Snowpack Controls on Nitrogen Cycling
and Export in Seasonally Snow-Covered Catchments
Paul D. Brooks1 and Mark W. Williams2
Here we provide an overview of current research activities on nitrogen (N) cycling in high-eleva-
tion catchments of the Colorado Front Range. We then use this information to develop a conceptual
model of how snow cover controls subnivial (below snowpack) microbial processes and N leachate
from the snow/soil interface to surface waters. The duration of snow cover is divided into four
snowpack regimes: zone I is characterized by shallow short-duration snowpacks; zone II is charac-
terized by high interannual variability in snow depth and duration; zone III is characterized by early
developing, continuous snow cover; and zone IV is characterized by deep, long-duration snow
cover verging on perennial snowpacks. In zone I, soils remain frozen and there is little microbial
activity and N leachate is high. In zone II, total microbial activity is highly variable and the amount
of N leachate is highly variable. In zone III, total microbial activity is high and there is little N
leachate. In zone IV, microbial activity is reduced because of carbon limitation and N leachate is
high.
1
Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80302, USA
2
Department of Geography and Institute of Arctic and Alpine Research, University of Colorado, Boulder,
Colorado 80302, USA
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