Wednesday, June 6, 2007 - 8:30 AM
192

Determining the influence of wood on stream nitrate dynamics in forested headwater streams

Dana Richard Warren1, Kristin E. Judd, Ph.D.2, Darren L. Bade, Ph.D.2, Gene E. Likens, Ph.D.2, and Clifford E. Kraft, Ph.D.1. (1) Dept. of Natural Resources, Cornell University, Ithaca, NY 14853-3001, (2) Institute of Ecosystem Studies,, Milbrook, NY 12545

Nitrogen retention is an ecosystem function of interest in mitigating ecological impacts of anthropogenic nutrient loading.  Recent work indicates that forested headwater streams retain more nutrients than previously estimated and a number of correlative studies indicate that woody debris may be instrumental in nutrient retention.  We established an experimental study to specifically investigate the influence of woody debris on nitrogen dynamics in the Hubbard Brook Experimental Forest.  Pre-treatment data were collected on nitrate uptake in each of three replicate streams in 2005.  Estimates of nitrate flux into and out of each 100m reach were also conducted periodically in the first summer.  In fall 2005, wood was removed from one stream, was added to another, and was left unmanipulated in a third.  In summer and fall 2006 uptake and flux measurements were repeated.  A comparison of changes in nitrate dynamics before versus after wood manipulation (relative to the reference reach) indicates that wood addition had a strong influence.  Nitrate processing increased in response to wood addition but there was a more limited response to wood removal.  Wood addition to streams across northeastern North America will increase as forests continue to mature leading to potential increases in nitrate retention in these systems.


Web Page: www.people.cornell.edu/pages/drw23/research%20projects.html

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