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Sarneel, J. M., Hefting, M. M., Kowalchuk, G. A., Nilsson, C., Van der Velden, M., Visser, E. J. W., . . . Jansson, R. (2019). Alternative transient states and slow plant community responses after changed flooding regimes. Global Change Biology, 25(4), 1358-1367
Open this publication in new window or tab >>Alternative transient states and slow plant community responses after changed flooding regimes
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2019 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 25, no 4, p. 1358-1367Article in journal (Refereed) Published
Abstract [en]

Climate change will have large consequences for flooding frequencies in freshwater systems. In interaction with anthropogenic activities (flow regulation, channel restoration and catchment land-use) this will both increase flooding and drought across the world. Like in many other ecosystems facing changed environmental conditions, it remains difficult to predict the rate and trajectory of vegetation responses to changed conditions. Given that critical ecosystem services (e.g. bank stabilization, carbon subsidies to aquatic communities or water purification) depend on riparian vegetation composition, it is important to understand how and how fast riparian vegetation responds to changing flooding regimes. We studied vegetation changes over 19 growing seasons in turfs that were transplanted in a full-factorial design between three riparian elevations with different flooding frequencies. We found that (a) some transplanted communities may have developed into an alternative stable state and were still different from the target community, and (b) pathways of vegetation change were highly directional but alternative trajectories did occur, (c) changes were rather linear but faster when flooding frequencies increased than when they decreased, and (d) we observed fastest changes in turfs when proxies for mortality and colonization were highest. These results provide rare examples of alternative transient trajectories and stable states under field conditions, which is an important step towards understanding their drivers and their frequency in a changing world.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
alternative stable states, drought events, flood regime change, hydrological alterations, hysteresis, riparian vegetation, river restoration, species traits
National Category
Ecology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-157948 (URN)10.1111/gcb.14569 (DOI)000461817500013 ()30638293 (PubMedID)
Available from: 2019-04-18 Created: 2019-04-18 Last updated: 2019-04-18Bibliographically approved
Sarneel, J. M., Bejarano, M. D., van Oosterhout, M. & Nilsson, C. (2019). Local flooding history affects plant recruitment in riparian zones. Journal of Vegetation Science, 30(2), 224-234
Open this publication in new window or tab >>Local flooding history affects plant recruitment in riparian zones
2019 (English)In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 30, no 2, p. 224-234Article in journal (Refereed) Published
Abstract [en]

Aims: Many rivers across the globe are severely impacted by changed flooding regimes, resulting in drastic shifts in vegetation, but the processes driving the exchange of flood‐sensitive and flood‐tolerant species are understood less. We studied the role of long‐term and recent flooding histories for riparian plant recruitment in response to various changes in flooding regime.

Location: Vindel River catchment (Northern Sweden).

Methods

We experimentally changed long‐term flooding regimes by transplanting turfs between high and low elevations in 2000 and in 2014 (= 8 per treatment). We sowed seeds of five riparian species in both transplanted turfs and non‐transplanted controls and counted seedling numbers over two growing seasons. Further, we inventoried natural seedling frequencies in 190 plots in 19 reaches in 2013 and 2014, and related natural seedling numbers to plot flooding history in the period 2012–2014.

Results: We observed effects of long‐term flooding history in the second year of the transplantation study (2015), but not in the first year. In 2015, turfs transplanted to locations with less flooding resulted in higher plant recruitment while transplantation to sites with more frequent flooding reduced recruitment compared to the controls. Since these differences were only found in recently transplanted turfs and not in older turfs, the legacy effect of long‐term flooding history can be transient. In the field seedling survey, similar differences were found between flooding‐history categories in 2013, but not in 2014, when the moisture conditions of the most recent year determined flooding. Further, lowest seedling numbers were observed when the previous flooding occurred in winter, and higher seedling numbers when floods occurred in spring or not at all.

Conclusions: Both long‐term and recent flooding histories can affect plant recruitment, and their influence should be taken into account when designing restoration projects.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
dispersal filtering, environmental filtering, flood dynamics, historic contingency, legacy effects, plant recruitment window, regime shifts, window of opportunity, zonation
National Category
Forest Science
Identifiers
urn:nbn:se:umu:diva-160317 (URN)10.1111/jvs.12731 (DOI)000466421500005 ()
Available from: 2019-06-17 Created: 2019-06-17 Last updated: 2019-06-17Bibliographically approved
Fanin, N., Bezaud, S., Sarneel, J. M., Cecchini, S., Nicolas, M. & Augusto, L. (2019). Relative Importance of Climate, Soil and Plant Functional Traits During the Early Decomposition Stage of Standardized Litter. Ecosystems (New York. Print)
Open this publication in new window or tab >>Relative Importance of Climate, Soil and Plant Functional Traits During the Early Decomposition Stage of Standardized Litter
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2019 (English)In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629Article in journal (Refereed) Epub ahead of print
Abstract [en]

Climatic factors have long been considered predominant in controlling decomposition rates at large spatial scales. However, recent research suggests that edaphic factors and plant functional traits may play a more important role than previously expected. In this study, we investigated how biotic and abiotic factors interacted with litter quality by analyzing decomposition rates for two forms of standardized litter substitutes: green tea (high-quality litter) and red tea (low-quality litter). We placed 1188 teabags at two different positions (forest floor and 8 cm deep) across 99 forest sites in France and measured 46 potential drivers at each site. We found that high-quality litter decomposition was strongly related to climatic factors, whereas low-quality litter decomposition was strongly related to edaphic factors and the identity of the dominant tree species in the stand. This indicates that the relative importance of climate, soil and plant functional traits in the litter decomposition process depends on litter quality, which was the predominant factor controlling decomposition rate in this experiment. We also found that burying litter increased decomposition rates, and that this effect was more important for green tea in drier environments. This suggests that changes in position (surface vs. buried) at the plot scale may be as important as the role of macroclimate on decomposition rates because of varying water availability along the soil profile. Acknowledging that the effect of climate on decomposition depends on litter quality and that the macroclimate is not necessarily the predominant factor at large spatial scales is the first step toward identifying the factors regulating decomposition rates from the local scale to the global scale.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Carbon turnover, climate, decomposition, nutrient cycling, plant traits, tea bag index, soil depth, soil parent material, soil properties
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-164981 (URN)10.1007/s10021-019-00452-z (DOI)000490851500001 ()
Available from: 2019-11-12 Created: 2019-11-12 Last updated: 2019-11-12
Nilsson, C., Riis, T., Sarneel, J. M. & Svavarsdóttir, K. (2018). Ecological Restoration as a Means of Managing Inland Flood Hazards. BioScience, 68(2), 89-99
Open this publication in new window or tab >>Ecological Restoration as a Means of Managing Inland Flood Hazards
2018 (English)In: BioScience, ISSN 0006-3568, E-ISSN 1525-3244, Vol. 68, no 2, p. 89-99Article in journal (Refereed) Published
Abstract [en]

Many streams and rivers experience major floods. Historically, human societies have responded to such floods by moving away from them or by abating them, the latter with large negative impacts on stream and river ecology. Societies are currently implementing a strategy of "living with floods,"which may involve ecological restoration. It further involves flood mapping, forecasting, and warning systems. We evaluate 14 different stream-and river-restoration measures, which differ in their capacity to modify water retention and runoff. We discuss these restoration measures in the light of predicted changes in climate and flooding and discuss future restoration needs. We focus on the Nordic countries, where substantial changes in the water cycle are foreseen. We conclude that sustainable solutions require researchers to monitor the effect of flood management and study the relative importance of individual restoration measures, as well as the side effects of flood attenuation.

Place, publisher, year, edition, pages
Oxford University Press, 2018
Keywords
climate change, restoration/remediation, river ecology, ecosystem engineering, hydrology
National Category
Ecology Climate Research Environmental Sciences Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:umu:diva-145379 (URN)10.1093/biosci/bix148 (DOI)000424878000006 ()
Available from: 2018-03-09 Created: 2018-03-09 Last updated: 2019-04-18Bibliographically approved
Polvi, L. E. & Sarneel, J. M. (2018). Ecosystem engineers in rivers: An introduction to how and where organisms create positive biogeomorphic feedbacks. WIREs Water, 5(2), Article ID e1271.
Open this publication in new window or tab >>Ecosystem engineers in rivers: An introduction to how and where organisms create positive biogeomorphic feedbacks
2018 (English)In: WIREs Water, ISSN 0935-879X, E-ISSN 2049-1948, Vol. 5, no 2, article id e1271Article in journal (Refereed) Published
Abstract [en]

Ecosystem engineers substantially alter physical flow characteristics and shape a river's form and function. Because the recurrence interval of geomorphic processes and disturbances in rivers commonly match the temporal scale of plants' life cycles or alterations by animals, the resulting feedbacks are an important component of rivers. In this review, we focus on biota that directly or indirectly induce a physical change in rivers and cause positive feedbacks on the functioning of that organism. We provide an overview of how various ecosystem engineers affect rivers at different temporal and spatial scales and plot them on a conceptual gradient of river types. Various plants engineer the river environment through stabilizing sediment and reducing flow velocities, including macrophytes, woody plants, and algal mats and biofilms. Among animals that engineer, beaver that build dams cause substantial changes to river dynamics. In addition, benthic macroinvertebrates and mussels can stabilize sediment and reduce velocities, and aquatic and riparian grazers modulate the effect of plants. Humans are also considered river ecosystem engineers. Most of the ecosystem engineers reported in literature occur in rivers with low to intermediate relative stability, intermediate channel widths, and small to intermediate grain sizes. Ecosystem engineers that create positive biogeomorphic feedbacks are important to take into account when managing river systems, as many common invasive species are successful due to their engineering capabilities. River restoration can use ecosystem engineers to spur holistic recovery. Future research points towards examining ecosystem engineers on longer spatial and temporal scales and understanding the co-evolution of organisms and landforms through engineering. 

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-146155 (URN)10.1002/wat2.1271 (DOI)000425438800007 ()
Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2019-04-18Bibliographically approved
Bakker, E. S., Veen, C. G. F., Ter Heerdt, G. J. N., Huig, N. & Sarneel, J. M. (2018). High grazing pressure of geese threatens conservation and restoration of reed belts. Frontiers in Plant Science, 9, Article ID 1649.
Open this publication in new window or tab >>High grazing pressure of geese threatens conservation and restoration of reed belts
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2018 (English)In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 9, article id 1649Article in journal (Refereed) Published
Abstract [en]

Reed (Phragmites australis (Cav.) Trin. ex Steud.) beds are important habitat for marsh birds, but are declining throughout Europe. Increasing numbers of the native marsh bird, the Greylag goose (Anser anser L.), are hypothesized to cause reed bed decline and inhibit restoration of reed beds, but data are largely lacking. In this study, we experimentally tested the effect of grazing by Greylag geese on the growth and expansion of reed growing in belts along lake shorelines. After 5 years of protecting reed from-grazing with exclosures, reed stems were over 4-fold denser and taller than in the grazed plots. Grazing pressure was intense with 50-100% of the stems being grazed among years in the control plots open to grazing. After 5 years of protection we opened half of the exclosures and the geese immediately grazed almost 100% of the reed stems. Whereas this did not affect the reed stem density, the stem height was strongly reduced and similar to permanently grazed reed. The next year geese were actively chased away by management from mid-March to mid-June, which changed the maximum amount of geese from over 2300 to less than 50. As a result, reed stem density and height increased and the reed belt had recovered over the full 6 m length of the experimental plots. Lastly, we introduced reed plants in an adjacent lake where no reed was growing and geese did visit this area. After two years, the density of the planted reed was six to nine-fold higher and significantly taller in exclosures compared to control plots where geese had access to the reed plants. We conclude that there is a conservation dilemma regarding how to preserve and restore reed belts in the presence of high densities of Greylag geese as conservation of both reed belts and high goose numbers seems infeasible. We suggest that there are three possible solutions for this dilemma: (1) effects of the geese can be mediated by goose population management, (2) the robustness of the reed marshes can be increased, and (3) at the landscape level, spatial planning can be used to configure landscapes with large reed bed reserves surrounded by unmown, unfertilized meadows.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2018
Keywords
Anser anser, aquatic plant, exclosure, herbivory, landscape configuration, Phragmites australis, storation, wetland
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-153639 (URN)10.3389/fpls.2018.01649 (DOI)000449842900001 ()
Funder
Swedish Research Council
Available from: 2018-11-27 Created: 2018-11-27 Last updated: 2018-11-27Bibliographically approved
Althuizen, I. H. J., Lee, H., Sarneel, J. M. & Vandvik, V. (2018). Long-Term climate regime modulates the impact of short-term climate variability on decomposition in alpine grassland soils. Ecosystems (New York. Print), 21(8), 1580-1592
Open this publication in new window or tab >>Long-Term climate regime modulates the impact of short-term climate variability on decomposition in alpine grassland soils
2018 (English)In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 21, no 8, p. 1580-1592Article in journal (Refereed) Published
Abstract [en]

Decomposition of plant litter is an important process in the terrestrial carbon cycle and makes up approximately 70% of the global carbon flux from soils to the atmosphere. Climate change is expected to have significant direct and indirect effects on the litter decomposition processes at various timescales. Using the TeaBag Index, we investigated the impact on decomposition of short-term direct effects of temperature and precipitation by comparing temporal variability over years, versus long-term climate impacts that incorporate indirect effects mediated through environmental changes by comparing sites along climatic gradients. We measured the initial decomposition rate (k) and the stabilization factor (S; amount of labile litter stabilizing) across a climate grid combining three levels of summer temperature (6.5-10.5 degrees C) with four levels of annual precipitation (600-2700 mm) in three summers with varying temperature and precipitation. Several (a)biotic factors were measured to characterize environmental differences between sites. Increased temperatures enhanced k, whereas increased precipitation decreased k across years and climatic regimes. In contrast, S showed diverse responses to annual changes in temperature and precipitation between climate regimes. Stabilization of labile litter fractions increased with temperature only in boreal and sub-alpine sites, while it decreased with increasing precipitation only in sub-alpine and alpine sites. Environmental factors such as soil pH, soil C/N, litter C/N, and plant diversity that are associated with long-term climate variation modulate the response of k and S. This highlights the importance of long-term climate in shaping the environmental conditions that influences the response of decomposition processes to climate change.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
decomposition, climate change, temperature, precipitation, litter bag, annual variability, grassland, tea bag index
National Category
Climate Research
Identifiers
urn:nbn:se:umu:diva-154028 (URN)10.1007/s10021-018-0241-5 (DOI)000450919700007 ()
Funder
Swedish Research Council
Available from: 2018-12-20 Created: 2018-12-20 Last updated: 2018-12-20Bibliographically 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
Sarneel, J. M. & Veen, G. F. (2017). Legacy effects of altered flooding regimes on decomposition in a boreal floodplain. Plant and Soil, 421(1-2), 57-66
Open this publication in new window or tab >>Legacy effects of altered flooding regimes on decomposition in a boreal floodplain
2017 (English)In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 421, no 1-2, p. 57-66Article in journal (Refereed) Published
Abstract [en]

Since long-term experiments are scarce, we have poor understanding of how changed flooding regimes affect processes such as litter decomposition. We simulated short- and long-term changed flooding regimes by transplanting turfs between low (frequently flooded) and high (in-frequently flooded) elevations on the river bank in 2000 (old turfs) and 2014 (young turfs). We tested how incubation elevation, turf origin and turf age affected decomposition of standard litter (tea) and four types of local litter. For tea, we found that the initial decomposition rate (k) and stabilization (S) of labile material during the second decomposition phase were highest at high incubation elevation. We found intermediate values for k and S in young transplanted turfs, but turf origin was not important in old turfs. Local litter mass loss was generally highest at high incubation elevations, and effects of turf origin and turf age were litter-specific. We conclude that incubation elevation, i.e., the current flooding regime, was the most important factor driving decomposition. Soil origin (flooding history) affected decomposition of tea only in young turfs. Therefore, we expect that changes in flooding regimes predominantly affect decomposition directly, while indirect legacy effects are weaker and litter- or site-specific.

Place, publisher, year, edition, pages
Springer, 2017
Keywords
River management, Ecosystem function, TBI, Tea bag method, Floodplain, Boreal zone
National Category
Geosciences, Multidisciplinary Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:umu:diva-143558 (URN)10.1007/s11104-017-3382-y (DOI)000417721600006 ()
Available from: 2018-01-04 Created: 2018-01-04 Last updated: 2018-06-09Bibliographically approved
Herberg, E. R. & Sarneel, J. M. (2017). Recruitment of riparian plants after restoration of geomorphic complexity in northern Sweden. Applied Vegetation Science, 20(3), 435-445
Open this publication in new window or tab >>Recruitment of riparian plants after restoration of geomorphic complexity in northern Sweden
2017 (English)In: Applied Vegetation Science, ISSN 1402-2001, E-ISSN 1654-109X, Vol. 20, no 3, p. 435-445Article in journal (Refereed) Published
Abstract [en]

Question: Restoration of channelized streams increases geomorphic complexity but it remains unclear how this interacts with processes that drive future vegetation changes (dispersal, germination and establishment). This study asks if increased geomorphic complexity increases recruitment conditions of sown seeds or affects post-dispersal natural seedling densities. Location: Vindel River catchment, northern Sweden. Methods: We selected seven study streams with paired reaches that differed in the degree to which geomorphic complexity was restored. Basic reaches used simple restoration methods while enhanced reaches additionally added large boulders and woody debris. We sowed seeds of six species at ten locations in each reach in 2014 and counted the number of seedlings after 8wk and the number of naturally occurring seedlings in a plot adjacent to the sowing locations in 2013 and 2014. Using factor analysis based on 34 complexity measurements, overall geomorphic complexity was quantified for eight of the 14 reaches. Results: Total numbers of sown (2014) and natural seedlings (2013 and 2014) summed per reach did not differ between restoration types when tested pair-wise. Enhanced restoration did not always significantly increase geomorphic complexity, which differed considerably between the streams. More complex reaches were steeper, had larger size sediment and more nutrient-poor soils. Total recruitment of sown species significantly decreased with increasing complexity. Numbers of natural seedlings differed considerably from 2013 to 2014, but were not related to complexity. In 2014, a potential parent plant of the same species occurred within the same plot for 71.8% of the natural seedlings that could be identified. Conclusions: The recruitment of sown seeds was affected by overall geomorphic complexity rather than by the enhanced restoration. The absence of a correlation between geomorphic complexity and natural seedlings could indicate that natural seedling dynamics are not solely determined by recruitment conditions, but also by dispersal.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
Keywords
Boreal streams, Dispersal, Establishment, Flooding, Flow regime, Germination, Large woody debris, Recruitment, Restoration, Riparian vegetation, Sediment
National Category
Ecology Forest Science
Identifiers
urn:nbn:se:umu:diva-137612 (URN)10.1111/avsc.12304 (DOI)000403676000012 ()
Available from: 2017-07-10 Created: 2017-07-10 Last updated: 2018-06-09Bibliographically approved
Projects
Tea time for science [2014-04270_VR]; Umeå University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6187-499x

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