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Tree line advance reduces mixing and oxygen concentrations in arctic-alpine lakes through wind sheltering and organic carbon supply

Klaus, Marcus and Karlsson, Jan and Seekell, David (2021). Tree line advance reduces mixing and oxygen concentrations in arctic-alpine lakes through wind sheltering and organic carbon supply. Global Change Biology. 27 , 4238-4253
[Research article]

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Abstract

Oxygen depletion in lake bottom waters has adverse impacts on ecosystem health including decreased water quality from release of nutrients and reduced substances from sediments, and the reduction of fish growth and reproduction. Depletion occurs when oxygen is consumed during decomposition of organic matter, and oxygen replenishment is limited by water column stratification. Arctic-alpine lakes are often well mixed and oxygenated, but rapid climate change in these regions is an important driver of shifts in catchment vegetation that could affect the mixing and oxygen dynamics of lakes. Here, we analyze high-resolution time series of dissolved oxygen concentration and temperature profiles in 40 Swedish arctic-alpine lakes across the tree line ecotone. The lakes stratified for 1-125 days, and during stratification, near-bottom dissolved oxygen concentrations changed by -0.20 to +0.15 mg L-1 day(-1), resulting in final concentrations of 1.1-15.5 mg L-1 at the end of the longest stratification period. Structural equation modeling revealed that lakes with taller shoreline vegetation relative to lake area had higher dissolved organic carbon concentrations and oxygen consumption rates, but also lower wind speeds and longer stratification periods, and ultimately, lower near-bottom dissolved oxygen concentrations. We use an index of shoreline canopy height and lake area to predict variations among our study lakes in near-bottom dissolved oxygen concentrations at the end of the longest stratification period (R-2 = 0.41). Upscaling this relationship to 8392 Swedish arctic-alpine lakes revealed that near-bottom dissolved oxygen concentrations drop below 3, 5, and 7 mg L-1 in 15%, 32%, and 53% of the lakes and that this proportion is sensitive (5%-22%, 13%-45%, and 29%-69%) to hypothetical tree line shifts observed in the past century or reconstructed for the Holocene (+/- 200 m elevation; +/- 0.5 degrees latitude). Assuming space-for-time substitution, we predict that tree line advance will decrease near-bottom dissolved oxygen concentrations in many arctic-alpine lakes.

Authors/Creators:Klaus, Marcus and Karlsson, Jan and Seekell, David
Title:Tree line advance reduces mixing and oxygen concentrations in arctic-alpine lakes through wind sheltering and organic carbon supply
Series Name/Journal:Global Change Biology
Year of publishing :2021
Volume:27
Page range:4238-4253
Number of Pages:16
Publisher:WILEY
ISSN:1354-1013
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution-No Derivative Works 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
Keywords:dissolved organic carbon, environmental change, forest-tundra ecotone, hypoxia, lake ecosystem, lake stratification, thermal structure, wind speed
URN:NBN:urn:nbn:se:slu:epsilon-p-112230
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-112230
Additional ID:
Type of IDID
DOI10.1111/gcb.15660
Web of Science (WoS)000651544700001
ID Code:24981
Faculty:S - Faculty of Forest Sciences
Department:(S) > Dept. of Forest Ecology and Management
Deposited By: SLUpub Connector
Deposited On:23 Aug 2021 09:25
Metadata Last Modified:23 Aug 2021 09:31

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