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Johanna Stadmark

Johanna Stadmark

Researcher

Johanna Stadmark

Amorphous silica pools in permafrost soils of the Central Canadian Arctic and the potential impact of climate change

Author

  • Hanna Alfredsson
  • G. Hugelius
  • Wim Clymans
  • Johanna Stadmark
  • P. Kuhry
  • Daniel Conley

Summary, in English

We investigated the distribution, storage and landscape partitioning of soil amorphous silica (ASi) in a central Canadian region dominated by tundra and peatlands to provide a first estimate of the amount of ASi stored in Arctic permafrost ecosystems. We hypothesize that, similar to soil organic matter, Arctic soils store large amounts of ASi which may be affected by projected climate changes and associated changes in permafrost regimes. Average soil ASi storage (top 1 m) ranged between 9600 and 83,500 kg SiO2 ha(-1) among different land-cover types. Lichen tundra contained the lowest amounts of ASi while no significant differences were found in ASi storage among other land-cover types. Clear differences were observed between ASi storage allocated into the top organic versus the mineral horizon of soils. Bog peatlands, fen peatlands and wet shrub tundra stored between 7090 and 45,400 kg SiO2 ha(-1) in the top organic horizon, while the corresponding storage in lichen tundra, moist shrub- and dry shrub tundra only amounted to 1500-1760 kg SiO2 ha(-1). Diatoms and phytoliths are important components of ASi storage in the top organic horizon of peatlands and shrub tundra systems, while it appears to be a negligible component of ASi storage in the mineral horizon of shrub tundra classes. ASi concentrations decrease with depth in the soil profile for fen peatlands and all shrub tundra classes, suggesting recycling of ASi, whereas bog peatlands appeared to act as sinks retaining stored ASi on millennial time scales. Our results provide a conceptual framework to assess the potential effects of climate change impacts on terrestrial Si cycling in the Arctic. We believe that ASi stored in peatlands are particularly sensitive to climate change, because a larger fraction of the ASi pool is stored in perennially frozen ground compared to shrub tundra systems. A likely outcome of climate warming and permafrost thaw could be mobilization of previously frozen ASi, altered soil storage of biogenically derived ASi and an increased Si flux to the Arctic Ocean.

Department/s

  • Quaternary Sciences
  • BECC - Biodiversity and Ecosystem services in a Changing Climate

Publishing year

2015

Language

English

Pages

441-459

Publication/Series

Biogeochemistry

Volume

124

Issue

1-3

Document type

Journal article

Publisher

Springer

Topic

  • Geology

Keywords

  • Amorphous silica
  • Arctic
  • Climate change
  • Peatlands
  • Permafrost
  • Terrestrial Si cycle
  • Tundra

Status

Published

ISBN/ISSN/Other

  • ISSN: 1573-515X