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Nutrient Concentration Patterns in a Stream Draining a Montane Ecosystem in Utah

Bond, Hedley W.
Ecology 1979 v.60 no.6 pp. 1184-1196
calcium carbonate, ecosystems, groundwater flow, ions, loci, nutrient content, nutrients, overland flow, stream flow, streams, subsurface flow, watersheds, Utah
The concentrations of several nutrients in a stream draining a large montane ecosystem in northern Utah, USA were monitored over a 2—yr period. Stream discharge (cubic metres per day) accounts for much of the variation in the concentration of the most common nutrients. When the concentration of each nutrient is plotted logarithmically against stream discharge and the points are joined in a time sequence, a locus or trajectory is obtained which varies more between ions than between years for the same ion. These patterns of nutrient flux appear to be controlled largely by the magnitude of stream discharge and the relative contributions of groundwater flow, overland flow, and interflow. Plant uptake, supply of exchangeable ions, and equilibrial dynamics of the calcium carbonate system also influence the shape of the trajectories and give rise to much of the differences between trajectories for different ions. The trajectories for less common ions are more variables than those for abundant entities. Available data indicate that trajectories are observed in other ecosystems but are only seen clearly in watersheds with a simple annual pattern of streamflow. These patterns of nutrient flux occur for each significant rise and fall in stream discharge and are not observed distinctly in ecosystems with frequent changes in streamflow. The characteristic and recurring form of trajectories suggests that these patterns represent an important and general property of some ecosystem and that they may provide a basis for a theoretical approach to ecosystem nutrient dynamics.