HR: 08:15h
AN: GC31C-02 INVITED    [Abstracts]
TI: Complex Patterns in Climate and Atmospheric Nitrogen Deposition Influence Rocky Mountain Ecosystems
AU: * Baron, J S
EM: jill@nrel.colostate.edu
AF: U.S. Geological Survey, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523-1499, United States
AU: Schmidt, T
EM: tschmidt@lamar.colostate.edu
AF: U.S. Geological Survey, Fisheries and Wildlife Department, Colorado State University, Fort Collins, CO 80523, United States
AU: Hartman, M D
EM: melannie@nrel.colostate.edu
AF: Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523- 1499, United States
AU: Enders, S K
EM: sara.enders@yale.edu
AF: Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109, United States
AU: Pagani, M
EM: mark.pagani@yale.edu
AF: Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109, United States
AU: Wolfe, A P
EM: awolfe@ualberta.ca
AF: Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada
AU: Krcmarik, A
EM: krcmarik@hotmail.com
AF: Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523- 1499, United States
AB: Long-term monitoring of physical and biogeochemical characteristics in Loch Vale watershed, Rocky Mountain National Park, has revealed complicated patterns in temperature, precipitation, and atmospheric nitrogen deposition. July mean and maximum temperatures have increased since 1985 by 0.1-0.2 ° C, while March mean and maximum temperatures became 0.1-0.3 ° C colder. There is no long-term trend in annual or monthly precipitation; annual totals range 75-140 cm yr^-1. Atmospheric N deposition has increased approximately 2% yr^-1 since 1985, and there are strong upward trends in July and September deposition. A combination of observations, ecosystem modeling (DayCent-Chem model), and structural equation modeling (SEM) suggests this alpine/subalpine catchment is responding physically, biologically, and chemically. Observed stream discharge was greater than measured precipitation in several recent years, indicating melt from glacier ice contributes to flow. Model results suggest a strong increase in alpine microbial activity and plant N uptake, and a moderate increase in forest microbial activity driven by increased temperatures and increased N deposition. Alpine lichen activity appears to also have been significantly stimulated. There has been a significant increase in observed stream nitrogen concentrations and flux. Annual mean stream N concentrations in alpine/subalpine Loch Vale watershed of Rocky Mountain National Park have increased from approximately 1.0 to 1.5 mg NO₃ L^-1 between 1991 and 2005; the annual amplitude has also increased. Mean annual N efflux from the catchment doubled between 1991 and 2005. SEM suggests N loss from Loch Vale appears to result most strongly from the combined influence of temperature and precipitation on stream flow, and secondarily from the influence of terrestrial nitrogen cycling.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1813 Eco-hydrology
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting