Blackburn, Meredith
(2018).
In search of control points: A study on the interaction of hydrological fluxes and nitrogen in the boreal landscape.
Diss. (sammanfattning/summary)
Umeå :
Sveriges lantbruksuniv.,
Acta Universitatis Agriculturae Sueciae, 1652-6880
; 2018:2
ISBN 978-91-7760- 144-9
eISBN 978-91-7760-145-6
[Doctoral thesis]
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Abstract
Nitrogen (N) export from terrestrial ecosystems is strongly influenced by hydrological flux, but losses of reactive N forms through surface waters are generally thought to be under strong biological control. However, losses from terrestrial ecosystems may be fostered by catchment processes that allow N to circumvent biological uptake. The aim of my research was to investigate how boreal landscape attributes interact with hydrological forcing to regulate N delivery to streams. I explored these controls through detailed study of key land-water interfaces, in combination with broader assessments of N concentration and export in the Krycklan Catchment Study (KCS), located in northern Sweden. I found, contrary to the prevailing view, forest riparian zones represented a net source of dissolved organic N (DON) and dissolved inorganic N (DIN) to streams. This pattern is connected to organic-rich riparian soils that promote local N production, potentially decoupling stream N exports from upland forest processes. Mires also acted as important N sources as reduced N in deep peat layers was delivered to streams through preferential flowpaths. At network scales, unique headwater biogeochemical patterns became more synchronous downstream, as mire, forest, and lake signals mixed. Nonetheless, mire and wet riparian areas emerged as important explanatory variables for stream N composition and concentration across the KCS. Finally, the relative importance of hydrological flux as the driver of N export in this system differed according to N form, the temporal scale considered, and catchment structure. DON formed close and consistent relationships with discharge among sites, years, and seasons, while DIN export was more weakly and variably related to flow. Still, surprisingly strong flow-controlled DIN export was observed during snow-free seasons, highlighting the importance of local, riparian N sources. Overall, my results suggest that long term peat accumulation – both in riparian zones and in mires – has created control points that regulate N losses through different mechanisms. The strong influence of these patches may overwhelm the detection of upland forest influences on N export in relatively pristine boreal landscapes.
Authors/Creators: | Blackburn, Meredith | ||||||||||
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Title: | In search of control points: A study on the interaction of hydrological fluxes and nitrogen in the boreal landscape | ||||||||||
Series/Journal: | Acta Universitatis Agriculturae Sueciae (1652-6880) | ||||||||||
Year of publishing : | January 2018 | ||||||||||
Depositing date: | 3 January 2018 | ||||||||||
Number: | 2018:2 | ||||||||||
Number of Pages: | 44 | ||||||||||
Papers/manuscripts: |
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Place of Publication: | Umeå | ||||||||||
Publisher: | Department of Forest Ecology and Management,Swedish University of Agricultural Sciences | ||||||||||
ISBN for printed version: | 978-91-7760- 144-9 | ||||||||||
ISBN for electronic version: | 978-91-7760-145-6 | ||||||||||
ISSN: | 1652-6880 | ||||||||||
Language: | English | ||||||||||
Additional Information: | Main funding split 50/50 between projects: ForWater and NiCAF both Formas | ||||||||||
Publication Type: | Doctoral thesis | ||||||||||
Full Text Status: | Public | ||||||||||
Agris subject categories.: | P Natural resources > P10 Water resources and management | ||||||||||
Subjects: | (A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Geosciences, Multidisciplinary (A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Geochemistry (A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Oceanography, Hydrology, Water Resources (A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology (A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science | ||||||||||
Agrovoc terms: | boreal forests, nitrogen cycle, rivers, riparian zones, organic nitrogen compounds, terraces, peatlands, bogs, nitrogen fixation, nitrate | ||||||||||
Keywords: | nitrogen, disolved organic nitrogen, Ammonium, nitrate, riparian zone, mire, forest, stream, boreal, control point, hot spot | ||||||||||
URN:NBN: | urn:nbn:se:slu:epsilon-e-4596 | ||||||||||
Permanent URL: | http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-4596 | ||||||||||
ID Code: | 14932 | ||||||||||
Faculty: | S - Faculty of Forest Sciences | ||||||||||
Department: | (S) > Dept. of Forest Ecology and Management | ||||||||||
External funders: | FORMAS | ||||||||||
Deposited By: | Meredith Blackburn | ||||||||||
Deposited On: | 09 Jan 2018 10:54 | ||||||||||
Metadata Last Modified: | 09 Sep 2020 14:17 |
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