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Inorganic nitrogen and microbial biomass dynamics before and during spring snowmelt

Biogeochemistry

By:
, ,
DOI: 10.1023/A:1005947511910

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Abstract

Recent work in seasonally snow covered ecosystems has identified thawed soil and high levels of heterotrophic activity throughout the winter under consistent snow cover. We performed measurements during the winter of 1994 to determine how the depth and timing of seasonal snow cover affect soil microbial populations, surface water NO3/- loss during snowmelt, and plant N availability early in the growing season. Soil under early accumulating, consistent snow cover remained thawed during most of the winter and both microbial biomass and soil inorganic N pools gradually increased under the snowpack. At the initiation of snowmelt, microbial biomass N pools increased from 3.0 to 5.9 g N m-2, concurrent with a decrease in soil inorganic N pools. During the latter stages of snowmelt, microbial biomass N pools decreased sharply without a concurrent increase in inorganic N pools or significant leaching losses. In contrast, soil under inconsistent snow cover remained frozen during most of the winter. During snowmelt, microbial biomass initially increased from 1.7 to 3.1 g N m-2 and then decreased as sites became snow-free. In contrast to smaller pool sizes, NO3/-export during snowmelt from the inconsistent snow cover sites of 1.14 (??0.511) g N m-2 was significantly greater (p < 0.001) than the 0.27 (??0.16) g N m-2 exported from sites with consistent snow cover. These data suggest that microbial biomass in consistently snow-covered soil provides a significant buffer limiting the export of inorganic N to surface water during snowmelt. However, this buffer is very sensitive to changes in snowpack regime. Therefore, interannual variability in the timing and depth of snowpack accumulation may explain the year to year variability in inorganic N concentrations in surface water these ecosystems.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Inorganic nitrogen and microbial biomass dynamics before and during spring snowmelt
Series title:
Biogeochemistry
DOI:
10.1023/A:1005947511910
Volume
43
Issue:
1
Year Published:
1998
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Biogeochemistry
First page:
1
Last page:
15
Number of Pages:
15