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Evaluating hillslope and riparian contributions to dissolved nitrogen (N) export from a boreal forest catchment

Blackburn, Meredith and Ledesma, Jose and Näsholm, Torgny and Laudon, Hjalmar and Sponseller, Ryan (2017). Evaluating hillslope and riparian contributions to dissolved nitrogen (N) export from a boreal forest catchment. Journal of geophysical research. 122:2, 324-339
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Official URL: http://dx.doi.org/10.1002/2016JG003535

Abstract

Catchment science has long held that the chemistry of small streams reflects the landscapes they drain. However, understanding the contribution of different landscape units to stream chemistry remains a challenge which frequently limits our understanding of export dynamics. For limiting nutrients such as nitrogen (N), an implicit assumption is that the most spatially extensive landscape units (e.g., uplands) act as the primary sources to surface waters, while near-stream zones function more often as sinks. These assumptions, based largely on studies in high-gradient systems or in regions with elevated inputs of anthropogenic N, may not apply to low-gradient, nutrient-poor, and peat-rich catchments characteristic of many northern ecosystems. We quantified patterns of N mobilization along a hillslope transect in a northern boreal catchment to assess the extent to which organic matter-rich riparian soils regulate the flux of N to streams. Contrary to the prevailing view of riparian functioning, we found that near-stream, organic soils supported concentrations and fluxes of ammonium (NH4+) and dissolved organic nitrogen that were much higher than the contributing upslope forest soils. These results suggest that stream N chemistry is connected to N mobilization and mineralization within the riparian zone rather than the wider landscape. Results further suggest that water table fluctuation in near-surface riparian soils may promote elevated rates of net N mineralization in these landscapes.

Authors/Creators:Blackburn, Meredith and Ledesma, Jose and Näsholm, Torgny and Laudon, Hjalmar and Sponseller, Ryan
Title:Evaluating hillslope and riparian contributions to dissolved nitrogen (N) export from a boreal forest catchment
Series/Journal:Journal of geophysical research (0148-0227)
Year of publishing :2017
Volume:122
Number:2
Page range:324-339
Number of Pages:16
Publisher:American Geophysical Union
ISSN:0148-0227
Language:English
Publication Type:Journal article
Refereed:Yes
Article category:Scientific peer reviewed
Version:Published version
Full Text Status:Public
Agris subject categories.:P Natural resources > P33 Soil chemistry and physics
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Environmental Sciences (social aspects to be 507)
(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Geosciences, Multidisciplinary
Agrovoc terms:watersheds, boreal, nitrogen
Keywords:riparian, organic nitrogen, groundwater, ammonium, boreal, watershed
URN:NBN:urn:nbn:se:slu:epsilon-e-4531
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-4531
Additional ID:
Type of IDID
Web of Science (WoS)000396130400004
ID Code:14715
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
S - Faculty of Forest Sciences
Department:(NL, NJ) > Dept. of Aquatic Sciences and Assessment
(S) > Dept. of Forest Ecology and Management
Deposited By: SLUpub Connector
Deposited On:06 Dec 2017 09:05
Metadata Last Modified:06 Dec 2017 09:05

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