HR: 14:00h
AN: NB23E-03    [Abstracts]
TI: The Influence of Leaf Fall and Organic Carbon Availability on Nitrogen Cycling in a Headwater Stream
AU: * Thomas, S A
EM: sat43@cornell.edu
AF: Department of Ecology and Evolutionary Biology,, Cornell University, Ithaca, NY 14853 United States
AU: Kristin, A
EM: ka29@cornell.edu
AF: Department of Natural Resources, Cornell University, Ithaca, NY 14853 United States
AU: Doyle, B
EM: rad26@cornell.edu
AF: Department of Natural Resources, Cornell University, Ithaca, NY 14853 United States
AU: Goodale, C L
EM: clg33@cornell.edu
AF: Department of Ecology and Evolutionary Biology,, Cornell University, Ithaca, NY 14853 United States
AU: Gurwick, N P
EM: npg1@cornell.edu
AF: Department of Natural Resources, Cornell University, Ithaca, NY 14853 United States
AU: Lepak, J
EM: jml78@cornell.edu
AF: Department of Natural Resources, Cornell University, Ithaca, NY 14853 United States
AU: Kulkari, M
EM: mvk5@cornell.edu
AF: Department of Natural Resources, Cornell University, Ithaca, NY 14853 United States
AU: McIntyre, P
EM: pbm3@cornell.edu
AF: Department of Ecology and Evolutionary Biology,, Cornell University, Ithaca, NY 14853 United States
AU: McCalley, C
EM: ckm27@cornell.edu
AF: Department of Ecology and Evolutionary Biology,, Cornell University, Ithaca, NY 14853 United States
AU: Raciti, S
EM: smr42@cornell.edu
AF: Department of Natural Resources, Cornell University, Ithaca, NY 14853 United States
AU: Simkin, S
EM: sms242@cornell.edu
AF: Department of Natural Resources, Cornell University, Ithaca, NY 14853 United States
AU: Warren, D
EM: drw23@cornell.edu
AF: Department of Natural Resources, Cornell University, Ithaca, NY 14853 United States
AU: Weiss, M
EM: msw27@cornell.edu
AF: Department of Ecology and Evolutionary Biology,, Cornell University, Ithaca, NY 14853 United States
AB: The study of allochthonous carbon has a long and distinguished history in stream ecology. Despite this legacy, relatively little is known regarding the influence of leaf litter on nutrient dynamics. We conducted ¹⁵N-NO₃ tracer additions to a headwater stream in upstate New York before and after autumn leaf fall to assess the influence of leaf litter on nitrogen spiraling. In addition, we amended the stream with labile dissolved organic carbon (as acetate) midway through each experiment to examine whether organic carbon availability differentially stimulated nitrogen cycling. Leaf standing stocks increased from 53 to 175 g dry mass m^-2 and discharge more than tripled (6 to 20 L s^-1) between the pre- and post-leaf fall period. In contrast, nitrate concentration fell from approximately 50 to less then 10 ug L^-1. Despite higher discharge, uptake length was shorter following leaf fall under both ambient (250 and 72 m, respectively) and DOC amended (125 and 45 m) conditions. Uptake velocity increased dramatically following leaf fall, despite a slight decline in the areal uptake rate. Dissolved N₂ gas samples were also collected to estimate denitrification rates under each experimental condition. The temporal extent of increased nitrogen retention will also be explored.
DE: 0400 Biogeosciences
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly