of transient areas, and presence of bars and islands. Increase in aquatic area and diversity of habitats are the most appropriate micro‐scale parameters required to evaluate habitat suitability for aquatic organisms. For depth and velocity data, variance should be analysed.
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Christina M. Cianfrani S. Mažeika P. Sullivan W. Cully Hession Mary C. Watzin 《水产资源保护:海洋与淡水生态系统》2009,19(2):147-156
- 1. Stream classification systems are widely used in stream management and restoration. Whereas the principal morphological types of these classification systems are increasingly recognized for their ecological connections, the roles of intermediate and mixed morphologies are still poorly understood, yet may be biologically significant.
- 2. Twenty‐five stream reaches in north‐western Vermont were classified by channel morphology to determine whether fish community diversity differed among pool‐riffle, mixed (i.e. pool‐riffle/cascade, pool‐riffle/other) and forced pool‐riffle stream morphological groups. Stream reach surveys included cross‐sectional surveys, longitudinal profiles, bed substrate characterization, and fish surveys.
- 3. Three fish community diversity measures were calculated: (1) species richness (S); (2) Shannon–Weaver Index (H′); and (3) Simpson's Index (1/D). Multivariate analysis of covariance (MANCOVA) followed by analysis of variance (ANOVA) were used to explore potential differences in fish diversity among stream morphological groups. Fish diversity was significantly different for all three community diversity measures (P?0.05), with pool‐riffle/cascade morphology consistently exhibiting the greatest fish diversity and forced pool‐riffle the lowest.
- 4. These results suggest that fish community diversity is significantly associated with distinct channel morphologies. Generally, pool‐riffle/cascade and pool‐riffle/other stream morphological groups supported habitats that fostered greater species diversity than more homogeneous and uniform pool‐riffle reaches. The observed patterns of diversity are likely to be the result of habitat patches created by variations in flow and other physical characteristics in reaches of mixed morphologies.
- 5. These results support fish sampling schemes that incorporate morphological heterogeneity, such as proportional‐distance designation. Sampling strategies that focus on homogeneous reaches may underestimate diversity, and misrepresent stream condition when fish community data are used in indices of biological integrity (IBIs). Reaches of mixed stream morphologies should be recognized as areas of biological importance in stream and catchment management and in conservation efforts.
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- 1. River restoration is now widely undertaken and may be considered an increasingly important aspect of river management. Recent developments in European legislation (Habitats Directive and the Water Framework Directive) should give further impetus to river restoration across EU member states, as this legislation places greater emphasis on the processes that support river ecology.
- 2. Traditional river restoration approaches have been reach‐focused and opportunistic, capitalizing on flood defence works and the cooperation of sympathetic landowners.
- 3. Furthermore, many schemes have been species‐ or habitat‐driven and, thus, have sought to recreate channel forms believed to be favoured by particular species or associated with particular habitats. Such approaches have not always given due attention to the underlying geomorphological processes that create channel form and, consequently, the schemes have not been self‐sustaining, requiring continued management input.
- 4. Consistent with the ethos of the Water Framework Directive, an eco‐hydromorphic approach to river restoration is proposed here. This approach views spatial and temporal heterogeneity as fundamental characteristics of fluvial systems and advocates recreating a framework within which natural processes, such as sediment transport and nutrient dynamics, can occur.
- 5. Mesoscale habitat approaches are considered as one possible way to plan and achieve this framework, providing the potential to link the wide range of spatial and temporal scales that characterize river systems.
- 6. It is argued that river restoration will only be sustainable if it is undertaken within a process‐driven and strategic framework with inputs from a wide range of specialists. Such an approach needs to be reviewed constantly in light of appraisal and monitoring of previous river restoration schemes.
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M. Worth Pugh Gary Pandolfi Thomas Franklin Michael M. Gangloff 《水产资源保护:海洋与淡水生态系统》2021,31(3):494-503
- Freshwater communities are threatened by the conversion of natural landscapes for urban and agricultural purposes. Changes to land use may disrupt stream nutrient and geomorphological processes and reduce water quality, increase sedimentation, and decrease habitat heterogeneity eventually leading to species loss and decreases in ecosystem productivity. Endemic species are frequently at greater risk of habitat-mediated fragmentation and extirpation due to their constrained distributions.
- The Kanawha darter (Etheostoma kanawhae) is an understudied fish endemic to the New River Drainage in North Carolina and Virginia, USA. To investigate the potential effect(s) of land-use change on Kanawha darters, naïve occupancy was modelled using instream habitat characteristics and upstream forest cover.
- Generalized linear models revealed that instream habitat and forest cover are reliable predictors of Kanawha darter site occupancy. Specifically, models demonstrated that occupancy increased in reaches with reduced stream width, velocity, and bedrock substrate but higher concentrations of coarse woody material. Kanawha darter occupancy was also positively associated with the extent of forest cover in upstream catchments.
- Although Kanawha darters are not currently considered imperilled, most populations occurred in isolated reaches separated by large sections of unoccupied habitat. Continuing ex-urban development in riparian zones is likely to be the primary threat to Kanawha darters and other endemic species in this catchment. Resource managers and stakeholders should preserve forest cover in headwaters and occupied tributaries and protect or restore riparian zones along the main-stem South and North Forks of the New River to preserve high-quality habitat and enhance connectivity among isolated Kanawha darter populations.
- As human populations in montane regions continue to grow, there is a need to understand how land-use change affects endemic freshwater species. This study further supports the importance of retaining forest cover as an effective strategy for protecting and restoring populations of endemic fishes in high-gradient streams.
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- 1. Classification is a useful tool for researchers and managers wishing to group functionally similar sites or to identify unique or threatened habitats. A process‐based river classification scheme that successfully integrates physical and biological aspects of lotic form and function would enhance conservation and restoration efforts by allowing more meaningful comparisons among sites, and improving functional understanding of lotic ecosystems.
- 2. The River Styles framework provides a geomorphological river characterization scheme in which assemblages of geomorphic units vary for differing River Styles, presenting differing arrays of aquatic habitat diversity for each style.
- 3. The ecological significance of the River Styles framework is tested by comparing the macroinvertebrate assemblages and habitat characteristics of pool and run geomorphic units for three different River Styles on the north coast of New South Wales, Australia.
- 4. Multivariate ordinations and analysis of similarity (ANOSIM) revealed that macroinvertebrate community structure differed between Bedrock‐Controlled Discontinuous Floodplain rivers and Gorge rivers, and between Bedrock‐Controlled Discontinuous Floodplain and Meandering Gravel Bed rivers, especially in pools. Differences between Gorge and Meandering Gravel Bed rivers were less apparent, largely due to variations within the Meandering Gravel Bed rivers group.
- 5. The variability in macroinvertebrate assemblage structure among geomorphic units was most strongly related to variability in substrate and hydraulic variables. Substrate composition differed significantly among all River Styles and geomorphic units, but other habitat variables showed few consistent differences among River Style groups.
- 6. These results suggest that the ecological similarity of macroinvertebrate communities within River Styles may presently be limited because some important large‐scale drivers of local habitat conditions are not included in River Styles designations. Integrating River Styles classification with other large‐scale variables reflecting stream size, temperature and hydrological regime may produce a process‐based physical classification capable of identifying river reaches with similar ecological structure and function.
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- 1. Incised stream channel aquatic habitats typically are severely degraded. After the primary knickpoints or knickzones have passed, base flows are limited to shallow channels flanked by sandy berms within the enlarged high-flow channel. Riparian vegetation, woody debris and pool habitat are in short supply, and stream systems become disengaged from their floodplains.
- 2. We hypothesized that habitat recovery might be accelerated in channels that have incised and are regaining equilibrium through deposition of sandy berms by placing rock spurs in the channel and by planting woody vegetation on the berms. On the basis of literature review and a pilot study, planting designs were developed for a large-scale field experiment: 2550 1.5 m long cuttings of native willow (Salix spp.) 2–25 cm in diameter were planted 1–1.2 m deep along the base-flow channel of an incised stream. A ridge of stone was placed on the water side of the plantings, and 17 rock spurs were constructed by extending existing spur dikes from the opposite bank.
- 3. Woody cover along the treated bank increased from 38% to 66% of bankline after one growing season. Survival of individual plantings was reduced from an estimated 60% to an observed 34% by competition from the exotic kudzu vine, Pueraria lobata. Mean depth and mean scour hole depth, corrected for stage variation, increased 44% and 82%, respectively. Mean scour hole width increased 130%. The mean length of fish and the number of fish species approximately doubled, while the total weight of fish captured by a unit of sampling effort increased by an order of magnitude.
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- 1. Small streams are increasingly under pressure to meet water needs associated with expanding human development, but the hydrologic and ecological effects are not commonly described in scientific literature.
- 2. To evaluate the potential effects that surface water abstraction can have on flow regime, scientists and resource managers require tools that compare abstraction to stream flow at ecologically relevant time scales.
- 3. The classic water balance model was adapted to evaluate how small instream diversions can affect catchment stream‐flow; the adapted model maintains the basic mass balance concept, but limits the parameters and considers surface water data at an appropriate timescale.
- 4. This surface water balance was applied to 20 Russian River tributaries in north‐central California to evaluate how recognized diversions can affect stream flow throughout the region.
- 5. The model indicates that existing diversions have little capacity to influence peak or base flows during the rainy winter season, but may reduce stream flow during spring by 20% in one‐third of all the study streams; and have the potential to accelerate summer intermittence in 80% of the streams included in this study.
- 6. The surface water balance model may be especially useful for guiding river restoration from a hydrologic perspective: it can distinguish among streams with high diversion regimes that may require more than just physical channel restoration to provide ecological benefits, and can illustrate the extent to which changing the diversion parameters of particular water users can affect the persistence of a natural flow regime.
- 7. As applied to Russian River tributaries, the surface water balances suggest that reducing demand for stream flow in summer may be as important as physical channel restoration to restoring anadromous salmonids in this region.
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- 1. Allochthonous carbon is the basis of the detrital food web in low‐order, warmwater stream ecosystems, and stream‐bed sediments typically function as carbon reservoirs. Many of the same factors that govern carbon input and storage to streams (e.g. riparian vegetation, large wood, heterogeneous boundaries) have also been identified as key attributes of stream fish habitat.
- 2. Effects of channel incision on sand‐bed stream carbon reservoirs and indices of biological integrity (IBIs) based on fish collections were examined for four streams exhibiting a range of incisement in northern Mississippi. Observed mean C concentrations (mass percentage) ranged from 0.24±0.36% for a non‐incised stream to only 0.01±0.02% for a severely incised channel, and were not correlated with large wood (LW) density, perhaps because LW density at one site was elevated by a habitat rehabilitation project and at another site by accelerated inputs from incision‐related riparian tree fall. Fish IBI was positively correlated with bed C (r=0.70, p=0.003), and IBIs for reference streams were more than 50% greater than those computed for the most severely degraded sites.
- 3. More testing is needed to determine the efficacy of stream bed C as an indicator, but its importance to warmwater stream ecosystems, and the importance of covarying physical and hydrologic conditions seems evident.
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Biodiversity values of remnant freshwater floodplain lagoons in agricultural catchments: evidence for fish of the Wet Tropics bioregion,northern Australia 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Angela H. Arthington Paul C. Godfrey Richard G. Pearson Fazlul Karim Jim Wallace 《水产资源保护:海洋与淡水生态系统》2015,25(3):336-352
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