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Changing Source-Transport Dynamics Drive Differential Browning Trends in a Boreal Stream Network

Fork, Megan L. and Sponseller, Ryan A. and Laudon, Hjalmar (2020). Changing Source-Transport Dynamics Drive Differential Browning Trends in a Boreal Stream Network. Water Resources Research. 56 , e2019WR026336 , 1-15
[Journal article]

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Abstract

Dissolved organic carbon (DOC) concentrations are increasing in freshwaters worldwide, with important implications for aquatic ecology, biogeochemistry, and ecosystem services. While multiple environmental changes may be responsible for these trends, predicting the occurrence and magnitude of "browning" and relating such trends to changes in DOC sources versus hydrologic transport remain key challenges. We analyzed long-term trends in DOC concentration from the two dominant landscape sources (riparian soils and mire peats) and receiving streams in a boreal catchment to evaluate how browning patterns relate to land cover and hydrology. Increases in stream DOC were widespread but not universal. Browning was most pronounced in small, forested streams, where trends corresponded to twofold to threefold increases in DOC production in riparian soils and increases in annual DOC export from a forested headwater. By contrast, DOC did not change in mire peats or streams draining catchments with high lake or mire cover, nor did we observe trends in DOC export from a mire-dominated headwater. The distinct long-term trends in DOC sources also altered concentration-discharge relationships, with a forested headwater shifting from transport-limited toward chemostasis, and a mire outlet stream shifting from chemostasis to source-limitated. Modified DOC supply to headwaters, together with altered seasonal hydrology and differences in the dominant water source along the stream network gave rise to predictable browning trends and consistent concentration-discharge relationships. Overall, our results show that the sources of DOC to boreal aquatic ecosystems are responding to environmental change in fundamentally different ways, with important consequences for browning along boreal stream networks.

Authors/Creators:Fork, Megan L. and Sponseller, Ryan A. and Laudon, Hjalmar
Title:Changing Source-Transport Dynamics Drive Differential Browning Trends in a Boreal Stream Network
Year of publishing :2020
Volume:56
Article number:e2019WR026336
Number of Pages:12
Publisher:AGU Journals
ISSN:0043-1397
Language:English
Publication Type:Journal article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution-Noncommercial 4.0
Full Text Status:Public
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 > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
Keywords:brownification, wetland, riparian, concentration-discharge, flux, DOC
URN:NBN:urn:nbn:se:slu:epsilon-p-107076
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-107076
Additional ID:
Type of IDID
DOI10.1029/2019WR026336
Web of Science (WoS)000535672800041
ID Code:17410
Faculty:S - Faculty of Forest Sciences
Department:(S) > Dept. of Forest Ecology and Management
Deposited By: SLUpub Connector
Deposited On:07 Sep 2020 09:37
Metadata Last Modified:07 Sep 2020 09:37

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