The Effect of Glines Canyon Dam on Hydrochorous Seed Dispersal in the Elwha River

Chenoweth, Joshua

doi:10.3955/0029-344x-82.s.i.197

Cited by 38 publications

(54 citation statements)

References 57 publications

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“…Understanding the factors that control species richness, colonization, extinction, turnover, and species composition along rivers is important as most of the world's rivers are developed and heavily managed by humans . The rate of extinction in freshwater ecosystems is high and increasing, and riverine and aquatic ecosystems are becoming simplified through homogenization of physical processes (Poff et al 2007) and fragmented by impoundments Wohl 2006, Brown andChenoweth 2008). Further, given that plant species richness is related to other important ecosystem processes such as productivity, resistance to invasion, habitat and resource heterogeneity, and ecosystem functioning, sustaining the processes that maintain plant species richness has important ecological as well as sociological and economic implications.…”

Section: Discussionmentioning

confidence: 99%

“…This result supports earlier studies suggesting that although the Ume River catchment contains a similar number of species in its overall species pool (256 species) to the Vindel River (247 species), dams and reservoirs along its course significantly repress the potential species richness of riparian plant communities (Nilsson et al 1991a, Jansson et al 2000b. Dams, such as those along the Ume River, are efficient at trapping seeds, obstructing long-distance dispersal, and causing the pool of potential species to be reset at each impoundment Wohl 2006, Brown andChenoweth 2008).…”

Section: Species Richness Between Free-flowing and Regulated Riversmentioning

confidence: 99%

“…Dams are also barriers to the movement of propagules along river corridors, trapping 75-95% of propagules and reducing the propagule species diversity in rivers along reaches downstream of dams (Andersson et al 2000b, Jansson et al 2005. Dams obstruct dispersal of seeds from regional seed sources upstream, which may reduce potential richness of downstream plant communities Wohl 2006, Brown andChenoweth 2008). Jansson et al (2000b) concluded that plant communities within impoundments were isolated (and compositionally distinct) from plant communities in impoundments upstream and downstream.…”

Section: Introductionmentioning

confidence: 99%

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Consequences of propagule dispersal and river fragmentation for riparian plant community diversity and turnover

Merritt

Nilsson

Jansson

2010

Ecological Monographs

103

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Consequences of propagule dispersal and river fragmentation for riparian plant community diversity and turnover. Abstract. The spatial distribution and temporal availability of propagules fundamentally constrain plant community development. This study experimentally tested several hypotheses about the relative roles of wind and water dispersal in colonization and development of riparian communities along rivers. Through controlling the source of propagules (dispersed by wind, water, or both) reaching newly created, bare river margin sites, we isolated the relative roles of dispersal and other factors in plant community development over five years. Replicated treatments were established at 12 sites spanning 400 km along two adjacent rivers in northern Sweden, one fragmented by a series of dams, the other free-flowing. Bare river margins receiving only water-dispersed propagules had significantly higher species richness compared to plots receiving only wind-dispersed propagules during the initial two years of colonization. Species richness increased annually throughout the study along tranquil and turbulent reaches of the free-flowing river but reached an asymptote at comparatively low richness after a single year on the impounded river. Propagule source strongly influenced species richness during the initial establishment along both rivers, with richness being significantly higher in plots receiving water-dispersed seeds. This strong treatment effect continued to be important through time along the regulated river but diminished in importance along the free-flowing river where other factors such as soil moisture, light availability, and exposure of sites to fluvial disturbance overshadowed the influence of dispersal pathway in mediating species richness. This suggests that hydrochory (plant dispersal by water) may be more important for maintenance of diversity in regulated systems where long-distance dispersal is absent or negligible, but that the rich local propagule source along free-flowing rivers supports high species richness. The number of unique species was higher in water-dispersal plots along both the regulated and free-flowing rivers. This result suggests that hydrochory may contribute to temporal variability of sites, may enhance richness over time, and may have an important role in meta-population and meta-community dynamics of plant communities through long-distance (and local) dispersal and chance colonization. Our findings provide experimental evidence that water dispersal of plant propagules influences colonization dynamics and is important for long-term community development in riparian zones.

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Section: Discussionmentioning

confidence: 99%

Section: Species Richness Between Free-flowing and Regulated Riversmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Consequences of propagule dispersal and river fragmentation for riparian plant community diversity and turnover

Merritt

Nilsson

Jansson

2010

Ecological Monographs

103

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“…Given that turbulent reaches can be situated quite far apart, and the chances for a floating plant propagule to be dispersed from an upstream turbulent reach to a restored turbulent reach further downstream-and be deposited there-are rather small simply due to distance. For example, lakes are common in these systems and lakes-as well as other tranquil, wide water bodies-are efficient seed traps (Brown and Chenoweth 2008). When a plant propagule is finally stranded at a restored site, factors such as water levels, soil moisture and temperature need to be favorable to promote establishment (Merritt and others 2010), and such conditions are not likely to occur every year (Balke and others 2014).…”

Section: The Lack Of Biotic Response and Its Potential Causesmentioning

confidence: 99%

How Do Biota Respond to Additional Physical Restoration of Restored Streams?

et al. 2016

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Restoration of channelized streams by returning coarse sediment from stream edges to the wetted channel has become a common practice in Sweden. Yet, restoration activities do not always result in the return of desired biota. This study evaluated a restoration project in the Vindel River in northern Sweden in which practitioners further increased channel complexity of previously restored stream reaches by placing very large boulders (>1 m), trees (>8 m), and salmonid spawning gravel from adjacent upland areas into the channels. One reach restored with basic methods and another with enhanced methods were selected in each of ten different tributaries to the main channel. Geomorphic and hydraulic complexity was enhanced but the chemical composition of riparian soils and the communities of riparian plants and fish did not exhibit any clear responses to the enhanced restoration measures during the first 5 years compared to reaches restored with basic restoration methods. The variation in the collected data was among streams instead of between types of restored reaches. We conclude that restoration is a disturbance in itself, that immigration potential varies across landscapes, and that biotic recovery processes in boreal river systems are slow. We suggest that enhanced restoration has to apply a catchment-scale approach accounting for connectivity and availability of source populations, and that low-intensity monitoring has to be performed over several decades to evaluate restoration outcomes.

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“…Dam removal also restores natural hydrologic conditions (flow, temperature) and other critical habitat forming processes (large wood transport). Additionally, two reservoirs will be drained and exposed sediments on the reservoir bottom will be revegetated through natural processes (Brown and Chenoweth 2008) as well as supplemental revegetation (Chenoweth et al in press). Sedimentation due to dam removal and subsequent habitat degradation, the restoration of natural watershed processes, habitat expansion, and increases in nutrient availability focus the Elwha River ecosystem recovery monitoring efforts on four areas: (1) habitat and food web response to the release of stored sediment in the middle and lower Elwha; (2) food web response to salmon recolonization in the middle and upper Elwha; (3) the recovery of reservoir reaches as forests recolonize exposed reservoir sediments; and (4) responses of the river delta and nearshore ecosystem to release of stored sediment.…”

Section: Evaluating Physical and Biological Ecosystem Responsesmentioning

confidence: 99%