Elevational Controls On Organic And Inorganic Nutrients In Stream Waters From The Foothills To The Continental Divide, Boulder Creek CZO
Parman, Jordan N 1 ; Barnes, Rebecca T 2 ; Williams, Mark W 3 ; Hood, Eran W 4
1 Department of Geography and Institute of Arctic and Alpine Research, University of Colorado, Boulder
2 U.S. Geological Survey, Boulder, CO
3 Department of Geography and Institute of Arctic and Alpine Research, University of Colorado, Boulder
4 Department of Natural Sciences, University of Alaska Southeast, Juneau, Alaska
The Landscape Continuum Model (LCM) proposed a conceptual framework for how mountain ecosystems accumulate and redistribute exogenous material from the atmosphere and endogenous material derived from the mountain itself, emphasizing the importance of transport processes and redeposition of nutrients and water across highly various and complex terrain. 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); (3) Gordon Gulch (2,400 m); and Betasso (1,830 m) during the 2009 snowmelt season. All samples were analyzed for DOC, DON, nitrate, and ammonium. Additionally, spectroscopic techniques were used to determine the quality of DOM. These measurements, along with supporting information on soil C:N ratios and climate data, allowed us to determine the effect of elevation on biogeochemical cycling in headwater catchments, while controlling for catchment size, aspect, and underlying geology.
We found that while the LCM provides a useful conceptual framework for predicting nutrient concentrations in alpine catchments, lower elevation headwater catchments dominated by forest landcover demonstrate different biogeochemical cycling patterns. However,these broad-scale landcover type controls and elevational trends may also be confounded by temperature and precipitation patterns at the specific sampling sites.
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