| 1. |
- Hoppenreijs, Jacqueline, et al.
(author)
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Three major steps toward the conservation of freshwater and riparian biodiversity
- 2024
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In: Conservation Biology. - : John Wiley & Sons. - 0888-8892 .- 1523-1739. ; 38:3
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Journal article (peer-reviewed)abstract
- 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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| 2. |
- Jansson, Roland, et al.
(author)
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Restaurering av sjöar ochvattendrag i ett framtida klimat
- 2020
-
Reports (other academic/artistic)abstract
- Sveriges klimat befinner sig i en trend av ökande temperatur och förändrad nederbörd, vilket påverkar sjöar och vattendrag. Denna rapport redovisar slutsatser av ett projekt som analyserat hur ekologisk restaurering och rehabilitering av sötvattensekosystem påverkas av klimatförändringar: Vi har utvärderat olika metoders relevans för att lindra effekterna av eller anpassa ekosystemen till ett förändrat klimat, hur mål ska sättas och resultat utvärderas, samt analyserat tillgängliga alternativ för att förvalta biologisk mångfald och ekosystemfunktioner i ett nytt klimat.Vattendrag och sjöar är dynamiska system som påverkas av och anpassar sig efter processer i avrinningsområdet. De är både känsliga för förändringar men har också förmågan att anpassa sig snabbt till nya förhållanden. En konsekvens av detta är att sötvattensekosystem kommer att förändras om klimatet förändras. De flesta av metoderna för att återskapa naturliga processer i vattendrag och sjöar gör dem också mer resilienta med mindre behov av återkommande interventioner, och ökar deras kapacitet att återhämta sig från störningar, vare sig de är resultatet av klimatförändringar eller andra drivkrafter. Restaurering kan därför användas för att göra att ekosystem återhämtar sig bättre eller är mer motståndskraftiga mot störningar, inklusive sådana som skapas eller blir vanligare till följd av klimatförändringar.Det är stor skillnad på restaurering av ekosystem efter avslutad verksamhet och rehabilitering av ekosystemfunktioner i sjöar och vattendrag där exploateringen som skapat miljöproblemen fortgår. I första fallet är målet oftast återskapande av ett oförstört tillstånd. Här lägger klimatförändringar hinder i vägen då en återgång till ett historiskt tillstånd inte längre är möjligt. Om det finns pågående verksamhet att ta hänsyn till måste kompromisser med den pågående verksamheten till, och dessa kan ha större påverkan på restaureringsprojektet än klimatförändringarna.Många metoder för att restaurera sjöar och vattendrag har föreslagits kunna spela en roll i att lindra effekterna av klimatförändringar, eller att hjälpa ekosystem och samhällen att anpassa sig till ett förändrat klimat. Ett gemensamt tema för sådana åtgärder är att de inte är specifika svar på klimatförändringar men bringar ekosystemen närmare ett historiskt referenstillstånd genom att återinföra naturliga processer eller återintroducera försvunna strukturer. Det viktigaste är att välja åtgärder som bidrar till att återupprätta naturliga processer och som ökar populationsstorlekarna av naturligt förekommande arter. Vi går igenom olika åtgärder för att göra vattenflöden mer naturliga, öka konnektiviteten mellan olika landskapskomponenter, och möjliggöra för arter att etablera sig.Eftersom klimatet kommer att förändras de närmaste hundra åren oavsett vilket klimatscenario som blir verklighet, måste varje restaureringsprojekt ta i beaktande att miljöförhållandena inte kan antas vara stationära. I samband med genomförande av restaureringsåtgärder bör därför det ingå en riskanalys i projekten – vad kan gå fel och hur ska det undvikas? Med nya klimatförhållanden som påverkar både artsammansättning och ekologiska processer måste projektledningen tänka annorlunda runt hur de sätter mål för ekologisk restaurering, vilka referensförhållanden som används för att jämföra de restaurerade ekosystemen med, och hur metoder för att studera ekosystemens återhämtning efter genomförd åtgärd. Ett rimligt sätt att identifiera referenstillstånd vid ekologisk restaurering i ett förändrat klimat är att antingen utnyttja opåverkade system eller historisk information som utgångspunkt för att identifiera referensförhållanden, och sedan använda sig av modeller och prognosverktyg för att förutsäga hur dessa system kommer att förändras.Arbete med uppföljning och utvärdering av restaureringsinsatser måste ta hänsyn till ökad osäkerhet om i vilken riktning ekosystem utvecklas, vilket kräver nya strategier och metoder. Vi föreslår ett antal förändringar av hur man ser på uppföljning av ekosystem efter restaureringsinsatser: (1) Ekosystemens utveckling eller återhämtning efter genomförda åtgärder borde ses som en korridor snarare än en enskild stig eller bana. (2) Innebörden i och vilken tid det förväntas ta att uppnå olika mål bör baseras på scenarier för framtida klimat. (3) Det bör göras analyser av potentiella risker och kritiska faser i återhämtningsprocessen, för att öka chansen att förutse när ekosystem förändras från ett tillstånd till ett annat och undvika extrema klimathändelser. (4) Utvärderingar av resultaten av restaureringsinsatser bör göras flera gånger, för att kunna justera åtgärder och mål i respons på en föränderlig verklighet. I ekologiska restaureringsprojekt är det viktigt att besluta om en konkret målbild för projektet, men projekten måste acceptera och omfamna osäkerheterna i vilka ekologiska tillstånd som kan bli verklighet i framtiden. Restaurerings- och rehabiliteringsprojektens mål bör formuleras som ett spann av förhållanden snarare än ett specifikt tillstånd.Vi har analyserat hur olika ekoflödesalternativ påverkar vattenkraftsproduktionen i ett framtida klimat genom att använda scenarier för framtida flöden i Umeälvens avrinningsområde och simulera vilken effekt olika ekoflödesalternativ skulle få för elproduktionen. Sammanfattningsvis visar analyserna vi presenterat att ekoflöden kan införas i Umeälven utan att vattenhushållningen riskeras i ett framtida klimat: Eftersom vattenflödena förväntas öka något i avrinningsområdet i framtiden finns det potential att antingen öka vattenkraftsproduktionen eller att ekoflöden kan införas och upprätthållas med mindre kostnad jämfört med dagens situation. Situationen kan dock bli mer ansträngd under hydrologiskt torra år, då vattenkraftsproduktionen normalt är lägre.En annan fråga vi berör hur man prioriterar vilka områden som ska restaureras. Om prioritering av lokaler i behov av restaurering görs utifrån målet att bevara befintliga naturvärden och hotade arter, innebär hänsyn till klimatförändringar att göra en analys av hur ett förändrat klimat påverkar möjligheterna att uppnå gynnsam bevarandestatus genom restaurering. Om prioritering görs utifrån att identifiera de områden där restaurering kan ge den största förändringen i statusklass eller naturvärden, blir huvudfokus istället att beräkna hur stora de förväntade miljönyttorna kommer att bli i framtiden, givet förväntade effekter av klimatförändring på arter och ekosystem.Integrering av klimatförändringsperspektivet i restaureringsarbete är sällsynt, men de projekt som gjort det pekar på vikten av att ta in klimatperspektivet redan på planeringsstadiet, att jobba på avrinningsområdesnivå, och att inkludera ett brett spektrum av intressegrupper i projektet som nycklar till framgång.Klimatförändringsperspektivet behöver till fullo inkluderas i skötsel och styrning av restaureringsprojekt. Detta kräver adaptiva och långsiktiga program för restaurering och uppföljning av sötvattensmiljöer. Dessa bör utgå från bästa tillgängliga data på klimatförändringseffekter för att kunna minska osäkerheten och oförutsägbarheten i klimatförändringseffekter på vattendragsekosystemen. Om inte detta görs kan restaureringsåtgärdernas resultat i framtiden inte bara bli verkningslösa, utan i värsta fall till och med kontraproduktiva.
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| 3. |
- Kuglerova, Lenka, et al.
(author)
-
Groundwater discharge creates hotspots of riparian plant species richness in a boreal forest stream network
- 2014
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In: Ecology. - : Ecological Society of America. - 0012-9658 .- 1939-9170. ; 95:3, s. 715-725
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Journal article (peer-reviewed)abstract
- 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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| 4. |
- Kuglerová, Lenka, 1985-
(author)
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Grow with the flow : Hydrological controls of riparian vegetation in boreal stream networks
- 2015
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Doctoral thesis (other academic/artistic)abstract
- What drives species diversity across landscapes is one of the most fundamental questions in ecology. Further, understanding the mechanisms underlying species diversity patterns is important not only for forming and challenging ecological theories but also essential for appropriate landscape management and effective nature conservation. This thesis focuses on patterns of vascular plant, moss and liverwort species richness and composition in relation to water flow in boreal-forest catchments, focusing mostly on riparian zones (RZs), that is terrestrial areas bordering streams and rivers. I addressed some of the most essential questions related to the ecology of riparian vegetation including the role of stream network position, groundwater (GW) flow paths, substrate availability, upland perturbations, and stream restoration. I also investigated how riparian soil processes and habitat properties relate to these factors in order to provide a holistic understanding of riparian dynamics. The results showed that the species richness and composition of riparian vascular plants, mosses and liverworts are strongly influenced by position along the stream network, GW discharge, presence of variable substrates in RZs, and by stream restoration. Generally, more species were found downstream in the network, at sites with inputs of upland GW, sites with high diversity of substrates (e.g., open mineral soil, rocks, stones, wood and bark), and along streams restored after channelization. This thesis also describes how riparian habitat properties responded to position in the landscape and human impacts, thus providing mechanistic links between plant species diversity and riparian processes across spatial scales. These ecological insights are further implemented into numerous recommendations for freshwater and upland management in boreal Sweden. Given that streams and rivers connect landscape elements both longitudinally and laterally I argue that management plans should be designed for entire catchments instead of individual river segments. Ignoring the connectivity of streams as well as the high connectivity of riparian areas to uplands via GW flows may result in failure of restoration, mitigation and/or protection actions. Further, during forestry operations more emphasis should be placed on GW discharge areas along streams and rivers, because they represent important ecological and biogeochemical hotspots in the landscape. The riparian buffers left along streams in boreal catchments affected by forestry are presently insufficiently wide and often uniform in width. This threatens the assemblages of species in GW discharge hotspots and the ecosystem services they provide. Overall, this thesis describes a holistic picture of riparian diversity patterns and riparian processes in boreal landscapes, acknowledges and elaborates on current ecological theories, presenting new patterns in biodiversity, and offers management guidelines.
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| 5. |
- Kuglerová, Lenka, 1985-, et al.
(author)
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Local and regional processes determine plant species richness in a river-network metacommunity
- 2015
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In: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 96:2, s. 381-391
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Journal article (peer-reviewed)abstract
- 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.
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| 6. |
- Lejon, Anna, 1979-, et al.
(author)
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Dam removal effects on riparian vegetation
-
Other publication (other academic/artistic)abstract
- 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.
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| 7. |
- Lejon, Anna G.C. 1979-, et al.
(author)
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Conflicts associated with dam removal in Sweden
- 2009
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In: Ecology and Society. - Wolfville : The Resilience Alliance. - 1708-3087. ; 14:2, s. 4-
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Journal article (peer-reviewed)abstract
- 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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| 8. |
- Lejon, Anna G.C. 1979-
(author)
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Ecosystem response to dam removal
- 2012
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Doctoral thesis (other academic/artistic)abstract
- This thesis aims to improve our understanding of how riverine ecosystems respond to dam removal. Riverine and particularly riparian ecosystems are among the most variable and important features of all landscapes. They connect landscape elements both longitudinally and laterally, and are governed by processes such as flooding, erosion and deposition that create dynamic, diverse and heterogeneous habitats. In fact, riparian zones are among the world’s most species-rich habitats. Worldwide there are millions of dams that fragment stream and river systems, regulate flows and degrade ecosystems. Dams impact freshwater, marine and terrestrial ecosystems and threaten biodiversity by disrupting organism movements and energy flows in the landscape. An important upstream effect of dams is inundation of habitats and development of new shorelines around impounded areas. Effects downstream of dams are mainly caused by changed hydrological regimes and retention of organic and inorganic materials in reservoirs, leading to reduced transport and dispersal of for example seeds to reaches downstream. The removal of dams create expectations that biota will eventually recover. We have studied a number of dam removal projects in Sweden. Our experimental results showed that following dam removal, newly exposed soils in former impoundments were rapidly colonized by pre-removal species. Their species richness increased slightly with time and their species composition indicated a slow change towards that in the reference site. In addition, the vegetation in formerly impounded areas showed a direction of change from lentic riparian plants (high proportion of aquatics) towards lotic ones, consisting of native perennials typical of free-flowing streams. We also found that the apprehensions that former impoundments would turn into pools of mud did not come true; in fact, a process towards more pristine channel morphology was observed. After removal there was erosion and downstream transport of sediment. We found only minor effects on macroinvertebrate communities. For example, a few species decreased over the years, suggesting that dam removal in itself might cause a temporary disturbance. This highlights the importance of long-term studies after dam removal, and also the importance of comparisons with pre-removal conditions and stretches unaffected by dams. Thorough documentation of executed dam removal projects and distribution of the results and experiences are tremendously important in the planning process of future decommissioning projects. Also, our experiences have taught us that in order to attain a successful dam removal it is important to involve stakeholders such as non-governmental organizations and local inhabitants in the process.
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| 9. |
- Lejon, Anna, 1979-, et al.
(author)
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Succession of riparian plants following dam removal in a boreal stream in central Sweden
-
Other publication (other academic/artistic)abstract
- 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.
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| 10. |
- Malm-Renöfält, Birgitta, et al.
(author)
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Connecting variation in vegetation and stream flow : the role of geomorphic context in vegetation response to large floods along boreal rivers
- 2007
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In: Journal of Applied Ecology. - Oxford : Blackwell (for the British ecological society). - 0021-8901 .- 1365-2664. ; 44:1, s. 147-157
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Journal article (peer-reviewed)abstract
- 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.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.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.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.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.
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