Nitrate and dissolved organic carbon mobilization in response to soil freezing variability

Reduced snowpack and associated increases in soil freezing severity resulting from winter climate change have the potential to disrupt carbon (C) and nitrogen (N) cycling in soils. We used a natural winter climate gradient based on elevation and aspect in a northern hardwood forest to examine the ef...

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Bibliographic Details
Published in:Biogeochemistry 2016-12, Vol.131 (1/2), p.35-47
Main Authors: Fuss, Colin B., Driscoll, Charles T., Groffman, Peter M., Campbell, John L., Christenson, Lynn M., Fahey, Timothy J., Fisk, Melany C., Mitchell, Myron J., Templer, Pamela H., Durán, Jorge, Morse, Jennifer L.
Format: Article
Language:English
Subjects:
Biogeosciences
Carbon
Climate change
Dissolved organic carbon
Earth and Environmental Science
Earth Sciences
Ecosystems
Elevation
Environmental Chemistry
Freezing
Growing season
Leaching
Life Sciences
Nitrates
Organic chemistry
ORIGINAL PAPERS
Snowpack
Soil depth
Soil solution
Soils
Surface runoff
Surface water
Thawing
Winter
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Summary:Reduced snowpack and associated increases in soil freezing severity resulting from winter climate change have the potential to disrupt carbon (C) and nitrogen (N) cycling in soils. We used a natural winter climate gradient based on elevation and aspect in a northern hardwood forest to examine the effects of variability in soil freezing depth, duration, and frequency on the mobilization of dissolved organic carbon (DOC) and nitrate (NO₃⁻) in soils over the course of 2 years. During a winter with a relatively thin snowpack, soils at lower elevation sites experienced greater freezing and especially variable freeze/thaw cycles, which in turn led to greater leaching of DOC from the organic horizon during the following growing season. In contrast to several previous field manipulation studies, we did not find changes in soil solution NO₃⁻ concentrations related to soil freezing variables. Our results are consistent with a soil matrix disturbance from freezing and thawing which increases leachable C. These results build upon previous laboratory experiments and field manipulations that found differing responses of DOC and NO₃⁻ following soil freezing, suggesting that mobilization of labile C may suppress NO₃⁻ losses through microbial immobilization of N. This research highlights the importance of studying natural variation in winter climate and soil freezing and how they impact soil C and N retention, with implications for surface water runoff quality.
ISSN:0168-2563
1573-515X
DOI:10.1007/s10533-016-0262-0