Title Soil biogeochemistry during the early spring in low Arctic mesic tundra and the impacts of deepened snow and enhanced nitrogen availability
Author Buckeridge, K.M.; Cen, Y.; Layzell, D.B.; Grogan, P.
Author Affil Buckeridge, K.M., Queen's University, Department of Biology, Kingston, ON, Canada. Other: University of Calgary, Canada
Source Biogeochemistry (Dordrecht), 99(1-3), p.127-141, . Publisher: Springer, Dordrecht - Boston - Lancaster, International. ISSN: 0168- 2563
Publication Date July 2010
Notes In English. 63 refs. GeoRef Acc. No: 310431
Index Terms precipitation (meteorology); biomass; chemical analysis; climate; climatic change; ecology; ecosystems; environmental effects; freezing; geochemistry; hummocks; hydrocarbons; snow; soils; soil analysis; soil chemistry; statistical analysis; thawing; tundra; Arctic region; Canada-- Northwest Territories; aliphatic hydrocarbons; alkanes; atmospheric precipitation; bioavailability; biochemistry; Canada; carbon dioxide; chromatograms; climate change; cycles; Daring Lake; gas chromatograms; leachate; methane; nitrogen; Northwest Territories; organic compounds; seasonal variations; soil gases; total organic carbon; Western Canada
Abstract Air temperature freeze-thaw cycles often occur during the early spring period directly after snowmelt and before budbreak in low arctic tundra. This early spring period may be associated with nitrogen (N) and carbon (C) loss from soils as leachate or as trace gases, due to the detrimental impact of soil freeze-thaw cycles and a developing active layer on soil microorganisms. We measured soil and microbial pools of C and N in early spring during a period of fluctuating air temperature (ranging from -4 to +10C) and in midsummer, in low arctic birch hummock tundra. In addition we measured N2O, CH4 and CO2 production in the early spring. All of these biogeochemical variables were also measured in long-term snowfence (deepened snow) and N-addition plots to characterize climate-change related controls on these variables. Microbial and soil solution pools of C and N, and trace gas production varied among the five early spring sample dates, but only marginally and no more than among sample dates in midsummer. N- addition greatly elevated N2O fluxes, indicating that although denitrifiers were present their activity during early spring was strongly limited by N-availability, but otherwise trace gas production was very low in early spring. The later thaw, warmer winter and colder spring soil temperatures resulting from deepened snow did not significantly alter N pools or rates in early spring. Together, our results indicate strong stability in microbial and soil solution C and N pool sizes in the early spring period just after snowmelt when soil temperatures are close to 0C (-1.5 to +5C). A review of annual temperature records from this and other sites suggests that soil freeze-thaw cycles are probably infrequent in mesic tundra in early spring. We suggest that future studies concerned with temperature controls on soil and microbial biogeochemistry should focus not on soil freeze-thaw cycles per se, but on the rapid and often stepped increases in soil temperature that occur under the thawing snowpack. Copyright 2009 Springer Science+Business Media B.V.
URL http://hdl.handle.net/10.1007/s10533-009-9396-7
Publication Type journal article
Record ID 65007166