Elevational Controls on Organic and Inorganic Nutrients in Stream Waters, Boulder Creek Watershed, Colorado Front Range

Jordan N. Parman and Mark W. Williams

Department of Geography and Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA

The panoramic splendor and complexity of mountain ecosystems have inspired and challenged humans for centuries. In our time, the perception that “mountains are forever” may provide solace to those seeking stability in a rapidly changing world. However, changes in the abundance and species composition of the native flora and fauna of mountain ecosystems are potential bellwethers of global change, because these systems have a propensity to amplify environmental changes within specific portions of this landscape. We examine the potential of mountain ecosystems to accumulate and redistribute exogenous materials from the atmosphere and endogenous materials from the mountains, as proposed in the Landscape Continuum Model (LCM, Seastedt et. al., 2004). Here we test the LCM by comparing and contrasting changes in organic and inorganic nutrients in stream waters of headwater catchments along an elevational gradient in the Colorado Front Range. We simultaneously collected water samples at four gauged headwater catchments: (1) Green Lakes Valley (3,500 m); (2) Como Creek (2,900 m); Gordon Gulch (2,400 m); and Betasso (1,830 m). All water samples were analyzed for DOC, DON, DOP, nitrate, and ammonium. Additionally, spectroscopic techniques were used to determine the quality of DOC. These measurements, along with supporting information on soil C:N ratios and climate data, will allow us to determine how elevational position controls: (a) the redistribution of exogenous materials from the regional environment such as nitrate in wetfall; and (b) endogenous sources originating from montane areas such as DOC and DON, while controlling for catchment size, aspect, and underlying geology.

Seastedt, T. R., W. D. Bowman, T. N. Caine, D. McKnight, A. Townsend & M. W. Williams (2004) The landscape continuum: A model for high-elevation ecosystems. Bioscience, 54, 111-121.