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Tiwari, T., Sponseller, R. A. & Laudon, H. (2019). Contrasting responses in dissolved organic carbon to extreme climate events from adjacent boreal landscapes in Northern Sweden [Letter to the editor]. Environmental Research Letters, 14(8), Article ID 084007.
Open this publication in new window or tab >>Contrasting responses in dissolved organic carbon to extreme climate events from adjacent boreal landscapes in Northern Sweden
2019 (English)In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 14, no 8, article id 084007Article in journal, Letter (Refereed) Published
Abstract [en]

The ongoing pressures of climate change, as expressed by the increased intensity, duration, and frequency of temperature and precipitation events, threatens the storage of carbon in northern latitudes. One key concern is how these events will affect the production, mobilization, and export of dissolved organic carbon (DOC), the main form of aquatic carbon export in these regions. In this study, we retrospectively show contrasting effects of climate extremes over 23 years on two adjacent boreal catchments, one dominated by forest cover and the other draining a mire (wetland), despite experiencing the same extreme climate events. During the peak snowmelt, DOC concentrations ranged from 20 to 33 mg l(-1) in the forest catchment and 10-28 mg l(-1) in the mire catchment respectively, highlighting large inter-annual variation in the springtime hydrologicCexport at both sites. Weused climate and discharge variables to predict this variation, and found that DOC from the forested catchment, which is derived largely from riparian soils, had the highest concentrations following cold summers, dry autumns, and winters with high precipitation. By contrast, in the mire outlet, where DOC is primarily derived from decomposing peat, the highest DOC concentrations in the spring followed cold/dry winters and dry summers. Our results indicate that processes regulating stream DOC concentrations during spring in both catchments were dependent on both temperature and precipitation in multiple seasons. Together, these patterns suggest that DOC responses to climatic extremes are complex and generate variable patterns in springtime concentrations that are strongly dependent upon landscape context.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
Keywords
extreme climate events, boreal streams, peatland, boreal forest, climate change, water quality, ssolve organic carbon
National Category
Climate Research
Identifiers
urn:nbn:se:umu:diva-161981 (URN)10.1088/1748-9326/ab23d4 (DOI)000476829600007 ()
Available from: 2019-08-14 Created: 2019-08-14 Last updated: 2019-08-22Bibliographically approved
Lupon, A., Denfeld, B. A., Laudon, H., Leach, J., Karlsson, J. & Sponseller, R. A. (2019). Groundwater inflows control patterns and sources of greenhouse gas emissions from streams. Limnology and Oceanography, 64(4), 1545-1557
Open this publication in new window or tab >>Groundwater inflows control patterns and sources of greenhouse gas emissions from streams
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2019 (English)In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 64, no 4, p. 1545-1557Article in journal (Refereed) Published
Abstract [en]

Headwater streams can be important sources of carbon dioxide (CO2) and methane (CH4) to the atmosphere. However, the influence of groundwater-stream connectivity on the patterns and sources of carbon (C) gas evasion is still poorly understood. We explored these connections in the boreal landscape through a detailed study of a 1.4 km lake outlet stream that is hydrologically fed by multiple topographically driven groundwater input zones. We measured stream and groundwater dissolved organic C (DOC), CO2, and CH4 concentrations every 50 m biweekly during the ice-free period and estimated in-stream C gas production through a mass balance model and independent estimates of aquatic metabolism. The spatial pattern of C gas concentrations was consistent over time, with peaks of both CH4 and CO2 concentrations occurring after each groundwater input zone. Moreover, lateral C gas inputs from riparian soils were the major source of CO2 and CH4 to the stream. DOC mineralization and CH4 oxidation within the stream accounted for 17-51% of stream CO2 emissions, and this contribution was the greatest during relatively higher flows. Overall, our results illustrate how the nature and arrangement of groundwater flowpaths can organize patterns of stream C concentrations, transformations, and emissions by acting as a direct source of gases and by supplying organic substrates that fuel aquatic metabolism. Hence, refined assessments of how catchment structure influences the timing and magnitude of groundwater-stream connections are crucial for mechanistically understanding and scaling C evasion rates from headwaters.

National Category
Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:umu:diva-161831 (URN)10.1002/lno.11134 (DOI)000474301200009 ()
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-08-12Bibliographically approved
Rocher-Ros, G., Sponseller, R. A., Lidberg, W., Mörth, C.-M. & Giesler, R. (2019). Landscape process domains drive patterns of CO2 evasion from river networks [Letter to the editor]. Limnology and Oceanography Letters, 4(4), 87-95
Open this publication in new window or tab >>Landscape process domains drive patterns of CO2 evasion from river networks
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2019 (English)In: Limnology and Oceanography Letters, ISSN 2378-2242, Vol. 4, no 4, p. 87-95Article in journal, Letter (Refereed) Published
Abstract [en]

Streams are important emitters of CO2 but extreme spatial variability in their physical properties can make upscaling very uncertain. Here, we determined critical drivers of stream CO2 evasion at scales from 30 to 400 m across a 52.5 km2 catchment in northern Sweden. We found that turbulent reaches never have elevated CO2 concentrations, while less turbulent locations can potentially support a broad range of CO2 concentrations, consistent with global observations. The predictability of stream pCO2 is greatly improved when we include a proxy for soil‐stream connectivity. Catchment topography shapes network patterns of evasion by creating hydrologically linked “domains” characterized by high water‐atmosphere exchange and/or strong soil‐stream connection. This template generates spatial variability in the drivers of CO2 evasion that can strongly bias regional and global estimates. To overcome this complexity, we provide the foundations of a mechanistic framework of CO2 evasion by considering how landscape process domains regulate transfer and supply.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
National Category
Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:umu:diva-158874 (URN)10.1002/lol2.10108 (DOI)000474692600001 ()
Funder
Swedish Research Council, 2013‐5001
Available from: 2019-05-13 Created: 2019-05-13 Last updated: 2019-08-12Bibliographically approved
Truchy, A., Göthe, E., Angeler, D. G., Ecke, F., Sponseller, R. A., Bundschuh, M., . . . McKie, B. G. (2019). Partitioning spatial, environmental, and community drivers of ecosystem functioning. Landscape Ecology, 34(10), 2371-2384
Open this publication in new window or tab >>Partitioning spatial, environmental, and community drivers of ecosystem functioning
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2019 (English)In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 34, no 10, p. 2371-2384Article in journal (Refereed) Published
Abstract [en]

Context: Community composition, environmental variation, and spatial structuring can influence ecosystem functioning, and ecosystem service delivery. While the role of space in regulating ecosystem functioning is well recognised in theory, it is rarely considered explicitly in empirical studies.

Objectives: We evaluated the role of spatial structuring within and between regions in explaining the functioning of 36 reference and human-impacted streams.

Methods: We gathered information on regional and local environmental variables, communities (taxonomy and traits), and used variance partitioning analysis to explain seven indicators of ecosystem functioning.

Results: Variation in functional indicators was explained not only by environmental variables and community composition, but also by geographic position, with sometimes high joint variation among the explanatory factors. This suggests spatial structuring in ecosystem functioning beyond that attributable to species sorting along environmental gradients. Spatial structuring at the within-region scale potentially arose from movements of species and materials among habitat patches. Spatial structuring at the between-region scale was more pervasive, occurring both in analyses of individual ecosystem processes and of the full functional matrix, and is likely to partly reflect phenotypic variation in the traits of functionally important species. Characterising communities by their traits rather than taxonomy did not increase the total variation explained, but did allow for a better discrimination of the role of space.

Conclusions: These results demonstrate the value of accounting for the role of spatial structuring to increase explanatory power in studies of ecosystem processes, and underpin more robust management of the ecosystem services supported by those processes.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Spatial structuring, Community ecology, Ecosystem processes, Species traits, Variance partitioning
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-165001 (URN)10.1007/s10980-019-00894-9 (DOI)000490066800013 ()
Available from: 2019-11-07 Created: 2019-11-07 Last updated: 2019-11-07Bibliographically approved
Denfeld, B. A., Klaus, M., Laudon, H., Sponseller, R. A. & Karlsson, J. (2018). Carbon Dioxide and Methane Dynamics in a Small Boreal Lake During Winter and Spring Melt Events. Journal of Geophysical Research - Biogeosciences, 123(8), 2527-2540
Open this publication in new window or tab >>Carbon Dioxide and Methane Dynamics in a Small Boreal Lake During Winter and Spring Melt Events
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2018 (English)In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 123, no 8, p. 2527-2540Article in journal (Refereed) Published
Abstract [en]

In seasonally ice‐covered lakes, carbon dioxide (CO2) and methane (CH4) emission at ice‐off can account for a significant fraction of the annual budget. Yet knowledge of the mechanisms controlling below lake‐ice carbon (C) dynamics and subsequent CO2 and CH4 emissions at ice‐off is limited. To understand the control of below ice C dynamics, and C emissions in spring, we measured spatial variation in CO2, CH4, and dissolved inorganic and organic carbon from ice‐on to ice‐off, in a small boreal lake during a winter with sporadic melting events. Winter melt events were associated with decreased surface water DOC in the forest‐dominated basin and increased surface water CH4 in the mire‐dominated basin. At the whole‐lake scale, CH4 accumulated below ice throughout the winter, whereas CO2 accumulation was greatest in early winter. Mass‐balance estimates suggest that, in addition to the CO2 and CH4 accumulated during winter, external inputs of CO2 and CH4 and internal processing during ice‐melt could represent significant sources of C gas emissions during ice‐off. Moreover, internal processing of CO2 and CH4 worked in opposition, with production of CO2 and oxidation of CH4 dominating at ice‐off. These findings have important implications for how small boreal lakes will respond to warmer winters in the future; increased winter melt events will likely increase external inputs below ice and thus alter the extent and timing of CO2 and CH4 emissions to the atmosphere at ice‐off.

Keywords
winter limnology, carbon cycle, carbon dioxide, methane emissions, ice‐covered lake
National Category
Climate Research
Identifiers
urn:nbn:se:umu:diva-152552 (URN)10.1029/2018JG004622 (DOI)000445731100016 ()2-s2.0-85052445907 (Scopus ID)
Available from: 2018-10-11 Created: 2018-10-11 Last updated: 2018-10-12Bibliographically approved
Jonsson, M., Polvi, L. E., Sponseller, R. A. & Stenroth, K. (2018). Catchment properties predict autochthony in stream filter feeders. Hydrobiologia, 815(1), 83-95
Open this publication in new window or tab >>Catchment properties predict autochthony in stream filter feeders
2018 (English)In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 815, no 1, p. 83-95Article in journal (Refereed) Published
Abstract [en]

Stream ecological theory predicts that the use of allochthonous resources declines with increasing channel width, while at the same time primary production and autochthonous carbon use by consumers increase. Although these expectations have found support in several studies, it is not well known how terrestrial runoff and/or inputs of primary production from lakes alter these longitudinal patterns. To investigate this, we analyzed the diet of filter-feeding black fly and caddisfly larvae from 23 boreal streams, encompassing gradients in drainage area, land cover and land use, and distance to nearest upstream lake outlet. In five of these streams, we also sampled repeatedly during autumn to test if allochthony of filter feeders increases over time as new litter inputs are processed. Across sites, filter-feeder autochthony was 21.1-75.1%, did not differ between black fly and caddisfly larvae, was not positively related to drainage area, and did not decrease with distance from lakes. Instead, lake and wetland cover promoted filter-feeder autochthony independently of stream size, whereas catchment-scale forest cover and forestry reduced autochthony. Further, we found no seasonal increase in allochthony, indicating low assimilation of particles derived from autumn litter fall. Hence, catchment properties, rather than local conditions, can influence levels of autochthony in boreal streams.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Allochthony, Aquatic insects, Autochthony, Land cover, Land use, Stream
National Category
Ecology Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:umu:diva-148625 (URN)10.1007/s10750-018-3553-8 (DOI)000428815800007 ()
Available from: 2018-06-26 Created: 2018-06-26 Last updated: 2018-08-16Bibliographically approved
Tiwari, T., Sponseller, R. A. & Laudon, H. (2018). Extreme climate effects on dissolved organic carbon concentrations during snowmelt. Journal of Geophysical Research - Biogeosciences, 123(4), 1277-1288
Open this publication in new window or tab >>Extreme climate effects on dissolved organic carbon concentrations during snowmelt
2018 (English)In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 123, no 4, p. 1277-1288Article in journal (Refereed) Published
Abstract [en]

Extreme weather and climate events are predicted to increase in frequency and severity in the near future, which could have detrimental consequences for water quality in northern latitudes. Key processes that regulate the production and transport of solutes, like dissolved organic carbon (DOC), from soils to streams can be potentially altered by episodes of extreme temperature and/or precipitation. Here we use an intensively studied research catchment in northern Sweden with 23 years of data to ask how extreme antecedent climate events influence DOC concentration during snowmelt. Specifically, we used a combination of principal components analysis, cluster analysis, and multivariate partial least square analysis to show that almost every year provides some combination of extreme conditions in terms of intensity, duration, or frequency of temperature and/or rainfall. However, in terms of DOC responses to these events, variations in peak concentrations were most closely related to cold winter conditions, winter precipitation (snow), and temperature during the previous autumn. Specifically, years with most severe frost and icing during winter, but low winter precipitation, previous summer precipitation, and warmer autumns, showed the highest peaks in concentrations. In contrast, the lowest peak DOC concentrations were observed during spring snowmelt following high summer precipitation, colder autumns, and high winter precipitation. While this research highlights the importance of winter climate for influencing the DOC concentration during the spring, it also points to the potential importance of lag effects from preceding seasons on responses observed during the snowmelt season.

Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2018
National Category
Environmental Sciences related to Agriculture and Land-use
Identifiers
urn:nbn:se:umu:diva-148837 (URN)10.1002/2017JG004272 (DOI)000432012500009 ()
Available from: 2018-06-12 Created: 2018-06-12 Last updated: 2018-06-12Bibliographically approved
Sponseller, R. A., Blackburn, M., Nilsson, M. B. & Laudon, H. (2018). Headwater Mires Constitute a Major Source of Nitrogen (N) to Surface Waters in the Boreal Landscape. Ecosystems (New York. Print), 21(1), 31-44
Open this publication in new window or tab >>Headwater Mires Constitute a Major Source of Nitrogen (N) to Surface Waters in the Boreal Landscape
2018 (English)In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 21, no 1, p. 31-44Article in journal (Refereed) Published
Abstract [en]

Nutrient exports from soils have important implications for long-term patterns of nutrient limitation on land and resource delivery to aquatic environments. While plant-soil systems are notably efficient at retaining limiting nutrients, spatial and temporal mismatches in resource supply and demand may create opportunities for hydrologic losses to occur. Spatial mismatches may be particularly important in peat-forming landscapes, where the development of a two-layer vertical structure can isolate plant communities on the surface from resource pools that accumulate at depth. Our objectives were to test this idea in northern Sweden, where nitrogen (N) limitation of terrestrial plants is widespread, and where peat-forming, mire ecosystems are dominant features of the landscape. We quantified vertical patterns of N chemistry in a minerogenic mire, estimated the seasonal and annual hydrologic export of organic and inorganic N from this system, and evaluated the broader influence of mire cover on N chemistry across a stream network. Relatively high concentrations of ammonium (up to 2 mg l(-1)) were observed in groundwater several meters below the peat surface, and N was routed to the outlet stream along deep, preferential flowpaths. Areal estimates of inorganic N export from the mire were several times greater than from an adjacent, forested catchment, with markedly higher loss rates during the growing season, when plant N demand is ostensibly greatest. At broader scales, mire cover was positively correlated with long-term concentrations of inorganic and organic N in streams across the drainage network. This study provides an example of how mire formation and peat accumulation can create broad-scale heterogeneity in nutrient supply and demand across boreal landscapes. This mismatch allows for hydrologic losses of reactive N that are independent of annual plant demand and potentially important to receiving lakes and streams.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
nitrogen, mire, peatlands, peat, boreal, watershed biogeochemistry
National Category
Environmental Sciences Ecology
Identifiers
urn:nbn:se:umu:diva-145387 (URN)10.1007/s10021-017-0133-0 (DOI)000425004400003 ()
Available from: 2018-03-01 Created: 2018-03-01 Last updated: 2018-06-09Bibliographically approved
Laudon, H. & Sponseller, R. A. (2018). How landscape organization and scale shape catchment hydrology and biogeochemistry: insights from a long-term catchment study. WIREs Water, 5(2), Article ID e1265.
Open this publication in new window or tab >>How landscape organization and scale shape catchment hydrology and biogeochemistry: insights from a long-term catchment study
2018 (English)In: WIREs Water, ISSN 0935-879X, E-ISSN 2049-1948, Vol. 5, no 2, article id e1265Article, review/survey (Refereed) Published
Abstract [en]

Catchment science plays a critical role in the protection of water resources in the face of ongoing changes in climate, long-range transport of air pollutants, and land use. Addressing these challenges, however, requires improved understanding of how, when, and where changes in water quantity and quality occur within river networks. To reach these goals, we must recognize how different catchment features are organized to regulate surface chemistry at multiple scales, from processes controlling headwaters, to the downstream mixing of water from multiple landscape sources and deep aquifers. Here we synthesize 30-years of hydrological and biogeochemical research from the Krycklan catchment study (KCS) in northern Sweden to demonstrate the benefits of coupling long-term monitoring with multi-scale research to advance our understanding of catchment functioning across space and time. We show that the regulation of hydrological and biogeochemical patterns in the KCS can be decomposed into four, hierarchically structured landscape features that include: (1) transmissivity and reactivity of dominant source layers within riparian soils, (2) spatial arrangement of groundwater input zones that govern water and solute fluxes at reach- to segment-scales, (3) landscape scale heterogeneity (forests, mires, and lakes) that generates unique biogeochemical signals downstream, and (4) broad-scale mixing of surface streams with deep groundwater contributions. While this set of features are perhaps specific to the study region, analogous hierarchical controls are likely to be widespread. Resolving these scale dependent processes is important for predicting how, when, and where different environmental changes may influence patterns of surface water chemistry within river networks. (C) 2017 Wiley Periodicals, Inc.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
National Category
Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:umu:diva-146152 (URN)10.1002/wat2.1265 (DOI)000425438800001 ()
Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2018-06-09Bibliographically approved
Hasselquist, E. M., Lidberg, W., Sponseller, R. A., Agren, A. & Laudon, H. (2018). Identifying and assessing the potential hydrological function of past artificial forest drainage. Ambio, 47(5), 546-556
Open this publication in new window or tab >>Identifying and assessing the potential hydrological function of past artificial forest drainage
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2018 (English)In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 47, no 5, p. 546-556Article in journal (Refereed) Published
Abstract [en]

Drainage of forested wetlands for increased timber production has profoundly altered the hydrology and water quality of their downstream waterways. Some ditches need network maintenance (DNM), but potential positive effects on tree productivity must be balanced against environmental impacts. Currently, no clear guidelines exist for DNM that strike this balance. Our study helps begin to prioritise DNM by: (1) quantifying ditches by soil type in the 68 km(2) Krycklan Catchment Study in northern Sweden and (2) using upslope catchment area algorithms on new high-resolution digital elevation models to determine their likelihood to drain water. Ditches nearly doubled the size of the stream network (178-327 km) and 17% of ditches occurred on well-draining sedimentary soils, presumably making DNM unwarranted. Modelling results suggest that 25-50% of ditches may never support flow. With new laser scanning technology, simple mapping and modelling methods can locate ditches and model their function, facilitating efforts to balance DNM with environmental impacts.

Keywords
DEM, Flow accumulation model, Hydrology, LiDAR, Peatland, Terrain-based prediction
National Category
Forest Science
Identifiers
urn:nbn:se:umu:diva-150814 (URN)10.1007/s13280-017-0984-9 (DOI)000440734800003 ()29098602 (PubMedID)
Available from: 2018-08-20 Created: 2018-08-20 Last updated: 2018-08-20Bibliographically approved
Projects
Integrating stream energy budgets and consumer food webs in changing arctic streams [2018-05978_VR]; Umeå UniversityExploring novel connections between land and water: linking belowground carbon production by trees to stream ecosystem dynamics [2018-04395_VR]; Umeå University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5758-2705

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