Document: TOC-3-99-151

Mechanisms regulating C and N transformations, Olympic National Park.

TOCZYDLOWSKI, D.* 1 and R.STOTTLEMYER 2

Michigan Technological University, Houghton, MI 49931 USA 1
U. S. Geological Survey, Ft. Collins, CO 80526 USA 2

Abstract:
The objective of this ongoing 3-yr study, across a precipitation gradient of 50 to 320 cm yr-1, is to see how forest plot-level processes might help explain watershed outputs of major ions, dissolved organic carbon (DOC), and dissolved organic nitrogen (DON). Stream discharge is dominated by snowmelt in the drier sites with less seasonal change in discharge at the wettest site. The snowpack contains >50% of annual precipitation and ion input. Forest O2 C and N content increase with moisture, but the C:N ratios peak (36) at the dry end of the precipitation gradient. In the snowmelt-dominated watershed, stream water discharge is inversely correlated (p <0.05) with base cation (CB), SO42-, Si concentrations, and positively correlated with DOC concentration. This pattern indicates a steady seasonal change in soil water flowpath and the importance on chemical export of both deep and shallow seasonal subsurface flow. This relationship did not exist at the drier or wetter ends of the precipitation gradient. Despite the precipitation gradient, all watersheds strongly retained inorganic N inputs.

Keywords: watershed

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This abstract is being presented at: 3:30 PM in session:
Poster Session #15: Nutrient Cycling.