Open Access
Increased snow depth affects microbial activity and nitrogen mineralization in two Arctic tundra communities - eScholarship
Josh P Schimel,C Bilbrough,J A Welker +2 more
- Vol. 36, Iss: 2, pp 217-227
TLDR
In this paper, the authors used intact core incubations sampled periodically through the winter and following growing season to measure net N mineralization and nitrification in dry heath and in moist tussock tundra under ambient and experimentally increased snow depths.Abstract:
Microbial activity in Arctic tundra ecosystems continues through the winter and is an important component of the annual C budget. This activity is sensitive to climatic variation, particularly snow depth because that regulates soil temperature. The influence of winter conditions on soil N cycling is poorly understood. In this study, we used intact core incubations sampled periodically through the winter and following growing season to measure net N mineralization and nitrification in dry heath and in moist tussock tundra under ambient and experimentally increased snow depths (by use of a snowfence). In dry heath, we sampled soils under Dryas octopetela or Arctostaphylos alpine, while in tussock tundra, we sampled Eriophorum vaginatum tussocks and Sphagnum dominated areas between tussocks. Our objectives were to: (1) examine how different winter snow regimes influenced year-round N dynamics in the two tundra types, and (2) evaluate how these responses are affected by dominant species present in each system. In tussock tundra, soils with increased winter snow cover had high net N mineralization rates during the fall and winter, followed by immobilization during thaw. In contrast, N mineralization only occurred during the autumn in soils with ambient snow cover. During the growing season when N immobilization dominated in areas with ambient snow cover, soils with increased winter snow cover had positive net mineralization and nitrification rates. In dry heath tundra, soils with increased snow depth had high late winter net N mineralization rates, but these rates were: (a) comparable to early winter rates in soils under Arctostaphylos plants with ambient snow cover; (b) greater in soils under Arctostaphylos plants than in soils under Dryas plants; and (c) less than the rates found in tussock tundra. Our findings suggest under ambient snow conditions, low soil temperatures limit soil N mineralization, but that deeper snow conditions with the associated warmer winter soil temperatures dramatically increase over-winter N mineralization and thereby alter the amount and timing of plant-available N in tundra ecosystems. (C) 2003 Elsevier Ltd. All rights reserved.read more
Citations
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Journal ArticleDOI
Microbial stress‐response physiology and its implications for ecosystem function
TL;DR: It is suggested that more effectively integrating microbial ecology into ecosystem ecology will require a more complete integration of microbial physiological ecology, population biology, and process ecology.
Journal ArticleDOI
Shrub expansion in tundra ecosystems: dynamics, impacts and research priorities
Isla H. Myers-Smith,Isla H. Myers-Smith,Bruce C. Forbes,Martin Wilmking,Martin Hallinger,Trevor C. Lantz,Daan Blok,Ken D. Tape,Marc Macias-Fauria,Ute Sass-Klaassen,Esther Lévesque,Stéphane Boudreau,Pascale Ropars,Luise Hermanutz,Andrew J. Trant,Laura Siegwart Collier,Stef Weijers,Jelte Rozema,Shelly A. Rayback,Niels Martin Schmidt,Gabriela Schaepman-Strub,Sonja Wipf,Christian Rixen,Cécile B. Ménard,Susanna Venn,Scott J. Goetz,Laia Andreu-Hayles,Sarah C. Elmendorf,Virve Ravolainen,Jeffrey M. Welker,Paul Grogan,Howard E. Epstein,David S. Hik +32 more
TL;DR: This article used repeat photography, long-term ecological monitoring and dendrochronology to document shrub expansion in arctic, high-latitude and alpine tundra.
Journal ArticleDOI
Winter Biological Processes Could Help Convert Arctic Tundra to Shrubland
Matthew Sturm,Josh Schimel,Gary J. Michaelson,Jeffrey M. Welker,Steven F. Oberbauer,Glen E. Liston,Jace T. Fahnestock,Vladimir E. Romanovsky +7 more
TL;DR: Evidence suggests that winter biological processes are contributing to this conversion of tundra to shrubland through a positive feedback that involves the snow-holding capacity of shrubs, the insulating properties of snow, and soil layer that has a high water content because it overlies nearly impermeable permafrost.
Journal ArticleDOI
Do freeze-thaw events enhance C and N losses from soils of different ecosystems? A review
Egbert Matzner,Werner Borken +1 more
TL;DR: In this article, the effects of freezing temperature and frequency, the differences between arable soils and soils under natural vegetation, and the hypothesis that freeze-thaw events lead to significant C and N losses from soils at the annual scale.
Journal ArticleDOI
Ecosystem feedbacks and cascade processes: understanding their role in the responses of Arctic and alpine ecosystems to environmental change
Philip A. Wookey,Rien Aerts,Richard D. Bardgett,Florence Baptist,Kari Anne Bråthen,Johannes H. C. Cornelissen,Laura Gough,Iain P. Hartley,David Hopkins,David Hopkins,Sandra Lavorel,Gaius R. Shaver +11 more
TL;DR: In this article, the effects of changes in species distributions and dominances on key ecosystem processes and properties are considered, based upon best estimates of the trajectories of key transformations, their magnitude and rates of change.
References
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Book
Principles of Terrestrial Ecosystem Ecology
TL;DR: In this paper, the Ecosystem Concept is used to describe the Earth's Climate System and Geology and Soils, and the ecosystem concept is used for managing and sustaining ecosystems.
Journal ArticleDOI
Microbial stress‐response physiology and its implications for ecosystem function
TL;DR: It is suggested that more effectively integrating microbial ecology into ecosystem ecology will require a more complete integration of microbial physiological ecology, population biology, and process ecology.
Journal ArticleDOI
Responses of Arctic Tundra to Experimental and Observed Changes in Climate
TL;DR: In this article, the authors manipulated light, temperature, and nutrients in moist tussock tundra near Toolik Lake, Alaska to determine how global changes in these parameters might affect community and ecosystem processes.
Journal ArticleDOI
Shrub expansion in tundra ecosystems: dynamics, impacts and research priorities
Isla H. Myers-Smith,Isla H. Myers-Smith,Bruce C. Forbes,Martin Wilmking,Martin Hallinger,Trevor C. Lantz,Daan Blok,Ken D. Tape,Marc Macias-Fauria,Ute Sass-Klaassen,Esther Lévesque,Stéphane Boudreau,Pascale Ropars,Luise Hermanutz,Andrew J. Trant,Laura Siegwart Collier,Stef Weijers,Jelte Rozema,Shelly A. Rayback,Niels Martin Schmidt,Gabriela Schaepman-Strub,Sonja Wipf,Christian Rixen,Cécile B. Ménard,Susanna Venn,Scott J. Goetz,Laia Andreu-Hayles,Sarah C. Elmendorf,Virve Ravolainen,Jeffrey M. Welker,Paul Grogan,Howard E. Epstein,David S. Hik +32 more
TL;DR: This article used repeat photography, long-term ecological monitoring and dendrochronology to document shrub expansion in arctic, high-latitude and alpine tundra.
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