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Publications (10 of 15) Show all publications
Su, X., Polvi, L. E., Lind, L., Pilotto, F. & Nilsson, C. (2019). Importance of landscape context for post-restoration recovery of riparian vegetation. Freshwater Biology, 64(5), 1015-1028
Open this publication in new window or tab >>Importance of landscape context for post-restoration recovery of riparian vegetation
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2019 (English)In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 64, no 5, p. 1015-1028Article in journal (Refereed) Published
Abstract [en]

We tested whether the recovery of riparian vegetation along rapids that have been restored after channelisation for timber floating can be predicted based on floristic and geomorphic characteristics of surrounding landscape units. Our study was located along tributary stream networks, naturally fragmented in rapids, slow-flowing reaches, and lakes (i.e. process domains), in the Vindel River catchment in northern Sweden.

We tested whether landscape characteristics, specifically to what extent the geomorphology (affecting local abiotic conditions), species richness, and species composition (representing the species pool for recolonisation), as well as the proximity to various upstream process domains (determining the dispersal potential), can predict post-restoration recovery of riparian vegetation.

Our results indicate that post-restoration recovery of riparian vegetation richness or composition is not strongly related to landscape-scale species pools in these streams. The restored rapids were most similar to upstream rapids, geomorphically and floristically, including plant traits. Species richness of adjacent landscape units (upstream process domains or lateral upland zone) did not correlate with that of restored rapids, and proximity of upstream rapids or other process domains was only weakly influential, thus diminishing support for the hypothesis that hydrochory or other means of propagule dispersal plays a strong role in riparian vegetation community organisation after restoration in this fragmented stream network.

We conclude that, in these naturally fragmented stream systems with three discrete process domains (rapids, slow-flowing reaches and lakes), hydrochory is probably not the main predictor for short-term riparian vegetation recovery. Therefore, other factors than landscape context can serve in prioritising restoration and, in these systems, local factors are likely to outweigh landscape connectivity in the recovery of riparian vegetation.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
hydrochory, plant dispersal, riparian zone, species pool, streams
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-159391 (URN)10.1111/fwb.13282 (DOI)000466805700016 ()
Available from: 2019-06-10 Created: 2019-06-10 Last updated: 2019-06-10Bibliographically approved
Su, X., Lind, L., Polvi, L. E. & Nilsson, C. (2019). Variation in hydrochory among lakes and streams: effects of channel planform, roughness, and currents. Ecohydrology, 12(5), Article ID e2091.
Open this publication in new window or tab >>Variation in hydrochory among lakes and streams: effects of channel planform, roughness, and currents
2019 (English)In: Ecohydrology, ISSN 1936-0584, E-ISSN 1936-0592, Vol. 12, no 5, article id e2091Article in journal (Refereed) Published
Abstract [en]

The configuration of channels in stream networks is vital for their connectivity, biodiversity, and metacommunity dynamics. We compared the capacity of three process domains-lakes, slow-flowing reaches, and rapids-to disperse and retain plant propagules by releasing small wooden cubes as propagule mimics during the spring flood and recording their final locations. We also measured the geomorphic characteristics (planform, longitudinal profile, cross-sectional morphology, and wood) of each process domain. The three process domains all differed in morphology and hydraulics, and those characteristics were important in shaping the transport capacity of mimics. On average, lakes retained more mimics than slow-flowing reaches but did not differ from the retainment of rapids. Living macrophytes were the most efficient element trapping mimics. In rapids and slow-flowing reaches, most trapped mimics remained floating, whereas in lakes, most mimics ended up on the banks. The decay curves of retention varied substantially among and within process domains. The results suggest that managers who rely on natural recovery of restored sites by means of plant immigration may benefit from understanding landscape patterns when deciding upon the location of restoration measures in stream networks.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
connectivity, hydrochory, lakes, northern Sweden, process domains, propagule mimics, streams
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-161838 (URN)10.1002/eco.2091 (DOI)000474658500011 ()
Available from: 2019-08-08 Created: 2019-08-08 Last updated: 2019-08-08Bibliographically approved
Lind, L., Schuler, M. S., Hintz, W. D., Stoler, A. B., Jones, D. K., Mattes, B. M. & Relyea, R. A. (2018). Salty fertile lakes: how salinization and eutrophication alter the structure of freshwater communities. Ecosphere, 9(9), Article ID e02383.
Open this publication in new window or tab >>Salty fertile lakes: how salinization and eutrophication alter the structure of freshwater communities
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2018 (English)In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 9, no 9, article id e02383Article in journal (Refereed) Published
Abstract [en]

The quality of freshwater ecosystems is decreasing worldwide because of anthropogenic activities. For example, nutrient over-enrichment associated with agricultural, urban, and industrial development has led to an acceleration of primary production, or eutrophication. Additionally, in northern areas, deicing salts that are an evolutionary novel stressor to freshwater ecosystems have caused chloride levels of many freshwaters to exceed thresholds established for environmental protection. Even if excess nutrients and road deicing salts often contaminate freshwaters at the same time, the combined effects of eutrophication and salinization on freshwater communities are unknown. Thus by using outdoor mesocosms, we investigated the potentially interactive effects of nutrient additions and road salt (NaCl) on experimental lake communities containing phytoplankton, periphyton, filamentous algae, zooplankton, two snail species (Physa acuta and Viviparus georgianus), and macrophytes (Nitella spp.). We exposed communities to a factorial combination of environmentally relevant concentrations of road salt (15, 250, and 1000 mg Cl-/L), nutrient additions (oligotrophic, eutrophic), and sunlight (low, medium, and high) for 80 d. We manipulated light intensity to parse out the direct effects of road salts or nutrients from the indirect effects via algal blooms that reduce light levels. We observed numerous direct and indirect effects of salt, nutrients, and light as well as interactive effects. Added nutrients caused increases in most producers and consumers. Increased salt (1000 mg Cl-/L) initially caused a decline in cladoceran and copepod abundance, leading to an increase in phytoplankton. Increased salt also reduced the biomass and chl a content of Nitella and reduced the abundance of filamentous algae. Added salt had no effect on the abundance of pond snails, but it caused a decline in banded mystery snails, which led to an increase in periphyton. Low light negatively affected all taxa (except Nitella) and light levels exhibited multiple interactions with road salt, but the combined effects of nutrients and salt were always additive. Collectively, our results indicate that eutrophication and salinization both have major effects on aquatic ecosystems and their combined effects (through different mechanisms) are expected to promote large blooms of phytoplankton and periphyton while causing declines in many species of invertebrates and macrophytes.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2018
Keywords
algae, eutrophication, food web, freshwater ecosystems, macrophyte, salinization, zooplankton
National Category
Environmental Sciences Ecology
Identifiers
urn:nbn:se:umu:diva-152991 (URN)10.1002/ecs2.2383 (DOI)000446834100008 ()
Available from: 2018-11-01 Created: 2018-11-01 Last updated: 2018-11-01Bibliographically approved
Nilsson, C., Sarneel, J. M., Palm, D., Gardeström, J., Pilotto, F., Polvi, L. E., . . . Lundqvist, H. (2017). How do biota respond to additional physical restoration of restored streams?. Ecosystems (New York. Print), 20(1), 144-162
Open this publication in new window or tab >>How do biota respond to additional physical restoration of restored streams?
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2017 (English)In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 20, no 1, p. 144-162Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
fish, geomorphic complexity, hydraulics, ice, landscape scale, restoration, riparian chemistry, riparian plants, Sweden
National Category
Ecology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-131651 (URN)10.1007/s10021-016-0020-0 (DOI)000392317000015 ()
Available from: 2017-02-27 Created: 2017-02-27 Last updated: 2018-06-09Bibliographically approved
Lind, L., Alfredsen, K., Kuglerova, L. & Nilsson, C. (2016). Hydrological and thermal controls of ice formation in 25 boreal stream reaches. Journal of Hydrology, 540, 797-811
Open this publication in new window or tab >>Hydrological and thermal controls of ice formation in 25 boreal stream reaches
2016 (English)In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 540, p. 797-811Article in journal (Refereed) Published
Abstract [en]

The Northern Hemisphere has a high density of fluvial freshwater ecosystems, many of which become ice-covered during winter. The development and extent of ice have both ecological and socio-economic implications. For example, ice can cause freezing of riparian vegetation and fish eggs as well as influence hydropower production; however, when, where and why ice develops in small streams is not well known. We used observations from 25 stream reaches to study the factors controlling ice development during two consecutive winters, addressing where in the catchment surface or anchor-ice is most likely to develop, how stream morphology influences ice formation, and how climate influences ice processes. Reaches far downstream from lake outlets, or without any upstream lakes, were most prone to develop anchor-ice, but other factors also influenced ice formation. Anchor-ice was most common where water temperature and groundwater inputs were low and stream power high. Given cold air temperature and water supercooling, the in-stream substrate as well as the current velocity were also important for the development of anchor-ice. Climate and substrate seemed to be important factors for the development of surface ice. This study shows that ice processes are substantial during the hydrological year and may therefore have large implications for the ecology and engineering around boreal streams.. The study also demonstrates that ice formation in the studied streams was complex, involving many variables and physical processes. We constructed a conceptual model describing the likelihood for various ice types to develop, based on the large dataset. As such, this model will be useful for practitioners and scientists working in small watercourses in the Northern Hemisphere.

Keywords
Anchor-ice, Boreal, Channel morphology, Groundwater, River ice, Stream
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-126297 (URN)10.1016/j.jhydrol.2016.06.053 (DOI)000382269500062 ()
Available from: 2016-11-04 Created: 2016-10-03 Last updated: 2018-06-09Bibliographically approved
Lind, L. (2015). Breaking the ice: effects of ice formation and winter floods on vegetation along streams. (Doctoral dissertation). Umeå: Umeå universitet
Open this publication in new window or tab >>Breaking the ice: effects of ice formation and winter floods on vegetation along streams
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Klimatförändringar och isbildning i vattendrag : effekter på biologisk mångfald
Abstract [en]

Streams in cold regions are characterized by unique hydrological processes that control flow regime and water levels. One of the most important processes is the formation, growth and melting of different types of ice in and around the stream channel during winter. River ice controls major hydrologic events such as winter floods with magnitudes and frequencies often greater than those created by open-water conditions. While river management in northern countries has already recognized high risk of ice damages, the focus of the risk assessment has been mostly aimed towards the local economy; the ecological role of river ice has been less acknowledged. Along rivers in boreal Sweden, riparian vegetation has developed specific zonation with height and age of the plants increasing the further away they are from the stream channel. On lower levels the vegetation is often comprised of short-lived plants, such as annuals and biennials whereas more permanent woody vegetation is found at higher levels. This zonation has most often been explained by the resilience of different growth forms to the inundation regimes, such as the spring flood in northern systems. Within this framework, I investigated which factors drive the ice formation and how ice and ice-induced floods affect riparian and in-stream vegetation. A 3-year survey was conducted of ice formation and vegetation along 25 stream reaches and a set of experiments were used to evaluate ice as a disturbance agent. Reaches far away from lake outlets which had a low input of groundwater and a high velocity and stream power were most prone to form anchor ice, but many other factors also influenced ice formation. Streams with anchor ice experienced more frequent flooding of the riparian vegetation during winter. Our findings suggests that ice and winter floods favour diversity and create habitat heterogeneity for riparian species. On a community level, woody plants such as evergreen dwarf shrubs are eliminated when flooded during winter, opening up patches for other species to colonize, creating a dynamic riparian understory community. Significant changes in river ice conditions could develop with projected changes in climate which would have important geomorphologic, ecological and socio-economic impacts. One implication of climate change could be less ice disturbance and consequently a riparian vegetation in cold regions that slowly changes from forb to dwarf-shrub dominated with a subsequent decrease in species richness. Changes in species diversity and abundance of groups of species related to changes in ice formation could potentially cascade into riparian and in-stream processes such as nutrient cycling, litter decomposition and organism dispersal.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2015. p. 25
Keywords
anchor ice, climate change, in-stream, riparian, river ice, streams, vegetation
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-99008 (URN)978-91-7601-182-9 (ISBN)
Public defence
2015-02-27, Björken, Sveriges lantbruksuniversitet, Skogsmarksgränd 901 83, Umeå, 09:30 (English)
Opponent
Supervisors
Funder
Swedish Research Council Formas
Available from: 2015-02-06 Created: 2015-02-02 Last updated: 2018-06-07Bibliographically approved
Nilsson, C., Polvi, L. E. & Lind, L. (2015). Extreme events in streams and rivers in arctic and subarctic regions in an uncertain future. Freshwater Biology, 60(12), 2535-2546
Open this publication in new window or tab >>Extreme events in streams and rivers in arctic and subarctic regions in an uncertain future
2015 (English)In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 60, no 12, p. 2535-2546Article in journal (Refereed) Published
Abstract [en]

We review the predicted changes in extreme events following climate change in flowing waters in arctic and subarctic regions. These regions are characterised by tundra or taiga ecosystems in either erosional or depositional glacial landforms or presently glacierised areas of the Northern Hemisphere. The ecological and geomorphic effects of extreme meteorological and hydrological events, such as episodes of strongly increased precipitation, temperatures and flows, can be exacerbated by altered base conditions. For example, winter temperature variations between frost and thaw will become more frequent at many places because mean temperature during the winter is closer to 0 °C, potentially leading to changes in the production of ice and intensified disturbance of riparian and aquatic habitats during extreme floods. Additionally, thawing of permafrost and glaciers can lead to increased bank erosion because of thaw slump and glacial outburst floods. We discuss the abiotic and biotic effects of these and other extreme events, including heavy precipitation, floods, drought and extreme air or water temperatures, and summarise our findings in a model that aims to stimulate further research in this field.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2015
Keywords
climate change, extreme events, floods, permafrost, rivers
National Category
Oceanography, Hydrology and Water Resources Climate Research
Identifiers
urn:nbn:se:umu:diva-99006 (URN)10.1111/fwb.12477 (DOI)000364233800007 ()
Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2018-06-07Bibliographically approved
Nilsson, C., Polvi, L. E., Gardeström, J., Maher Hasselquist, E., Lind, L. & Sarneel, J. M. (2015). Riparian and in-stream restoration of boreal streams and rivers: success or failure?. Ecohydrology, 8(5), 753-764
Open this publication in new window or tab >>Riparian and in-stream restoration of boreal streams and rivers: success or failure?
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2015 (English)In: Ecohydrology, ISSN 1936-0584, E-ISSN 1936-0592, Vol. 8, no 5, p. 753-764Article in journal (Refereed) Published
Abstract [en]

We reviewed follow-up studies from Finnish and Swedish streams that have been restored after timber floating to assess the abiotic and biotic responses to restoration. More specifically, from a review of 18 case studies (16 published and 2 unpublished), we determined whether different taxonomic groups react differently or require different periods of time to respond to the same type of restoration. Restoration entailed returning coarse sediment (cobbles and boulders) and sometimes large wood to previously channelized turbulent reaches, primarily with the objective of meeting habitat requirements of naturally reproducing salmonid fish. The restored streams showed a consistent increase in channel complexity and retention capacity, but the biotic responses were weak or absent in most species groups. Aquatic mosses growing on boulders were drastically reduced shortly after restoration, but in most studies, they recovered after a few years. Riparian plants, macroinvertebrates and fish did not show any consistent trends in response. We discuss seven alternative explanations to these inconsistent results and conclude that two decades is probably too short a time for most organisms to recover. We recommend long-term monitoring using standardized methods, a landscape-scale perspective and a wider range of organisms to improve the basis for judging to what extent restoration in boreal streams has achieved its goal of reducing the impacts from timber floating.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2015
Keywords
recovery, restoration, streams, timber floating
National Category
Oceanography, Hydrology and Water Resources Environmental Sciences Ecology
Identifiers
urn:nbn:se:umu:diva-107307 (URN)10.1002/eco.1480 (DOI)000358538800002 ()
Note

Special Issue:Restoring functional riparian ecosystems: concepts and applications

Available from: 2015-08-24 Created: 2015-08-21 Last updated: 2018-06-07Bibliographically approved
Hasselquist, E. M., Nilsson, C., Hjalten, J., Jørgensen, D., Lind, L. & Polvi, L. E. (2015). Time for recovery of riparian plants in restored northern Swedish streams: a chronosequence study. Ecological Applications, 25(5), 1373-1389
Open this publication in new window or tab >>Time for recovery of riparian plants in restored northern Swedish streams: a chronosequence study
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2015 (English)In: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 25, no 5, p. 1373-1389Article in journal (Refereed) Published
Abstract [en]

A lack of ecological responses in stream restoration projects has been prevalent throughout recent literature with many studies reporting insufficient time for recovery. We assessed the relative importance of time, site variables, and landscape setting for understanding how plant species richness and understory productivity recover over time in riparian zones of northern Swedish streams. We used a space-for-time substitution consisting of 13 stream reaches restored 5-25 years ago, as well as five unrestored channelized reference reaches. We inventoried the riparian zone for all vascular plant species along 60-m study reaches and quantified cover and biomass in plots. We found that while species richness increased with time, understory biomass decreased. Forbs made up the majority of the species added, while the biomass of graminoids decreased the most over time, suggesting that the reduced dominance of graminoids favored less productive forbs. Species richness and density patterns could be attributed to dispersal limitation, with anemochorous species being more associated with time after restoration than hydrochorous, zoochorous, or vegetatively reproducing species. Using multiple linear regression, we found that time along with riparian slope and riparian buffer width (e.g., distance to logging activities) explained the most variability in species richness, but that variability in total understory biomass was explained primarily by time. The plant community composition of restored reaches differed from that of channelized references, but the difference did not increase over time. Rather, different time categories had different successional trajectories that seemed to converge on a unique climax community for that time period. Given our results, timelines for achieving species richness objectives should be extended to 25 years or longer if recovery is defined as a saturation of the accumulation of species over time. Other recommendations include making riparian slopes as gentle as possible given the landscape context and expanding riparian buffer width for restoration to have as much impact as possible.

Keywords
boreal forest, buffer strip, chronosequence, riparian buffer, riparian slope, river restoration, seed dispersal, space-for-time substitution, time gradient, vegetation
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-106561 (URN)10.1890/14-1102.1 (DOI)000356898400017 ()
Available from: 2015-07-20 Created: 2015-07-20 Last updated: 2018-06-07Bibliographically approved
Lind, L. & Nilsson, C. (2015). Vegetation patterns in small boreal streams relate to ice and winter floods. Journal of Ecology, 103(2), 431-440
Open this publication in new window or tab >>Vegetation patterns in small boreal streams relate to ice and winter floods
2015 (English)In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 103, no 2, p. 431-440Article in journal (Refereed) Published
Abstract [en]

In-stream and riparian vegetation are species rich, productive and dynamic. Their patterns insmall boreal streams are largely driven by seasonal flow regimes. Traditionally, flow-related processes during the growing season, particularly the spring flood, have been seen as the most important, whereas vegetation has been viewed as being dormant and ‘less affected’ during winter.

Riparian and in-stream vegetation were inventoried during the summers 2011–2013 in eight reaches of northern Swedish streams. Along each reach, the ice formation was surveyed during winter by visual inspections and with permanently placed cameras. We then evaluated the potential effects of ice regimes and winter flooding on riparian and in-stream vegetation during 3 years by relating the abundance of winter floods caused by anchor ice to the cover, composition and biomass of vegetation.

We found that the numbers of winter floods were higher along reaches with anchor-ice formation than in reaches without. We also found that species diversity of riparian vegetation was higher inthe reaches with anchor ice. This resulted from a lower cover of riparian dwarf shrubs and a higher cover of graminoids and forbs along reaches with anchor ice. We also found a lower cover of instream algae but a higher cover of bryophytes in anchor-ice reaches. These patterns were consistent throughout the study period although there were interannual differences in temperature, water levels and ice cover.

During our study period, we encountered an average of 20 shifts per winter between freezing and thawing, while there was an average of 10 shifts per winter during 1960–1990. This indicates a warming climate in high latitudes. Higher temperatures and more shifts between freezing and thawing may initially increase ice dynamics. However, with further increases in mean temperature, ice production should eventually decrease.

Synthesis. Ice and winter floods caused by anchor ice appear to be important disturbance agents that allow less competitive species to establish along small boreal streams. If ice dynamics is reduced, the composition and production of riparian and in-stream vegetation may be changed, with possible consequences for the entire stream ecosystem.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2015
Keywords
anchor ice, bryophytes, climate change, determinants of plant community diversity and structure, disturbance, ice regime, riparian, vascular plants, vegetation, winter flooding
National Category
Ecology
Research subject
Ecological Botany; Hydrology
Identifiers
urn:nbn:se:umu:diva-98969 (URN)10.1111/1365-2745.12355 (DOI)000350549000014 ()
Funder
Swedish Research Council Formas
Available from: 2015-02-02 Created: 2015-01-30 Last updated: 2018-06-07Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7212-8121

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