Influences of Hillslope Biogeochemistry on Anaerobic Soil Organic Matter Decomposition in a Tundra Watershed
We investigated rates and controls on greenhouse gas (CO2 and CH4) production in two contrasting water-saturated tundra soils within a permafrost-affected watershed near Nome, Alaska, United States. Three years of field sample analysis have shown that soil from a fen-like area in the toeslope of the...
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ftcdlib:oai:escholarship.org/ark:/13030/qt5gg1k6zm 2023-05-15T15:10:31+02:00 Influences of Hillslope Biogeochemistry on Anaerobic Soil Organic Matter Decomposition in a Tundra Watershed Philben, M Taş, N Chen, H Wullschleger, SD Kholodov, A Graham, DE Gu, B 2020-07-01 application/pdf https://escholarship.org/uc/item/5gg1k6zm unknown eScholarship, University of California qt5gg1k6zm https://escholarship.org/uc/item/5gg1k6zm public Journal of Geophysical Research: Biogeosciences, vol 125, iss 7 methane Arctic permafrost hillslope biogeochemistry microbial nitrogen limitation Geophysics article 2020 ftcdlib 2021-06-28T17:07:35Z We investigated rates and controls on greenhouse gas (CO2 and CH4) production in two contrasting water-saturated tundra soils within a permafrost-affected watershed near Nome, Alaska, United States. Three years of field sample analysis have shown that soil from a fen-like area in the toeslope of the watershed had higher pH and higher porewater ion concentrations than soil collected from a bog-like peat plateau at the top of the hillslope. The influence of these contrasting geochemical and topographic environments on CO2 and CH4 production was tested in soil microcosms by incubating both the organic- and mineral-layer soils anaerobically for 55days. Nitrogen (as NH4Cl) was added to half of the microcosms to test potential effects of N limitation on microbial greenhouse gas production. We found that the organic toeslope soils produced more CO2 and CH4, fueled by higher pH and higher concentrations of water-extractable organic C (WEOC). Our results also indicate N limitation on CO2 production in the peat plateau soils but not the toeslope soils. Together these results suggest that the weathering and leaching of ions and nutrients from tundra hillslopes can increase the rate of anaerobic soil organic matter decomposition in downslope soils by (1) increasing the pH of soil porewater; (2) providing bioavailable WEOC and fermentation products such as acetate; and (3) relieving microbial N limitation through nutrient runoff. We conclude that the soil geochemistry as mediated by landscape position is an important factor influencing the rate and magnitude of greenhouse gas production in tundra soils. Article in Journal/Newspaper Arctic Nome Peat Peat plateau permafrost Tundra Alaska University of California: eScholarship Arctic |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
methane Arctic permafrost hillslope biogeochemistry microbial nitrogen limitation Geophysics |
spellingShingle |
methane Arctic permafrost hillslope biogeochemistry microbial nitrogen limitation Geophysics Philben, M Taş, N Chen, H Wullschleger, SD Kholodov, A Graham, DE Gu, B Influences of Hillslope Biogeochemistry on Anaerobic Soil Organic Matter Decomposition in a Tundra Watershed |
topic_facet |
methane Arctic permafrost hillslope biogeochemistry microbial nitrogen limitation Geophysics |
description |
We investigated rates and controls on greenhouse gas (CO2 and CH4) production in two contrasting water-saturated tundra soils within a permafrost-affected watershed near Nome, Alaska, United States. Three years of field sample analysis have shown that soil from a fen-like area in the toeslope of the watershed had higher pH and higher porewater ion concentrations than soil collected from a bog-like peat plateau at the top of the hillslope. The influence of these contrasting geochemical and topographic environments on CO2 and CH4 production was tested in soil microcosms by incubating both the organic- and mineral-layer soils anaerobically for 55days. Nitrogen (as NH4Cl) was added to half of the microcosms to test potential effects of N limitation on microbial greenhouse gas production. We found that the organic toeslope soils produced more CO2 and CH4, fueled by higher pH and higher concentrations of water-extractable organic C (WEOC). Our results also indicate N limitation on CO2 production in the peat plateau soils but not the toeslope soils. Together these results suggest that the weathering and leaching of ions and nutrients from tundra hillslopes can increase the rate of anaerobic soil organic matter decomposition in downslope soils by (1) increasing the pH of soil porewater; (2) providing bioavailable WEOC and fermentation products such as acetate; and (3) relieving microbial N limitation through nutrient runoff. We conclude that the soil geochemistry as mediated by landscape position is an important factor influencing the rate and magnitude of greenhouse gas production in tundra soils. |
format |
Article in Journal/Newspaper |
author |
Philben, M Taş, N Chen, H Wullschleger, SD Kholodov, A Graham, DE Gu, B |
author_facet |
Philben, M Taş, N Chen, H Wullschleger, SD Kholodov, A Graham, DE Gu, B |
author_sort |
Philben, M |
title |
Influences of Hillslope Biogeochemistry on Anaerobic Soil Organic Matter Decomposition in a Tundra Watershed |
title_short |
Influences of Hillslope Biogeochemistry on Anaerobic Soil Organic Matter Decomposition in a Tundra Watershed |
title_full |
Influences of Hillslope Biogeochemistry on Anaerobic Soil Organic Matter Decomposition in a Tundra Watershed |
title_fullStr |
Influences of Hillslope Biogeochemistry on Anaerobic Soil Organic Matter Decomposition in a Tundra Watershed |
title_full_unstemmed |
Influences of Hillslope Biogeochemistry on Anaerobic Soil Organic Matter Decomposition in a Tundra Watershed |
title_sort |
influences of hillslope biogeochemistry on anaerobic soil organic matter decomposition in a tundra watershed |
publisher |
eScholarship, University of California |
publishDate |
2020 |
url |
https://escholarship.org/uc/item/5gg1k6zm |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Nome Peat Peat plateau permafrost Tundra Alaska |
genre_facet |
Arctic Nome Peat Peat plateau permafrost Tundra Alaska |
op_source |
Journal of Geophysical Research: Biogeosciences, vol 125, iss 7 |
op_relation |
qt5gg1k6zm https://escholarship.org/uc/item/5gg1k6zm |
op_rights |
public |
_version_ |
1766341537399046144 |