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  • 1.
    Hoppenreijs, Jacqueline H. T.
    et al.
    Department of Environmental and Life Sciences, Karlstad University, Karlstad, Sweden.
    Marker, Jeffery
    Department of Environmental and Life Sciences, Karlstad University, Karlstad, Sweden.
    Maliao, Ronald J.
    Pál Juhász-Nagy Doctoral School of Biology and Environmental Sciences, University of Debrecen, Debrecen, Hungary; Community Resiliency and Environmental Education Development (CREED) Foundation, Iloilo, Philippines.
    Hansen, Henry H.
    Department of Environmental and Life Sciences, Karlstad University, Karlstad, Sweden.
    Juhász, Erika
    Institute of Ecology and Botany, Centre for Ecological Research, Vácrátót, Hungary; National Laboratory for Health Security’, Centre for Ecological Research, Vácrátót, Hungary.
    Lõhmus, Asko
    Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia.
    Altanov, Vassil Y.
    Department of Community and Ecosystem Ecology, Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany.
    Horká, Petra
    Institute for Environmental Studies, Faculty of Science, Charles University, Prague, Czech Republic.
    Larsen, Annegret
    Department of Soil Geography and Landscape, Wageningen University & Research, Wageningen, Netherlands.
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Runnel, Kadri
    Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia.
    Piccolo, John J.
    Department of Environmental and Life Sciences, Karlstad University, Karlstad, Sweden.
    Magurran, Anne E.
    Centre for Biological Diversity, School of Biology, University of St Andrews, St Andrews, United Kingdom.
    Three major steps toward the conservation of freshwater and riparian biodiversity2023In: Conservation Biology, ISSN 0888-8892, E-ISSN 1523-1739, article id e14226Article in journal (Refereed)
    Abstract [en]

    Freshwater ecosystems and their bordering wetlands and riparian zones are vital for human society and biological diversity. Yet, they are among the most degraded ecosystems, where sharp declines in biodiversity are driven by human activities, such as hydropower development, agriculture, forestry, and fisheries. Because freshwater ecosystems are characterized by strongly reciprocal linkages with surrounding landscapes, human activities that encroach on or degrade riparian zones ultimately lead to declines in freshwater–riparian ecosystem functioning. We synthesized results of a symposium on freshwater, riparian, and wetland processes and interactions and analyzed some of the major problems associated with improving freshwater and riparian research and management. Three distinct barriers are the lack of involvement of local people in conservation research and management, absence of adequate measurement of biodiversity in freshwater and riparian ecosystems, and separate legislation and policy on riparian and freshwater management. Based on our findings, we argue that freshwater and riparian research and conservation efforts should be integrated more explicitly. Best practices for overcoming the 3 major barriers to improved conservation include more and sustainable use of traditional and other forms of local ecological knowledge, choosing appropriate metrics for ecological research and monitoring of restoration efforts, and mirroring the close links between riparian and freshwater ecosystems in legislation and policy. Integrating these 3 angles in conservation science and practice will provide substantial benefits in addressing the freshwater biodiversity crisis.

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    fulltext
  • 2.
    Jørgensen, Dolly
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Renöfält, Brigitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Damned if you do, dammed if you don’t: debates on dam removal in the Swedish media2013In: Ecology and Society, E-ISSN 1708-3087, Vol. 18, no 1Article in journal (Refereed)
    Abstract [en]

    Dam removal is an increasingly common practice. Dams are removed for various reasons with safety, economics, and ecosystem restoration being the most common. However, dam removals often cause controversy. Riparian land owners and local communities often have a negative view on removal and the reasons why vary. It may be loss of recreational benefits like swimming and boating, loss of cultural and historical context tied to the dam, or fear that removal may have a negative effect on aesthetic values. Since controversies are often picked up by local media, and media in itself is an important channel to build support around a cause, the way dam removals are reported and discussed is likely to influence the debate. In this article, we examine the ways in which proponents and opponents of dam removal frame the services provided by two contrasting ecosystems—an existing dam and the potential stream without a dam—by performing a discourse analysis of the reasons given for removal and the reasons presented for the dam to remain in place. Our source material includes web-based newspaper articles and public comments on those articles in four dam removal controversies in Sweden. Our results indicate that public opposition is not based on knowledge-deficiency where more information will lead to better ecological decision-making, as is sometimes argued in dam removal science; it is instead a case of different understandings and valuation of the environment and the functions it provides.

  • 3.
    Kuglerova, Lenka
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ågren, Anneli
    Laudon, Hjalmar
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Groundwater discharge creates hotspots of riparian plant species richness in a boreal forest stream network2014In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 95, no 3, p. 715-725Article in journal (Refereed)
    Abstract [en]

    Riparian vegetation research has traditionally focused on channel-related processes because riparian areas are situated on the edge of aquatic ecosystems and are therefore greatly affected by the flow regime of streams and rivers. However, due to their low topographic position in the landscape, riparian areas receive significant inputs of water and nutrients from uplands. These inputs may be important for riparian vegetation, but their role for riparian plant diversity is poorly known. We studied the relationship between the influx of groundwater (GW) from upland areas and riparian plant diversity and composition along a stream size gradient, ranging from small basins lacking permanent streams to a seventh-order river in northern Sweden. We selected riparian sites with and without GW discharge using a hydrological model describing GW flow accumulation to test the hypothesis that riparian sites with GW discharge harbor plant communities with higher species richness. We further investigated several environmental factors to detect habitat differences between sites differing in GW discharge conditions. Vascular plant species richness was between 15% and 20% higher, depending on the spatial scale sampled, at riparian sites with GW discharge in comparison to non-discharge sites, a pattern that was consistent across all stream sizes. The elevated species richness was best explained by higher soil pH and higher nitrogen availability (manifested as lower soil C/N ratio), conditions which were positively correlated with GW discharge. Base cations and possibly nitrogen transported by groundwater may therefore act as a terrestrial subsidy of riparian vegetation. The stable isotopes N-15 and C-13 were depleted in soils from GW discharge compared to non-discharge sites, suggesting that GW inputs might also affect nitrogen and carbon dynamics in riparian soils. Despite the fact that many flows of water and nutrients reaching streams are filtered through riparian zones, the importance of these flows for riparian vegetation has not been appreciated. Our results demonstrated strong relationships between GW discharge, plant species richness and environmental conditions across the entire stream size gradient, suggesting that both river hydrology and upland inputs should be considered to fully understand riparian vegetation dynamics.

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    fulltext
  • 4.
    Kuglerová, Lenka
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Sponseller, Ryan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Laudon, Hjalmar
    Sveriges lantbruksuniversitet.
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Local and regional processes determine plant species richness in a river-network metacommunity2015In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 96, no 2, p. 381-391Article in journal (Refereed)
    Abstract [en]

    River systems form dendritic ecological networks that influence the spatial structure of riverine communities. Few empirical studies have evaluated how regional, dispersal-related processes and local habitat factors interact to govern network patterns of species composition. We explore such interactions in a boreal watershed and show that riparian plant species richness increases strongly with drainage size, i.e., with downstream position in the network. Assemblage composition was nested, with new species successively added downstream. These spatial patterns in species composition were related to a combination of local and regional processes. Breadth in local habitat conditions increased downstream in the network, resulting in higher habitat heterogeneity and reduced niche overlap among species, which together with similar trends in disturbance, allows more species to coexist. Riparian edaphic conditions were also increasingly favorable to more species within the regional pool along larger streams, with greater nitrogen availability (manifested as lower C:N) and more rapid mineralization of C and N (as indicated by ratios of stable isotopes) observed with downstream position in the network. The number of species with capacity for water dispersal increased with stream size providing a mechanistic link between plant traits and the downstream accumulation of species as more propagules arrive from upstream sites. Similarity in species composition between sites was related to both geographical and environmental distance. Our results provide the first empirical evidence that position in the river network drives spatial patterns in riparian plant diversity and composition by the joint influence of local (disturbance, habitat conditions, and breadth) and regional (dispersal) forces.

  • 5.
    Lejon, Anna G.C.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Malm Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Conflicts associated with dam removal in Sweden2009In: Ecology and Society, E-ISSN 1708-3087, Vol. 14, no 2, p. 4-Article in journal (Refereed)
    Abstract [en]

    The increasing number of deteriorating old dams that need renovation or have lost their function make dam removal a viable management option. There are at least four major reasons for dam removal: safety, law and policy, economy, and ecology. Here we discuss 17 Swedish dams that were recently considered for removal. Because dam removal usually causes controversy, dam removal initiatives may succeed, fail, or result in a compromise such as a bypass channel for migrating fish. We identify and discuss three major obstructions to dam removal: funding, cultural-historical values, and threatened species. To facilitate dam removal, the reasons for, and the effects of, dam removal must be carefully explained, and the public and stakeholders must be kept informed. In complicated cases in which compromise solutions may be the most feasible outcome, the integration of the knowledge of different stakeholders is crucial. The involvement of diverse stakeholders increases their willingness to find compromises, thus avoiding conflicts and failures.

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    Lejon et al_EcolSoc2009
  • 6.
    Lejon, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Malm Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Dam removal effects on riparian vegetationManuscript (preprint) (Other academic)
    Abstract [en]

    Dams cause substantial damage to stream and river landscapes, especially because of flow regulation and channel fragmentation that constrain environmental structures and processes. Dam removal, on the other hand, initiates succession of plant communities as a response to new morphological and hydrological conditions in the channel. We studied the vegetation in riparian reaches upstream and downstream of a dam construction in the Nissan stream in southern Sweden before and after its removal, using a Before-After-Control-Impact (BACI) design. We monitored the vegetation and different environmental variables at three different water levels (summer low, middle and spring high) in the impoundment, downstream of the dam, as well as in an unimpacted reach located within the same river system upstream of the area affected by the dam. Following dam removal, plant colonisation was fast on newly exposed soils in the former impoundment and species richness increased slightly without major changes of the dominant species. The reach downstream of the dam exhibited minor changes after dam removal, comparable to those in the reference reach. The vegetation response implies that the post-removal vegetation in the impoundment area was more similar to that of the previous impoundment than to that of the reference reach, suggesting low seed rain and local recruitment.

  • 7.
    Lejon, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Malm Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Succession of riparian plants following dam removal in a boreal stream in central SwedenManuscript (preprint) (Other academic)
    Abstract [en]

    Worldwide there are numerous aging and non-performing dams that may face removal, for economic or other reasons.  Dam removal initiates succession of plant and animal communities as a response to new morphological and hydrological conditions in the channel. We studied the succession of plant communities in riparian reaches upstream and downstream of a recently removed dam in central Sweden over 3 years. We monitored the vegetation development at each site and compared it with a reference site in an unimpacted upstream reach. The two reaches located in the former reservoir developed new riparian zones following dam removal. Plant colonisation in the new riparian zone was fast and species composition became increasingly similar to that of the reference reach. Dam removal largely restored species composition in the riparian zones that were formed in the previous reservoir, indicating that an appropriate species pool was available and that conditions for natural regeneration of riparian vegetation were sufficient.  However, a significant decline in species richness in the downstream reach following dam removal may imply that the upstream and downstream effects of removal may differ and that the removal itself may have disturbed the reach downstream of the former dam. Although remaining timber floating structures and four hydroelectric dams upstream may hamper a more complete vegetation recovery we foresee many years of riparian vegetation development before the successional processes slow down.

  • 8.
    Malm Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Removal of dams2006In: Dams under debate / [ed] Birgitta Johansson, Björn Sellberg, Stockholm: Forskningsrådet Formas , 2006, p. 107-114Chapter in book (Other academic)
  • 9.
    Malm Renöfält, Birgitta
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Lejon, Anna G.C.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jonsson, Micael
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Long-term taxon-specific responses of macroinvertebrates to dam removal in a mid-sized Swedish stream2013In: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 29, no 9, p. 1082-1089Article in journal (Other academic)
    Abstract [en]

    Dam removal to restore ecologically impaired rivers is becoming increasingly common. While the target often is to facilitate fish migration, dam removal has also been assumed to benefit other types of organisms. Because few studies thus far deal with effects of dam removal on stream macroinvertebrates, and because results have been equivocal, we investigated both short- and longer-term dam-removal effects on downstream macroinvertebrate communities. We did this in a before-and-after study of the removal of a dam located in a south Swedish stream. We sampled the benthic fauna 6 months prior to dam removal and both 6 months and 3.5 years after the dam was removed. We compared species composition, taxonomic richness, total densities, and densities of macroinvertebrate groups before and after dam removal and between downstream and reference sites. We found that dam removal reduced some macroinvertebrate taxa at the downstream site, but we found no effect on community composition. While this corroborates results from previous short-term studies, we also found a reduction of taxonomic richness and that some dam-removal effects persisted or even increased over time. The most likely explanation for the suppression of benthic macroinvertebrate richness following dam removal is a significantly increased sediment transport from the former reservoir, and a subsequent loss of preferred substrates. Our results indicate that adverse dam-removal effects may be long-lasting, but taxon-specific. We therefore call for longer-term studies on a variety of organisms to better understand how dam removal may influence downstream macroinvertebrate communities.

  • 10.
    Malm-Renöfält, Birgitta
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Hjerdt, Niclas
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Restaurering av vattendrag i ett landskapsperspektiv: – en syntes av ”Second international Symposium on Riverine Landscapes”2006Report (Other academic)
  • 11.
    Malm-Renöfält, Birgitta
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Effects of hydropower generation and opportunities for environmental flow management in Swedish riverine ecosystems2010In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 55, no 1, p. 49-67Article in journal (Refereed)
    Abstract [en]

    Hydropower is often presented as a clean and renewable energy source that is environmentally preferable to fossil fuels or nuclear power. Hydropower production, however, fundamentally transforms rivers and their ecosystems by fragmenting channels and altering river flows. These changes reduce flow velocity and the number of rapids, and reduce or alter wetland, floodplain and delta ecosystems. Dams disrupt dispersal of riverine organisms and sediment dynamics and may alter riverine biodiversity composition and abundance. Freshwater ecosystems now belong among the world's most threatened ecosystems.

    Water managers are beginning to recognise the need to combine demands for social and economic development with the protection of the resource base on which socioeconomic benefits rely. Environmental flows can help to balance ecosystem and human needs for water, both when constructing new dams and in re-licensing existing dams.

    We briefly review the impacts of hydropower generation on freshwater ecosystems by discussing different types of dams and development, and by providing examples from Sweden of how environmental effects of hydropower production could be mitigated. Special emphasis is given to flow regulation through re-operation of dams.

    Regulated rivers in Sweden were developed with little consideration of ecological effects, with most dams lacking migration pathways or minimum flow releases. There is thus a substantial potential for improvement of ecological conditions, such as naturalisation of flow regimes and reestablishment of connectivity, in regulated river reaches but technical hurdles imply major challenges for rehabilitation and mitigation. Most regulated rivers consist of cascades of consecutive reservoirs and impoundments, further constraining possible actions to improve ecological conditions.

    Most environmental mitigation measures require flow modifications to serve ecosystems, implying reduced power production. An important challenge for river management is to identify situations where measures involving relatively small production losses can have major ecological advantages.

    Climate change during the 21st century is expected to increase runoff in northern and central Sweden and make the annual hydrograph more similar to variation in electricity demand, i.e. a lower spring flood and increased run-off during winter months. This could provide opportunities for operating dams and power stations to the benefit of riverine ecosystems. On the other hand, demands to produce hydropower are likely to increase as fossil fuels are phased out, leading to increased pressures on free-flowing rivers and aquatic ecosystems.

  • 12.
    Malm-Renöfält, Birgitta
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Merritt, David M.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Connecting variation in vegetation and stream flow: the role of geomorphic context in vegetation response to large floods along boreal rivers2007In: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 44, no 1, p. 147-157Article in journal (Refereed)
    Abstract [en]
    1. Flooding governs riparian plant diversity along boreal rivers but the ecological role of extreme floods is only partly understood. We studied the dynamics of riparian plant composition and richness in the free-flowing Vindel River in northern Sweden, and the importance of reach type in sustaining high species richness.
    2. We conducted three surveys of riparian plant species richness over a period of two decades. The first and last of these surveys were conducted 1–3 years after significant flooding and the second was carried out after a period of more moderate flooding.
    3. Our results suggest that extreme floods reduce riparian plant species richness in tranquil (slow-flowing) reaches but that a subsequent period of less extreme flood events facilitates recovery. Tranquil river reaches were also more prone to invasion by ruderal species following major floods. Species richness in turbulent reaches (rapids and runs) remained constant during all surveys. One possible explanation for this pattern is that tranquil reaches become more anoxic during floods because they have more fine-grade soils with lower hydraulic conductivity than turbulent reaches. Anoxic conditions may cause stress and plant death, opening up space for colonization. Turbulent reaches maintain a better oxygenation in the root zone of plants through high groundwater turnover, reducing negative effects of prolonged floods.
    4. The fact that turbulent reaches preserved species richness regardless of flood magnitude suggests that they are important for the resistance of riparian ecosystems to prolonged inundation. In contrast, tranquil reaches, with a higher water-holding capacity, might instead maintain their species richness during drought periods.
    5. Synthesis and applications. Our findings highlight the importance of spatial and temporal variation in riverine plant species richness and composition. To conserve these habitats at a landscape scale, a full range of reach types is necessary to allow for recovery in reaches where species richness has declined. To maintain healthy riparian zones, river managers should focus restoration efforts on interactions between hydrology, geomorphology and biota.
  • 13.
    Malm-Renöfält, Birgitta
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Merritt, David
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Connecting variation in vegetation and streamflow: the functions of large floods for riparian plant diversity and composition in boreal riversManuscript (preprint) (Other academic)
  • 14.
    Malm-Renöfält, Birgitta
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Landscape scale effects of disturbance on riparian vegetation2008In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 53, no 11, p. 2244-2255Article in journal (Refereed)
    Abstract [en]

    1. Differing responses in riparian species richness and composition to disturbance have been reported as a possible explanation for the differences along and between rivers. This paper explores the role of physical disturbance in shaping landscape-scale patterns of species distribution in riparian vegetation along a free-flowing river in northern Sweden.

    2. To test whether sensitivity to disturbance varies across large landscapes, we experimentally disturbed riparian vegetation along an entire, free-flowing river by scouring the soil and the vegetation turf, cutting vegetation, applying waterborne plant litter, and after a period of recovery we measured vegetation responses. The experiment was repeated for two consecutive years.

    3. We found no significant effect of disturbance on species composition, but all three forms of disturbance significantly reduced species richness. There was no downstream variation in community responses to disturbance but morphological groups of species responded differently to different kinds of disturbance. Graminoids were most resistant, suppressed only by litter burial. All forms of disturbance except cutting reduced the density of herbaceous species, and species density of trees + shrubs and dwarf shrubs was negatively affected by both scouring and cutting. We also evaluated the effects of disturbance in relation to varying levels of species richness. In nearly all cases, responses were significantly negatively correlated with control plot species richness, and relative responses indicated that species-rich plots were less resistant to scouring and cutting.

    4. Our results suggest that although all disturbance treatments had an effect on species richness, variation in sensitivity to disturbance is not the most important factor shaping landscape-scale patterns of riparian plant species richness along rivers.

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    Renöfält&Nilsson_FWB2008
  • 15.
    Malm-Renöfält, Birgitta
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Spatial and temporal patterns of species richness in a riparian landscape2005In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 32, no 11, p. 2025-2037Article in journal (Refereed)
    Abstract [en]

    Aim: To test for control of vascular plant species richness in the riparian corridor by exploring three contrasting (although not mutually exclusive) hypotheses: (1) longitudinal patterns in riparian plant species richness are governed by local, river-related processes independent of the regional species richness, (2) riparian plant species richness is controlled by dispersal along the river (longitudinal control), and (3) the variation in riparian plant species richness mirrors variation in regional richness (lateral control).

    Location: The riparian zones of the free-flowing Vindel River and its surrounding river valley, northern Sweden.

    Methods: We used data from three surveys, undertaken at 10-year intervals, of riparian reaches (200-m stretches of riverbank) spanning the entire river. In addition, we surveyed species richness of vascular plants in the uplands adjacent to the river in 3.75-km2 large plots along the same regional gradient. We explored the relationship between riparian and upland flora, and various environmental variables. We also evaluated temporal variation in downstream patterns of the riparian flora.

    Results: Our results suggest that local species richness in boreal rivers is mainly a result of local, river-related processes and dispersal along the corridor. The strongest correlation between species richness and the environment was a negative one between species number and soil pH, but pH varied within a narrow range. We did not find evidence for a correlation between species richness on regional and local scales. We found that the local patterns of species richness for naturally occurring vascular plants were temporally variable, probably in response to large-scale disturbance caused by extreme floods. Most previous studies have found a unimodal pattern of species richness with peaks in the middle reaches of a river. In contrast, on two of three occasions corresponding to major flooding events, we found that the distribution of species richness of naturally occurring vascular plants resembled that of regional diversity: a monotonic decrease from headwater to coast. We also found high floristic similarity between the riparian corridor and the surrounding landscape.

    Main conclusions: These results suggest that local processes control patterns of riparian species richness, but that species composition is also highly dependent on the regional species pool. We argue that inter-annual variation in flood disturbance is probably the most important factor producing temporal variability of longitudinal species richness patterns.

  • 16.
    Nilsson, Christer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Linking flow Regime and water quality in rivers: a challenge to adaptive catchment management2008In: Ecology & Society, E-ISSN 1708-3087, Vol. 13, no 2, p. 18-Article in journal (Refereed)
    Abstract [en]

    Water quality describes the physicochemical characteristics of the water body. These vary naturally with the weather and with the spatiotemporal variation of the water flow, i.e., the flow regime. Worldwide, biota have adapted to the variation in these variables. River channels and their riparian zones contain a rich selection of adapted species and have been able to offer goods and services for sustaining human civilizations. Many human impacts on natural riverine environments have been destructive and present opportunities for rehabilitation. It is a big challenge to satisfy the needs of both humans and nature, without sacrificing one or the other. New ways of thinking, new policies, and institutional commitment are needed to make improvements, both in the ways water flow is modified in rivers by dam operations and direct extractions, and in the ways runoff from adjacent land is affected by land-use practices. Originally, prescribed flows were relatively static, but precepts have been developed to encompass variation, specifically on how water could be shared over the year to become most useful to ecosystems and humans. A key aspect is how allocations of water interact with physicochemical variation of water. An important applied question is how waste releases and discharge can be managed to reduce ecological and sanitary problems that might arise from inappropriate combinations of flow variation and physicochemical characteristics of water. We review knowledge in this field, provide examples on how the flow regime and the water quality can impact ecosystem processes, and conclude that most problems are associated with low-flow conditions. Given that reduced flows represent an escalating problem in an increasing number of rivers worldwide, managers are facing enormous challenges.

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    Nilsson&Renöfält_E&S2008
  • 17.
    Nilsson, Christer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Mygg och Bti i nedre Dalälven: Utvärdering av ett vetenskapligt uppföljningsprogram2009Report (Other academic)
    Abstract [en]

    This report presents the results of a review of the scientific follow-up studies of themosquito control programme in the lower river Dalälven. The report describes howthe questions in the follow-up programme have been answered and discusses therelevance of presented questions. It is concluded that the scientific follow-up workon eventual effects of the application of Bti has failed in sampling design andanalysis. The collected data do not provide the basis for the conclusions that havebeen drawn. The questions included in the follow-up programme have not beenanswered in a scientifically convincing manner. It is not considered meaningful tocontinue the follow-up work with its present restricted design, nor letting staffleading the large-scale mosquito control evaluate effects of its own activities. Instead,a wider research approach needs to be taken, oriented towards understandingnot only the various effects of Bti treatment but also the role of environmental factorsin regulating mosquito populations, the ecological role of mosquitoes, theirhistory in the region, and the effects of various mosquito densities. The internationalliterature is reviewed with an emphasis on health effects of Bti, ecological effectsof Bti, mosquito resistance to Bti and Bti persistence in the field. The literature doesnot provide support for the conclusion that Bti use is completely harmless. Thereport recommends a closer study of how the regulated river flow – a main cause ofthe mosquito abundance – can be modified to permanently reduce the number ofmosquitoes. Awaiting the realization of such a change a general mosquito controlwith Bti should be allowed, also in nature protected areas, and the state should takeon the responsibility for the actions. The ecosystem effects of such a control shouldbe followed closely, and the control should be modified should such unwantedeffects be revealed. The economic, social and medical consequences the extremelyhigh mosquito abundances can mean for local inhabitants should be studied moreclosely, for example inconveniences for agriculture, tourism and school. Furthermore,it needs to be considered whether the most common mosquito species in thearea, Aedes sticticus and A. vexans, should be viewed as natural ecosystem componentsworthy of protection, or as invasive species that need to be combated to preservemore original natural values. Nature authorities should also take the initiativeto execute a wide information campaign to increase the local knowledge level andto establish a locally rooted confidence for their activities. They have an importanttask in demonstrating how high natural values and human living can be combinedwithout humans experiencing nature as a nuisance.

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    Rapport6305
  • 18.
    Renöfält, Birgitta M
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Hydroecological patterns of change in riverine plant communities2007In: Hydroecology and ecohydrology: past, present and future / [ed] Paul J Wood, David M Hannah, JP Sadler, Chichester: Whiley , 2007Chapter in book (Other academic)
  • 19.
    Renöfält, Birgitta Malm
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Spatial patterns of plant invasiveness in a riparian corridor2005In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 20, no 2, p. 165-176Article in journal (Refereed)
    Abstract [en]

    Analysis of landscape-scale patterns of plant invasiveness can assist in interpreting spatial patterns of plant species richness. We investigated downstream variation in plant invasiveness in the riparian corridor of the free-flowing Vindel River in northern Sweden by introducing seeds of an alien species, Helianthus annuus, in 0.25 m2 plots of natural vegetation from mountain headwaters to the coast and found a significant downstream pattern with middle reaches having the highest invasiveness. We related invasiveness to species richness, both on a reach scale (200-m long stretches of riverbank encompassing the experimental plots) and on the scale of experimental plots. We found no significant correlation between plant invasiveness and species richness, neither at the reach nor at the plot scale. The number of available soil substrates shows a significant positive quadratic relationship with location along the river and substrate fineness shows a near significant negative quadratic relationship with location along the river, with middle reaches having coarser substrates. Several studies have shown that plant species richness in riparian corridors often exhibits a quadratic pattern with highest species richness in the middle reaches of a river, similar to the pattern we found for invasiveness. Although species richness per se might not be a primary factor for invasibility, the same habitat conditions as those supporting plant species richness, can help in explaining large-scale patterns of plant invasion in riparian zones.

  • 20.
    Renöfält, Birgitta
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Miljöanpassade flöden: sammanställning av forskning och utveckling med avseende på "flödesregimer"2006Report (Other academic)
  • 21.
    Widén, Åsa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ahonen, Jani
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Degerman, Erik
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ljungan inför miljöprövning av vattenkraften: naturvärden, flöden och strömhabitat samt möjliga miljönyttor2022Report (Other academic)
    Abstract [sv]

    Denna rapport utgör en beskrivning av dagens vattenkraftproduktion, återstående strömhabitat och nutida och dåtida naturvärden i Ljungan med förslag till miljöåtgärder och en skattning av kostnaderna (i form av kraftproduktion) och miljönyttorna (främst räknat som tillgängliggjort habitat). I arbetet, som följer de riktlinjer som presenteras i rapporter från forskningsprojektet Priokliv, ingår även en bristanalys där dagens situation jämförs med förhållanden innan vattenkraften byggdes ut. Därefter har vi utformat förslag på miljöanpassade flöden, öppnade vandringsvägar samt kompletterande åtgärder. Miljöåtgärderna fokuserar främst på ett antal scenarier med olika åtgärder där kostnader och miljönyttor jämförs med dagens situation. Arbetet fokuserar på huvudfårorna av Ljungan och Gimån i de vattenkraftpåverkade delarna. Vattensystemet har delats in i 20 dämningsområden, sträckor mellan kraftverk, där naturvärdet beskrivs utifrån habitat (strömsträckor, deltaområden, tillgång till biflöden, skyddad natur och kulturmiljöer) och förekommande arter. För de senare ligger fokus på arter som är rödlistade eller pekas ut i Art- och Habitatdirektivet eller Fågeldirektivet. Artuppgifterna kommer från standardiserad övervakning (fisk, flodpärlmussla) redovisad i offentliga databaser samt från rapporterade artförekomster till SLU:s Artportal. Analyserna visar att en stor påverkan skett av vattensystemet med förändrat flödesmönster, omfattande korttidsreglering och 18 torrfåror i området med en samlad areal av 219 hektar. Ett normalår är det nolltappning vid 175 tillfällen nedströms Flåsjön och 286 tillfällen nedom Holmsjön. Påverkan från korttidsreglering i älvsystemet är således omfattande, och åtgärder som kan lindra dess effekter har stor potential. Fiskfaunan har påverkats och laxens område utgör idag endast 7% av den forna längden. Endast 3% av avrinningsområdets dammar har fiskvägar. Sammanställningen visar samtidigt att det finns naturvärden kvar. Vid jämförelse med fallhöjd före regleringen av Ljungan med nuvarande förhållande visar analyserna att 16% av fallhöjden återstår. Beskrivningen av naturvärden visar att de är klart högst i de övre delarna av Ljungan och Gimån, dvs ovanför området där vattenkraftproduktion sker, men ett antal ekologiska värdekärnor har identifierats i de nedre delarna. Vi har även beaktat effekterna av det framtida klimatet. För år 2040 beräknas produktionen av elektricitet öka med i medel 3,1% jämfört med nuvarande förhållanden för hela avrinningsområdet. Vi förordar mer dynamiska modeller för att beskriva miljönyttorna som omfattar påverkan på processer i vattendraget, gynnad areal av bristhabitat, tillgängliggjord areal genom konnektivitet samt biologi som är kopplat till hydrologi på varierande skala gällande tidsupplösning och geografi. Nyttorna beskrivs genom tillgänglig gjord eller förbättrad areal av strömmande habitat, minskad påverkan av korttidsregleringseffekter, konnektivitet i form av tillgängliggjort habitat och vattendragslängd i denna rapport. Ekologisk reglering har modellerats med 13 scenarios och resultaten varierar gällande produktionspåverkan från att produktionen ökar med 1,2% (nolltappningsförbud nedströms Holmsjön i framtida klimat 2040) till en minskning av produktionen med 15,2% (statiska spill till torrfåror motsvarande medellågvattenföring (MLQ)).  Samtliga scenarios med ekologisk reglering har påverkan på när produktionen av elektricitet sker över året, månad, vecka, dygn och timme. Det innebär att vi i modellerna flyttar produktionstillfället från tider med stora behov från samhället av elektricitet till tillfällen med lägre behov från samhället. Resultaten presenteras samlat mer utförligt i kapitel 8-9.  Vi belyser betydelsen av noggranna och detaljerade beskrivningar av åtgärder, kostnader, miljönyttor och produktionspåverkan på energisystemet med avrinnesområdet som den minsta geografiska ytan.

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  • 22.
    Widén, Åsa
    et al.
    Sveriges lantbruksuniversitet, Umeå, Sverige.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ahonen, Jani
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Lagan inför miljöprövning av vattenkraften2023Report (Other (popular science, discussion, etc.))
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    fulltext
  • 23.
    Widén, Åsa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Degerman, Erik
    Swedish University of Agricultural Sciences, Institute of Freshwater Research, Drottningholm, Sweden.
    Wisaeus, Dag
    AFRY, Stockholm, Sweden.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Environmental Flow Scenarios for a Regulated River System: Projecting Catchment-Wide Ecosystem Benefits and Consequences for Hydroelectric Production2022In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 58, no 1, article id e2021WR030297Article in journal (Refereed)
    Abstract [en]

    To enable prioritization among measures for ecological restoration, knowing the expected benefits and consequences of implementation is imperative but rarely explicitly quantified. We developed a novel method to prioritize among environmental flow measures to rehabilitate ecosystems in the Ume River catchment in northern Sweden, a river system heavily regulated for hydropower production. Our strategy was to identify measures with minimal impact on hydropower production while providing substantial environmental benefits. Based on field surveys of remaining natural values and potential for ecological rehabilitation, we quantified the projected gain in habitat area of implementing environmental flows for target organism groups, for example, lotic fish species and riparian vegetation, along the whole river length. We quantified the consequences for hydropower production by identifying a set of hydropower operational rules reflecting the constraints added by environmental flows. We then used production optimization software to calculate changes in hydropower production and revenues. Implementing restrictions on zero-flow events by mandating minimum discharge at all run-of-river hydropower stations and allocating 1%–12% of mean annual discharge to bypassed reaches in the entire catchment would result in a 2.1% loss of annual electricity production. Adding flow to fishways would increase the loss to 3.1% per year. With implementation of more natural water-level fluctuations in run-of-river impoundments, the loss increases to 3.8%. These actions would increase the habitat for lotic species like the grayling Thymallus more than threefold and increase the area of riparian vegetation by about 66%. Our method forms a basis for ongoing implementation of nationwide environmental rehabilitation schemes.

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  • 24.
    Widén, Åsa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Degerman, Erik
    Institute of Freshwater Research, Department of Aquatic Resources, Swedish University of Agricultural Sciences, Drottningholm, Sweden.
    Wisaeus, Dag
    AFRY, Frösundaleden 2, Stockholm, Sweden.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Let it flow: Modeling ecological benefits and hydropower production impacts of banning zero-flow events in a large regulated river system2021In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 783, article id 147010Article in journal (Refereed)
    Abstract [en]

    Hydropeaking, defined as rapid and frequent changes in flow to optimize hydropower production, is an increasingly common procedure negatively affecting lotic habitats in riverine ecosystems. An important aspect of hydropeaking is zero-flow events, occurring when hydropower stations are stopped due to low energy demand or low electricity prices. We quantified the ecological benefits and consequences for hydropower production of restricting zero-flow events. The 19 major hydropower stations in the Ume River system in northern Sweden stand still with no discharge 9% to 55% of the time a hydrologically normal year, transforming lotic habitat to stagnant water. The duration of zero-flow events is exacerbated in dry years, with no discharge for 28% of the time in a typical station, to be compared with 7% in a wet year. Zero-flow events affect the behavior of fish, altering the fish community, and potentially result in low oxygen levels and low food supply to filter-feeding macroinvertebrates. We modelled the consequences of restricting zero-flow events by introducing minimum flows equaling mean annual low flow or higher for the entire Ume River catchment. The measure would result in an additional 240 ha of shallow lotic habitat with gravel to boulder streambeds having flow velocity exceeding 0.1 m/s, i.e. suitable for lotic species such as grayling Thymallus thymallus. In addition, the measure would enable creating another 107 ha of similar habitat after structural rehabilitation of river reaches. All measures would result in a mean loss of hydropower production of 0.5% per year for the entire river system, 98% of which would occur between May and October when the demand for electricity is lower. Hydropower production would also be partly moved from daytime to nighttime. As zero-flow events are common in several other river systems, restrictions on their frequency and duration could be implemented in many areas.

  • 25.
    Widén, Åsa
    et al.
    Statens Lantbruksuniversitet.
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Restaurering av Juktån2023Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    Restaurering av Juktån är ett samverkansprojekt som har drivits på frivillig basis av den ideella föreningen Samverkan Umeälven (www.umealven.se) tillsammans med Umeälvensvattenregleringsföretag, Vattenfall och Umeå Universitet. Juktån är en 60 kilometer lång torrfåra med minimitappning om 12% av det oreglerade flödet (MQ) vid reglerings. I produktionssystemet har den en funktion som spillfåra. Projektets ambition och mål var att Juktån skulle återfå ekologisk funktion med fungerande reproduktion av öring och harr, mer naturlig och bredare strandvegetation och svämskogar, mer naturlig artsammansättning av makrofyter samt en sedimentationsprocess med mindre deponering av silt och finsediment. Juktånprojektet har kartlagt och genomfört biotopåtgärder samt restaurerat huvudfåran sträckan nedströms Tjangarn och sidofåran Lickotgrenen under 2019 och 2020. Totalt har dryga 35 kilometer torrfåra restaurerats, hundratals trösklar och flottledsobjekt har rivits ut. Juktåprojektet ansökte hos Mark och Miljö Domstolen (MMD) om att ändra den relativt statiska minimitappningen till en säsongsanpassad minimitappning, vilket beviljades i augusti 2020 och infördes våren 2021. Metoderna för att genomföra restaureringen bygger på restaureringsekologi och sambandet till naturlig flödesregim. Juktåns restaurering har inneburit en komplex restaurering från utrivning av grunddammar och trösklar, restaurering av den fysiska miljön för att gynna öring, harr, makrofyter, strandvegetation och processer. Vi har utgått från ekologi i oreglerade vattendrag och utvecklat metoder speciellt anpassat för torrfåror med minimitappning. Preliminära resultat visar på en ökad reproduktion av öring, mer naturliga processer kopplat till flöde, sedimentation, vattenhastighet och som har påverkat både makrofyter samt strandvegetation.

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    Restaurering av Juktån
  • 26.
    Widén, Åsa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Segersten, Joel
    Donadi, Serena
    Degerman, Erik
    Malm-Renöfält, Birgitta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson Tiselius, Andreas
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Lundbäck, Sofi
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Sveriges torrfåror: geografi, naturvärden och metoder för miljöförbättringar2022Report (Other academic)
    Abstract [en]

    The aim of the project was to develop methods to facilitate decisions on minimum flow release and other environmental measures in bypassed river sections, that is, river sections where discharge has been diverted to hydropower stations. Sometimes, discharge is also diverted from one river to another to increase hydropower production. This leaves the original river channel dry or with reduced discharge. Many of these reaches were originally rapids, and ecosystems and species associated with them have become rare.  

    We aimed to map all bypassed river reaches in Sweden, and identified 972 ones in a database. The majority of these lack any mandates on minimum flow release. Out of 622 reaches with flow data, 481 lacked mandated minimum flow release. The 137 bypassed reaches with minimum flows had an annual flow averaging being only 3.6% of their pristine mean annual discharge.  

    The bypassed reaches had a lower proportion of rheophilic fishes and lower fish abundance compared to reference sites in free-flowing rivers, according to electrofishing data. Bypassed reaches with minimum flow release had fish communities with higher proportion of rheophilic species, higher abundance of fish, and more fish species per site compared to bypassed reaches with no minimum flow release. Furthermore, the proportion of rheophilic over lentic fish species, fish abundance as well as species richness of fish increased with increasing magnitude of minimum flow release, with diminishing returns at higher flow levels.  

    The mean slope of the channels of the bypassed reaches was relatively high (3.6%), and they generally correspond to runs and rapids in terms of flow velocity. The average length of bypassed reaches was 1317 m, with median lengths being 319 m, the distribution being skewed with many short and fewer long ones. The majority of them were positioned in the lower reaches of catchments, in stream order 1 and 2 counting from the mouth. Many bypassed reaches were part of larger waterbodies as defined by the EU Water Framework Directive. Among the 570 where the bypassed reach constituted a waterbody, 140 had been classified as heavily modified.  

    A functional collaboration process among stakeholders (including hydropower managers, authorities, consultants and NGOs) is key to be able to select which bypassed reaches to be targets of ecological rehabilitation, and to implement rehabilitation measures. We present a framework to facilitate the process, and discuss the competences needed for a successful process. We also present a methodology to enable a structured work flow going from mapping bypassed reaches, to analyses of impacts and needs and potential for ecological rehabilitation. When summing the natural values this gives an idea of both rehabilitation needs and what is practical to implement given ecosystem functions and services.  

    As a basis for making decisions on the magnitude of minimum flow release, we present a list of ecosystem states or functions, and the aspect of the flow regime needed to maintain them. This can help determining the flow needed to obtain specific ecosystem functions or states, or conversely, given flow, what ecosystem functions and states are realistic to obtain. We also present a methodology for making surveys of bypassed reaches, taking quantitative randomized samples of important variables. The survey enables quantitative evaluations of rehabilitation outcomes. 

    We argue that environmental court decisions on bypassed sections need to be formulated so they are relevant also in the face of climate change and changes in the electrical production system. This can be setting flow targets as proportions of the total discharge rather than in absolute numbers, and linking changes in discharge to changes in local run-off rather than setting fixed dates. 

    To conclude, we found that although most bypassed river reaches lack mandated minimum flow release and have not been targets of structural rehabilitation efforts, such actions are deemed effective in improving ecological conditions, calling for implementation of such rehabilitation efforts.

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