| 1. |
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| 2. |
- Bergknut, Magnus, et al.
(författare)
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Modelling the fate of hydrophobic organic contaminants in a boreal forest catchment : a cross disciplinary approach to assessing diffuse pollution to surface waters
- 2010
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 158:9, s. 2964-2969
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Tidskriftsartikel (refereegranskat)abstract
- The fate of hydrophobic organic compounds (HOCs) in soils and waters in a northern boreal catchment was explored through the development of a chemical fate model in a well-characterised catchment system dominated by two land types: forest and mire. Input was based solely on atmospheric deposition, dominated by accumulation in the winter snowpack. Release from soils was governed by the HOC concentration in soil, the soil organic carbon fraction and soil-water DOC content. The modelled export of selected HOCs in surface waters ranged between 11 and 250ng day(-1) during the snow covered period, compared to 200 and 9600ng/d during snow-melt; highlighting the importance of the snow pack as a source of these chemicals. The predicted levels of HOCs in surface water were in reasonable agreement to a limited set of measured values, although the model tended to over predict concentrations of HOCs for the forested sub-catchment, by over an order of magnitude in the case of hexachlorobenzene and PCB 180. This possibly reflects both the heterogeneity of the forest soils and the complicated and changing hydrology experienced between the different seasons.
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| 3. |
- Haei, Mahsa, 1981-, et al.
(författare)
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Cold winter soils enhance dissolved organic carbon concentrations in soil and stream water
- 2010
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Ingår i: Geophysical Research Letters. - : American Geophysical Union. - 0094-8276 .- 1944-8007. ; 37, s. L08501-
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Tidskriftsartikel (refereegranskat)abstract
- Concentrations of dissolved organic carbon ([DOC]) have increased in lakes, streams and rivers across a large part of the northern hemisphere and raised an animated scientific debate about the underlying mechanisms. The lack of consensus about the role of climate in controlling the DOC trends highlights the need for understanding the regulation of surface water DOC. We found that longer and colder winters result in higher [DOC] in a boreal headwater stream during the subsequent snowmelt. In addition, prolonged soil frost increases the spring and summer [DOC] in the riparian soil water, which is a major contributor of stream water DOC in the studied area. We conclude that winter climatic conditions can play a substantial role in controlling stream [DOC] in ways not previously understood. These findings are especially important for northern latitude regions expected to be most affected by climate change. Citation: Haei, M., M. G. Oquist, I. Buffam, A. angstrom gren, P. Blomkvist, K. Bishop, M. Ottosson Lofvenius, and H. Laudon (2010), Cold winter soils enhance dissolved organic carbon concentrations in soil and st ream water, Geophys. Res. Lett., 37, L08501, doi: 10.1029/2010GL042821.
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| 4. |
- Kothawala, Dolly N., et al.
(författare)
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The relative influence of land cover, hydrology, and in-stream processing on the composition of dissolved organic matter in boreal streams
- 2015
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Ingår i: Journal of Geophysical Research - Biogeosciences. - 2169-8953 .- 2169-8961. ; 120:8, s. 1491-1505
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Tidskriftsartikel (refereegranskat)abstract
- Low-order boreal streams are particularly sensitive interfaces where dissolved organic matter (DOM) is transported from soils to inland waters. Disentangling the relative influence of key environmental factors suspected to influence stream water DOM composition is highly relevant to predicting the reactivity and fate of terrestrial DOM entering inland waters. Here we examined changes to DOM composition using absorbance and fluorescence, from 17 boreal streams ranging from first to fourth orders, over 14 months, including the rarely studied winter season, and two snowmelt periods (n = 836). We also analyzed soil pore water samples from three forest soil lysimeters to a depth of 70 cm (n = 60). Of five identified fluorescing parallel factor analysis components, two (C4 and C5) expressed a clear mire wetland or forest signature, providing distinct molecular markers of dominant land cover. In fact, land cover alone explained 49% of the variability in DOM composition. In contrast, seasonal fluctuations in hydrology only contributed to minor shifts (8%) in the composition of stream water DOM, while in-stream transformations to DOM composition were undetectable. These findings suggest that low-order boreal streams act as a passive pipe, since in-stream processing of DOM is restricted by short water residence times (6 h to 2 days). In addition, we demonstrated the sensitivity of optical approaches to distinguish between key terrestrial sources of DOM in the boreal landscape. By distinguishing the proportional leverage of key environmental controls on headwater stream DOM composition, we are better equipped to predict where and when key DOM transformations occur in the aquatic conduit.
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| 5. |
- Kuglerova, Lenka, et al.
(författare)
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Groundwater discharge creates hotspots of riparian plant species richness in a boreal forest stream network
- 2014
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Ingår i: Ecology. - : Ecological Society of America. - 0012-9658 .- 1939-9170. ; 95:3, s. 715-725
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Kuglerová, Lenka, et al.
(författare)
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Towards optimizing riparian buffer zones : Ecological and biogeochemical implications for forest management
- 2014
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Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 334, s. 74-84
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Tidskriftsartikel (refereegranskat)abstract
- Riparian forests (RFs) along streams and rivers in forested landscapes provide many ecosystem functions that are important for the biodiversity and biogeochemistry of both terrestrial and aquatic ecosystems. In riverine landscapes, many of these ecological and biogeochemical functions have been found to be maximized in riparian areas with discharge of upland-originating groundwater (GW). This ecological significance, and the fact that riparian areas with GW discharge are important sources of many chemical elements in streams and rivers, makes these places important hotspots in the landscape. The natural functioning of RFs is however threatened by poorly designed management practices, with forestry being one of the most important examples in timber producing regions. Logging operations in riparian, but also in adjoining upland forests, threaten to alter many riparian functions. This effect is accelerated in GW discharge hotspots because of their sensitive soils and the high connectivity with uphill areas. We thus argue that forestry practices should give higher consideration to riparian GW discharge areas, and we demonstrate how improved riparian buffer zone management can be incorporated into every-day forestry planning. We offer a practical tool for more optimized site-specific riparian buffer design by using model-derived high resolution maps with detailed information about wetness and soil–water flow paths within RFs. We describe how such site-specific riparian buffer management differs from fixed-width buffers, which are generally applied in today’s forestry, and address some risks connected to fixed-width buffer management. We conclude that site-specific riparian management, allowing wider buffers at GW discharge areas and more narrow buffers on sites of lower ecological significance (i.e. riparian sites without GW flow paths), would benefit a variety of ecosystem services, mitigate negative effects caused by forestry and create more variable and heterogeneous riparian corridors. Finally, we show examples of how the new forestry planning can be applied.
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| 7. |
- Larson, Johannes, et al.
(författare)
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Predicting soil moisture conditions across a heterogeneous boreal catchment using terrain indices
- 2022
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 26, s. 4837-4851
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Tidskriftsartikel (refereegranskat)abstract
- Soil moisture has important implications for drought and flooding forecasting, forest fire prediction and water supply management. However, mapping soil moisture has remained a scientific challenge due to forest canopy cover and small-scale variations in soil moisture conditions. When accurately scaled, terrain indices constitute a good candidate for modelling the spatial variation of soil moisture conditions in many landscapes. In this study, we evaluated seven different terrain indices at varying digital elevation model (DEM) resolutions and user-defined thresholds as well as two available soil moisture maps, using an extensive field dataset (398 plots) of soil moisture conditions registered in five classes from a survey covering a (68 km2) boreal landscape. We found that the variation in soil moisture conditions could be explained by terrain indices, and the best predictors within the studied landscape were the depth to water index (DTW) and a machine-learning-generated map. Furthermore, this study showed a large difference between terrain indices in the effects of changing DEM resolution and user-defined thresholds, which severely affected the performance of the predictions. For example, the commonly used topographic wetness index (TWI) performed best on a resolution of 16 m, while TWI calculated on DEM resolutions higher than 4 m gave inaccurate results. In contrast, depth to water (DTW) and elevation above stream (EAS) were more stable and performed best on 1–2 m DEM resolution. None of the terrain indices performed best on the highest DEM resolution of 0.5 m. In addition, this study highlights the challenges caused by heterogeneous soil types within the study area and shows the need of local knowledge when interpreting the modelled results. The results from this study clearly demonstrate that when using terrain indices to represent soil moisture conditions, modelled results need to be validated, as selecting an unsuitable DEM resolution or user-defined threshold can give ambiguous and even incorrect results.
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| 8. |
- Laudon, Hjalmar, et al.
(författare)
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Consequences of More Intensive Forestry for the Sustainable Management of Forest Soils and Waters
- 2011
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Ingår i: Forests. - : MDPI AG. - 1999-4907 .- 1999-4907. ; 2, s. 243-260
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Tidskriftsartikel (refereegranskat)abstract
- Additions of nutrients, faster growing tree varieties, more intense harvest practices, and a changing climate all have the potential to increase forest production in Sweden, thereby mitigating climate change through carbon sequestration and fossil fuel substitution. However, the effects of management strategies for increased biomass production on soil resources and water quality at landscape scales are inadequately understood. Key knowledge gaps also remain regarding the sustainability of shorter rotation periods and more intensive biomass harvests. This includes effects of fertilization on the long-term weathering and supply of base cations and the consequences of changing mineral availability for future forest production. Furthermore, because soils and surface waters are closely connected, management efforts in the terrestrial landscape will potentially have consequences for water quality and the ecology of streams, rivers, and lakes. Here, we review and discuss some of the most pertinent questions related to how increased forest biomass production in Sweden could affect soils and surface waters, and how contemporary forestry goals can be met while minimizing the loss of other ecosystem services. We suggest that the development of management plans to promote the sustainable use of soil resources and water quality, while maximizing biomass production, will require a holistic ecosystem approach that is placed within a broader landscape perspective.
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| 9. |
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| 10. |
- Laudon, Hjalmar, et al.
(författare)
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Northern landscapes in transition : Evidence, approach and ways forward using the Krycklan Catchment Study
- 2021
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Ingår i: Hydrological Processes. - : John Wiley & Sons. - 0885-6087 .- 1099-1085. ; 35:4
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Tidskriftsartikel (refereegranskat)abstract
- Improving our ability to detect changes in terrestrial and aquatic systems is a grand challenge in the environmental sciences. In a world experiencing increasingly rapid rates of climate change and ecosystem transformation, our ability to understand and predict how, when, where, and why changes occur is essential for adapting and mitigating human behaviours. In this context, long-term field research infrastructures have a fundamentally important role to play. For northern boreal landscapes, the Krycklan Catchment Study (KCS) has supported monitoring and research aimed at revealing these changes since it was initiated in 1980. Early studies focused on forest regeneration and microclimatic conditions, nutrient balances and forest hydrology, which included monitoring climate variables, water balance components, and stream water chemistry. The research infrastructure has expanded over the years to encompass a 6790 ha catchment, which currently includes 11 gauged streams, ca. 1000 soil lysimeters, 150 groundwater wells, >500 permanent forest inventory plots, and a 150 m tall tower (a combined ecosystem-atmosphere station of the ICOS, Integrated Carbon Observation System) for measurements of atmospheric gas concentrations and biosphere-atmosphere exchanges of carbon, water, and energy. In addition, the KCS has also been the focus of numerous high resolution multi-spectral LiDAR measurements and large scale experiments. This large collection of equipment and data generation supports a range of disciplinary studies, but more importantly fosters multi-, trans-, and interdisciplinary research opportunities. The KCS attracts a broad collection of scientists, including biogeochemists, ecologists, foresters, geologists, hydrologists, limnologists, soil scientists, and social scientists, all of whom bring their knowledge and experience to the site. The combination of long-term monitoring, shorter-term research projects, and large-scale experiments, including manipulations of climate and various forest management practices, has contributed much to our understanding of boreal landscape functioning, while also supporting the development of models and guidelines for research, policy, and management.
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